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***********************************
* *
* COURIER V.34 Manual *
* *
***********************************
Copyright 1994 by U.S. Robotics, Inc.
U.S. Robotics, the U.S. Robotics logo, and HST are registered trademarks
of U.S. Robotics, Inc. Courier HST Dual Standard Fax, Courier V.32 terbo
Fax, Total Control, and Adaptive Speed Leveling (ASL) are trademarks of
U.S. Robotics, Inc. V.Fast Class and V.FC are trademarks of Rockwell
International. Any trademarks, tradenames, service marks or service names
owned or registered by any other company and used in this manual are the
property of their respective companies.
*****************************************************************************
TABLE OF CONTENTS
*****************************************************************************
How to Use this Manual
Table of Contents
Limited Warranty
FCC Registration Numbers
IC (Industry Canada)
Connecting to the Telephone Company
Radio and Television Interference
For Canadian Modem Users
PART I. INSTALLATION AND OPERATION
Chapter 1--Features and Compatibility
Introduction
Features
Compatibility
Fax Standards
Other Compatibility Features
Chapter 2--External Modem Set Up
Switches on the Modem
Front Panel Indicators on the Modem
Package Components
What You Need
An RS-232 Cable
Communications Software. . .
Telephone Adapter. . .
You Should. . .
Refer to Appendix F. . .
Refer to Appendix G. . .
Installing the Modem
Testing the Installation
Chapter 3--Internal Modem Set Up
Package Components
What You Need
Communications Software. . .
A Telephone Adapter
You Should. . .
Refer to Appendix F. . .
Refer to Appendix G. . .
Before Installing the Modem
Select a Serial Port
Select an Interrupt Request (IRQ)
Reset the Jumpers
Set DIP Switches
Installing the Modem
Testing the Installation
Chapter 4--Data Mode Command Summary
Command Set Usage
Basic Commands
Dialing/Answering
Dialing
Dial Options
Cancel Dialing
Store Phone Numbers
Redialing
Answer Mode
Hanging Up
Setting/Using Defaults
Customizing NVRAM
Resetting the Modem
Configuration
Echo/Speaker
Result Codes
Additional Result Code Sets
Modulation
Error Control/Data Compression
Data Rates
RS-232 Signal Operations
Flow Control
S-Registers
Inquiry and Help
Testing
International Calls
Miscellaneous Commands
Chapter 5--Fax Operations and Call Detection
Fax Operations
Notes to Programmers
Call Detection
Chapter 6--Queries and Help Screens
User Inquiries
S-Register Query
Phone Number Query
Last-Dialed Number Inquiry
Stored Command String Query
Help Screens
Stop/Restart Display
Cancel Display
Basic Command Set
Extended Command Set
Dialing
S-Register Functions
Percent Commands
PART II. REFERENCE
Appendix A--Link Negotiation (Handshaking) and Error Control
V.34 Handshaking
V.Fast Class (V.FC) Handshaking
U.S. Robotics V.32 terbo to U.S. Robotics V.32 terbo
Other V. Protocol Operations
Dual Standard Handshaking
Error Control and Throughput
V.42 Handshaking
MNP Handshaking
Data Compression
Flow Control
Throughput Guidelines
Typical Throughput
Appendix B--Summaries and Tables
The RS-232 Interface
Front Panel Indicators
DIP Switch Summary
Default Settings
Factory Templates
&F1 Hardware Flow Control (Default)
&F2 Software Flow Control
&F3 HST Cellular
&F0 No Flow Control
NVRAM Options
S-Register Summary
ASCII Chart
Appendix C--Alphabetical Command Summary
Command Set Usage
Basic Command Set
Ampersand (&) Command Set
Percent (%) Command Sets
Appendix D--Dial Security/Remote Access
Dial Security
Remote Access
Appendix E--Troubleshooting
Appendix F--Synchronous and Leased Line Operations
Synchronous
V.25 bis
Online synchronous
Dedicated Line and Leased Line Operations
Appendix G--Additional Operations
Cellular Operations
Voice/Data (External Modems Only)
Hewlett Packard 3000 Installations
MI/MIC Operations (External Modems Only)
Appendix H--Modem Testing
Testing with &T
Ending a Test--&T0, S18
Analog Loopback--&T1, &T8
&T2
Digital Loopback--&T3
&T4, &T5
Remote Digital Loopback--&T6, &T7
Testing with Register S16
Analog Loopback--S16=1D
Dial Test--S16=2
Test Pattern--S16=4
Remote Digital Loopback--S16=8
Appendix I--Software Upgrades
Appendix J--Glossary
Appendix K--Technical Specifications
Index
**********************
HOW TO USE THIS MANUAL
This manual contains operating instructions for Courier Dual Standard
V.34 and Courier V.34 modems. These modems have many similar features
except for the signaling they use to connect with remote modems at high
speeds: V.32/V.32 terbo, HST, V.FC, or V.34. Courier HST Dual Standard
modems use any type of signaling, depending on the type of remote modem.
V.34 modems can connect at rates up to 28.8K bps.
Below is a brief description of the manual's contents.
* Chapter 1--Operating and Compatibility Features
* Chapter 2--Installation
* Chapter 3--Internal Modem Installation
* Chapter 4--Data Mode Commands
* Chapter 5--Fax Mode and Call Selection
* Chapter 6--Queries and Help commands to display current settings,
operational summaries, and other data
* Background information on protocols, error control, and throughput
* Summaries and tables
* Alphabetical Command Summary
* Dial Security operations
* Troubleshooting
* Online synchronous and V.25 bis synchronous operations
* Additional features such as HST Cellular and voice/data switch
* Procedures for modem testing
* Procedures for upgrading your modem via software downloads
* Glossary
* Warranty/Service/Certification information
*********************************
A Note on Communications Software
If you're using a computer rather than a terminal, you need communications
software. Many brands are available, all of which are based on the modem's
AT command set. Some users prefer their communications software to take
control of the modem, and are more comfortable with a program that makes
the modem almost transparent. Others prefer a program that allows them to
use the modem's AT command set sometimes, and their software at other times,
depending on the task at hand. Review at least Chapter 4 so that you have a
basic understanding of the modem's requirements and operation.
****************
LIMITED WARRANTY
U.S. Robotics, Inc., warrants to the original consumer or other end user
purchaser that this product is free from defects in materials or workmanship
for a period of two years from the date of purchase. During the warranty
period, and upon proof of purchase, the product will be repaired or replaced
(with the same or similar model) at our option, without charge for either
parts or labor. This warranty shall not apply if the product is modified,
tampered with, misused, or subjected to abnormal working conditions.
REPAIR OR REPLACEMENT AS PROVIDED UNDER THIS WARRANTY IS THE EXCLUSIVE
REMEDY OF THE PURCHASER. THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES,
EXPRESS OR IMPLIED, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR USE OR PURPOSE, AND U.S. ROBOTICS SHALL IN NO EVENT
BE LIABLE TO PURCHASER FOR INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND OR
CHARACTER.
Some states do not allow the exclusion or limitation of incidental or
consequential damages or allow limitations on how long an implied warranty
lasts, so the above limitations or exclusion may not apply to you. This
warranty gives you specific legal rights. You may also have other rights
which vary from state to state.
Should you encounter problems in operating this device, follow the
instructions in Appendix E in Part II of this manual. The appendix contains
solutions to operating problems as well as procedures to follow if there is
an apparent modem malfunction.
****************
FCC REGISTRATION
FCC68: CJEUSA-73130-FA-E
RINGER EQUIVALENCE: 0.4B
FCC15:
CJE-0263 (External modem)
CJE-0269 (Internal modem)
CJE-158-243 (Motherboard)
CJE-0151-243 (Daughterboard)
********************
IC (Industry Canada)
This digital apparatus does not exceed the Class B limits for radio noise
emissions from digital apparatus set out in the radio interference
regulations of Industry Canada (formerly Canadian Department of
Communications).
Le present appareil numerique n'emet pas de bruits radio-electriques
depassant les limites applicables aux appareils numeriques de la classe
B prescrites dans le Reglement sur le brouillage radioelectrique edicte
par le ministere des Communications du Canada.
***********************************
Connecting to the Telephone Company
It is not necessary to notify the telephone company before installing
the modem. However, the telephone company may request the telephone
number(s) to which the Courier is connected and the FCC information
printed above.
If the modem is malfunctioning, it may affect the telephone lines. In this
case, disconnect the modem until the source of the difficulty is traced.
Do not use the modem on party or coin telephone lines.
*********************************
Radio and Television Interference
This equipment generates and uses radio frequency energy, and, if not
installed and used properly in strict accordance with the manufacturer's
instructions, may cause interference to radio and television reception.
Courier high speed modems have been tested and found to comply with the
limits for a Class B computing device in accordance with the specifications
in Part 15 of FCC rules, which are designed to provide reasonable protection
against such interference in a residential installation.
However, there is no guarantee that interference will not occur in a
particular installation. If this device does cause interference to radio
or television reception, which you can determine by monitoring reception
when the modem is on and off, try to correct the problem with one or more
of the following measures.
* Reorient the receiving antenna.
* Relocate the computer with respect to the receiver.
* Relocate the computer and/or the receiver so that they are on separate
branch circuits.
If necessary, consult your dealer or an experienced radio/ television
technician for additional suggestions. You may find the following booklet,
prepared by the Federal Communications Commission, helpful:
How to Identify and Resolve Radio-TV Interference Problems
Stock No. 004-000-0345-4
U.S. Government Printing Office
Washington, DC 20402
In accordance with Part 15 of the FCC rules, any modification to or
tampering with this device that causes harmful interference to others may
be reason for prohibiting future operation.
************************
For Canadian Modem Users
The Industry Canada (formerly DOC) label identifies certified equipment.
This certification means that the equipment meets certain telecommunications
network protective, operational, and safety requirements. The department
does not guarantee the equipment will operate to a user's satisfaction.
Before installing this equipment, make sure you are permitted to connect it
to the facilities of the local telecommunications company. You must also
install the equipment using an acceptable method of connection. In some
cases, you may also extend the company's inside wiring for single line
individual service by means of a certified connector assembly (telephone
extension cord). You should be aware, however, that compliance with the
above conditions may not prevent degradation of service in some situations.
Repairs to certified equipment should be made by an authorized Canadian
maintenance facility designated by the supplier. Any repairs or alterations
made by a user to this equipment, or equipment malfunctions, may give the
telecommunications company cause to request the user to disconnect the
equipment.
For your own protection, make sure that the electrical ground connections
of the power utility, telephone lines, and internal metallic water pipe
system, if present, are connected together. This precaution may be
particularly important in rural areas.
WARNING: Do not attempt to make such connections yourself; contact the
appropriate electric inspection authority or electrician.
Courier High Speed Modems Load Number: 5
The Load Number (LN) assigned to each terminal device denotes the
percentage of the total load to be connected to the telephone loop used
by the device, without overloading. The termination on a loop may consist
of any combination of devices, subject only to the requirement that the
total of the Load Numbers of all the devices not exceed 100.
Chapter One--Features and Compatibility
************
INTRODUCTION
Congratulations! The Courier modem you've purchased represents powerful,
advanced electronic design that offers exceptional reliability,
compatibility and flexibility at all standard rates up to 28,800 or
28.8K bits per second (bps). The transmission rate between the computer
and modem, depending on your equipment and software support, can be as
high as 115.2K bps.
********
Features
The following features and capabilities assure you of superior reliability
and performance.
Connections up to 28.8K bps
With the V.34 standard and the V.Fast Class modulation scheme, two modems
can connect at rates up to 28.8K bps, twice as fast as the rates of standard
ITU-T (formerly CCITT) V.32 bis modems, which are limited to calls of 14.4K
bps or less.
Software Upgrades
Courier high speed modems are now software upgradable, allowing you quick,
easy access to the latest advances in data communication technology. See
Appendix I.
Quick Connect
In V.32 terbo mode, Courier high speed modems can handshake and start
transmitting much faster than typical training times that range between
9 and 18 seconds for other modems.
Universal Connect
Courier high speed modems automatically detect and connect at the fastest
available speed.
Adaptive Speed Leveling (ASL)
Like most high speed modems, Courier modems fall back to the next lower
speed<EFBFBD>for example, 19.2K, then 16.8K in V.terbo mode--if poor line conditions
warrant. In addition, Courier V.32 bis, and V.32 terbo modems detect
improved line conditions and shift upward again to the next higher speed.
Both transmit and receive channels adapt independently, each detecting and
adjusting to line conditions. ASL keeps the modems online, always operating
at the highest possible speed, and constantly ensuring data integrity.
Fax Capability
You can use your modem with Class 1 or Class 2.0 facsimile software to
exchange faxes with millions of Group III fax machines worldwide. See
Chapter 5.
Error Control--V.42/MNP
Data integrity is ensured when the modems connect with remote modems that
use the V.42 (LAPM), HST, or MNP error control protocols. Error control is
available on calls at 1200 bps and above.
Data Compression--V.42 bis/MNP5
Data compression enables potential throughput of up to 115.2K bps on 28.8K
bps connections. Couriers connecting under V.42 or HST error control use
V.42 bis compression. Couriers connecting under MNP error control use
MNP Level 5 compression. Typical throughput of text and other types of
files using V.42 bis is provided in Appendix A.
Flow Control/Variable Serial Port Rates
Flow control, required under error control, also allows the local serial
port (DTE) rate to be set higher than the link (connection) rate, enabling
greater efficiency and throughput. If your equipment and software support
high rates, data can be sent from the computer to the modem at 115.2K,
57.6K, 38.4K or 19.2K bps, regardless of the link rate.
Voice/Data Switch
A switch on the modem's front panel allows you to change from voice to data
and back again, without issuing a command. See Appendix G.
Stored Command String
If you don't ordinarily use voice and data in the same call, you can assign
the voice/data switch a different function that normally requires a command,
such as resetting the modem or executing a stored command string. See
Voice/Data in Appendix G for instructions on use of the voice/data switch.
Asynchronous/Synchronous Capability
Courier high speed modems operate synchronously as well as asynchronously.
A personal computer equipped with a synchronous interface adapter can call
computers that use standard synchronous protocols. See Appendix F for more
information.
Synchronous Operations with V.25 bis
Used with computers that have a synchronous card and port, Courier high speed
modems combine the power of older modems and automatic calling units in the
mainframe environment. They make synchronous connections by utilizing V.25
bis, character-oriented (similar to BISYNC) and HDLC protocols. See
Appendix F for more information.
Dial Security
With Dial Security, you will be able to prevent unauthorized access to a
system with the use of Autopass, Prompting, and Dialback. See Appendix D
for more information.
Programmable Nonvolatile Memory
You can tailor your own default settings and store them in nonvolatile
random access memory (NVRAM). Each time the Courier is powered on or reset,
it operates at the settings you've specified. See Chapter 4, Appendix B,
and Appendix C.
Link Rate Negotiation
The Courier automatically lowers its link rate to match a lower rate of a
remote modem, in both Originate and Answer Modes, allowing connections with
a wide range of installed modems.
Link Diagnostics
After each call, you can display a Link Diagnostics screen containing
information about the last call, including the number of data characters
transferred, line statistics, the call's rate and the reason the call was
disconnected. See Chapter 6.
Modem Diagnostics
ITU-T V.54 loopback testing with the &T command options, and earlier Courier
Register S16 test options are available. The modem performs three loopback
tests: analog, digital, and remote digital. See Appendix H for information.
Inactivity Timer
You can set the modem to automatically hang up after a specified number of
minutes if there is no activity on the phone line. See Register S19 in
Appendix B.
Call Duration Reporting
The modem records the duration of your calls in hours, minutes, and seconds.
This feature enables you to display and print an audit of your calling
activities. You can optionally use the modem clock as a real-time clock.
See the I3 and I6 screens in Chapter 6 and the K command in Chapter 4 and
Appendix C.
Call Progress Detection
An optional set of result codes (screen messages) lets you know when a
line is busy, a person rather than a modem has answered the phone, there
is no dial tone, or the distant phone is ringing.
Modem Settings Displays
On command, the modem displays its current settings, a handy way to check
your transmission rate, S-Registers and other operational controls. The
modem also displays the defaults stored in nonvolatile memory as well as
its default configuration templates. See Chapter 6.
HELP Screens
The modem displays screens that summarize the command sets, Dial command
options, and S-Register functions. See Chapter 6.
Bottom Panel Reference
Command summaries and other information are printed on the bottom of the
modem case. A Dual In-Line Package (DIP) switch guide makes it easy to
tailor the switch settings to your terminal or software requirements.
Dialing the Last-Dialed Number
The modem has a buffer that stores each dialed number until it is cleared
by another Dial command. A few keystrokes cause the modem to redial the
number in the buffer without your having to enter the number again. See
the DL command in Appendix C.
Automated Redialing
You can put the modem into Repeat Mode to continuously redial if a previous
dial attempt fails to connect. This is especially useful in dialing
services whose lines are often busy. See Chapter 4.
Quote Mode
Set the modem to Quote Mode if you want it to dial an alphabetic acronym
instead of a numeric number. See Chapter 4.
*************
COMPATIBILITY
The Courier adheres to the following modulation schemes and standards,
ensuring compatibility with a wide base of installed modems. Unless
otherwise indicated, Dual Standard V.34 modems conform to the listed
standards.
NOTE: The International Telecommunication Union (ITU-T) was formerly the
International Telegraph and Telephone Consultative Committee (CCITT).
ITU-T V.34 28.8K/26.4K/24K/21.6K/19.2K/16.8K/14.4K/12K/
9600/7200/4800/2400 bps
V.FC 28.8K/26.4K/24K/21.6K/19.2K/16.8K/14.4K bps
V.32 terbo 21.6K/19.2K/16.8K/14.4K/12K/9600/
7200/4800 bps
HST 16.8K/14.4K/12K/9600/7200/4800 bps (Dual Standard modems
in HST mode with ASL up to 21.6K bps)
HST Cellular Cellular connections at 12K/9600/7200/ 4800/2400/1200/300 bps
(Dual Standard modems in HST mode)
ITU-T V.32 bis 14.4K/12K/9600/7200/4800 bps
ITU-T V.32 9600/4800 bps
ITU-T V.22 bis 2400 bps
Bell 212A 1200 bps (also V.22)
ITU-T V.23 1200 bps with 75 bps back channel (some U.K. and European
phone systems)
ITU-T V.25 Answer sequence for calls originating outside the U.S. and
Canada
ITU-T V.25 bis For synchronous communications using HDLC and character-
oriented protocols
Bell 103 300 bps (ITU-T V.21 optional)
ITU-T V.42 LAPM error control, 1200 bps and higher
ITU-T V.42 bis Data compression, 1200 bps and higher
MNP Levels 2, 3 and 4 error control, level 5 data compression,
1200 bps and higher
ITU-T V.54 Analog, digital and remote digital loopback testing
*************
Fax Standards
The Courier modem provides Group III-compatibility when combined with Class
1 or Class 2.0 fax software. In addition, the modem adheres to the following
standards.
TIA/EIA-578 Service Class 1 Asynchronous Facsimile DCE Control Standard
TIA/EIA-592 Service Class 2.0 Asynchronous Facsimile DCE Control Standard
ITU-T V.17 14.4K/12K bps
ITU-T V.29 9600/7200 bps
ITU-T V.27 ter 4800/2400 bps
ITU-T V.21 300 bps
****************************
Other Compatibility Features
Other compatibility features include the following standards and
certification:
* Can be used with any computer or terminal that is compatible with the
RS-232 standard interface.
* Can be used with any computer or terminal that uses ASCII, the standard
character code supported by most equipment manufacturers.
* Is fully FCC- and IC-certified for the uses described in this manual.
Chapter 2--Modem Set Up
********
Reminder
To prevent overheating, do not cover the vents on the top of the modem case.
*********************
Switches on the Modem
Voice/Data
This push-button switch is used primarily to switch between voice and data
communications during a call. Detailed instructions are in the Voice/Data
Calls section in Appendix G.
Volume Control
This is a slide switch underneath the right side panel of the modem, near
the front corner. Sliding it toward the front of the modem increases the
modem speaker's volume; sliding it toward the rear of the modem decreases
the volume.
Front Panel Indicators on the Modem
The modem has twelve status lights, or LEDs. See Appendix B for descriptions
of their operations.
PACKAGE components
Your Courier modem package contains the following items:
* The modem you purchased: Courier V.34
* An RJ11C phone cord
* A power adapter
* Fax software and manual
* A Quick-Reference card
*************
What You Need
The Courier modem has minimal operational requirements. Be sure to read the
information in the front of this manual about radio and television
interference and connecting to the phone company. In addition, you should
be aware of the following requirements.
An RS-232 Cable
You need an RS-232 cable to connect the modem to your computer or terminal.
Use a shielded cable to ensure minimal interference with radio and
television reception.
NOTES:
* Refer to Appendix B for a listing of RS-232 pin assignments required to
operate the modem. Be sure to check the appendix if you're not sure what
type of cable you need, or if you're building your own.
* If your machine has other than a 25- or 9-pin port, check your computer
documentation or consult your dealer to find out what type of RS-232
connector is required.
WARNING: If you're planning to use the high speed computer-to-modem rates
of 115.K, 57.6K or 38.4K bps, follow the instructions concerning the RS-232
cable in Appendix B. The guidelines there will help you to avoid signal
degradation at very high speeds.
Communications Software. . .
. . .if the modem is attached to a computer instead of a terminal.
The software uses the modem's AT command set to control many communications
functions, including configuring the modem, dialing, and answering calls, and
also enables the transfer of files and other operations.
Some users prefer their communications software to take control of the
modem, and are more comfortable with a program that makes the modem almost
transparent. Others prefer a program that allows them to use the modem's
AT command set sometimes, and their software at other times, depending on
the task at hand.
Review Chapter 4 so that you have a basic understanding of the modem's
requirements and operation.
Telephone Adapter. . .
. . .if you have an older telephone installation that does not have the
appropriate modular wall jack and plug.
Adapters and RJ11C connectors are available from your telephone company or
computer dealer.
***************
You Should. . .
Refer to Appendix F. . .
. . .if your phone line is user-installed or if it is leased from the
telephone company.
Refer to Appendix G. . .
. . . if your modem is installed in a Hewlett Packard system that uses the
Ack/Enq communications protocol.
********************
Installing the Modem
1. Turn off the computer or terminal and its peripheral devices.
2. Examine the label on the bottom of the modem. In addition to the
summaries and other information, the label contains icons to aid in
modem installation.
3. Make sure that the modem's power switch is OFF; press it towards the zero
in the 0/1 icon on the bottom label.
4. Plug the power supply adapter's small connector into the power jack at
the back of the modem. Plug the adapter into a standard 115-volt AC
wall socket.
5. Disconnect your present phone cable from the wall jack. Plug one end of
the supplied phone cable into the modem's phone jack (refer to the bottom
label). Plug the other end into the wall jack.
If you want to keep your telephone connected for conventional calls, plug
its cord into the modem's telephone jack (refer to the bottom label).
6. Check the positions of the bank of Dual In-Line Package (DIP) Switches
located in the well at the bottom of the modem. These switches are set
at the factory to the positions most users require.
Check your software documentation for its requirements, particularly for
DIP switches 1, 4, 5 and 6. You'll also find descriptions of switch
functions and options in Appendix B.
NOTE: If you have built your own RS-232 cable and it does not support the
Data Terminal Ready (DTR) signal, set DIP switch 1 ON, for DTR override.
The override causes the modem to operate as if the DTR signal were always
ON, and enables the modem to accept commands. Most purchased communications
software, however, requires normal DTR.
7. The final step is to connect the modem to the computer's or terminal's
serial port with the RS-232 cable. Attach the appropriate connectors to
the modem and to the serial port.
************************
Testing the Installation
Use the following procedures to verify that your modem is working properly.
1. Turn on your computer or terminal. Then turn the Courier's power switch
ON. The following front panel indicators, or LEDs, will light up on the
modem.
CD Carrier Detect, if you have set DIP switch 6 ON, enabling the
CD override
TR Data Terminal Ready, if you have set DIP switch 1 ON, enabling
the DTR override
MR Modem Ready/Power ON
CS Clear to Send
2. If you're using a personal computer, load your software to start the
program. Set your terminal or software to 19.2K bps or 9600 bps.
In addition, set a word length of either 7 bits plus 1 parity bit, or
8 bits with no parity<74>it doesn't matter which at this time<6D>and 1 Stop bit.
Set the software to use the correct serial port (port through which the
modem connects to the computer).
3. Perform the function that lets you send AT commands to the modem, that is,
puts the computer in Terminal mode. Some communications programs do
this automatically upon loading. Others require you to display a
communications or terminal screen, type a Function key, or perform some
other operation.
Review your communications software documentation for instructions.
4. Send the following attention command. Type either upper or lower case
letters, not a combination, and then press the Enter (Carriage Return)
key, shown in the example below between angle brackets. (Don't type the
angle brackets.)
AT <Enter>
If everything is correct, the modem responds as follows:
OK
Go on to step 5.
Troubleshooting
If your entered command is not displayed, your local echo is OFF. To
turn the local echo ON, send the modem the following command:
ATE1 <Enter>
If double characters appear on the screen, both your modem and software
are set to local echo ON. Either set your software to local echo OFF,
or turn the modem's echo OFF with the following command:
ATE0 <Enter>
If no OK appears on your screen after you completed Step 4, review the
following checkpoints:
a. Make sure you type all upper or lower case letters and press <Enter>.
b. Check to see that you set your communications software to the correct
serial port. The correct serial port is the port through which the
modem is connected to the computer.
c. Make sure your software has put the computer in Terminal mode, so that
you can send the modem commands. Then review Step 4, on the previous
page.
d. Be sure that DIP switches 1 and 6 are set ON or OFF according to your
terminal or software requirements. The table in Appendix B explains
each function, and you may also need to review your terminal or
communications software documentation.
e. If you set DIP switch 8 OFF, for Dumb mode, reset the modem to Smart
mode: set DIP switch 8 to ON.
f. The modem is shipped with DIP switch 3 ON, enabling the result codes.
If DIP switch 3 is OFF, set it to the ON position. Then initiate the
new switch setting with the following reset command:
ATZ <Enter>
5. As a final check, make sure the modem gets a dial tone. Type the
following Dial command:
ATD <Enter>
On receipt of the command, the modem goes off hook and waits for a dial
tone. The OH indicator lights up, and you'll hear the dial tone from
the modem's speaker. To cancel the operation, press any key.
Troubleshooting
If you don't hear the dial tone, first increase the volume by sliding the
volume control switch towards the front of the modem. If that doesn't
work, check to see that the phone cable from the wall jack is connected to
the correct jack on the modem (See Figure 2.3). If necessary, reconnect
the phone cable correctly. Then try the Dial command again, ATD <Enter>.
Chapter Three--Internal Modem Set Up
******************
Package Components
Your Courier modem package contains the following items:
* The modem you purchased: Courier V.34
* An RJ11C phone cord
* A power adapter
* Fax software and manual
* A Quick-Reference card
************
What You Need
The Courier modem has minimal operational requirements. Be sure to read
the information in the front of this manual about radio and television
interference and connecting to the phone company. In addition, you should
be aware of the following requirements.
Communications Software. . .
. . .if the modem is attached to a computer instead of a terminal.
The software uses the modem's AT command set to control many communications
functions, including configuring the modem, dialing, and answering calls,
and also enables the transfer of files and other operations.
Some users prefer their communications software to take control of the
modem, and are more comfortable with a program that makes the modem almost
transparent. Others prefer a program that allows them to use the modem's
AT command set sometimes, and their software at other times, depending on
the task at hand.
Review Chapter 4 so that you have a basic understanding of the modem's
requirements and operation.
A Telephone Adapter. . .
. . .if you have an older telephone installation that does not have the
appropriate modular wall jack and plug.
Adapters and RJ11C connectors are available from your telephone company or
computer dealer.
***************
You Should. . .
Refer to Appendix F. . .
. . .if your phone line is user-installed or if it is leased from the
telephone company.
Refer to Appendix G. . .
. . . if your modem is installed in a Hewlett Packard system that uses the
Ack/Enq communications protocol.
***************************
BEFORE INSTALLING THE MODEM
A typical new modem user has a PC with a printer connected to the PC's
parallel printer port, and a mouse cable attached to the PC's first
serial port. For this user, the modem is the only device that requires
a second serial port. If this is your situation, you can skip this
entire section except for DIP Switches, just before Installing the Modem.
Just remember that after you load your communications software, you'll
have to set the software to use the COM2 serial port.
IBM PC-compatible serial ports are referred to as COM ports. Two COM ports
are standard: COM1 and COM2. DOS recognizes up to four COM ports, although
more can be programmed. The Courier is set at the factory to use COM2.
This is because many computers are shipped with COM1 equipped with an
external serial connector for attaching a device such as a serial printer
or serial mouse. If you have one or more of these devices, you're probably
already familiar with COM ports on a PC.
If you're only using COM1 for a device, you can skip this section except
for DIP Switches, just before Installing the Modem. If you've already
installed devices at both COM1 and COM2, you will have to select either
COM3 or COM4. Carefully review the following section for complete
instructions.
********************
Select a Serial Port
WARNING: If you are going to use COM1, COM3, or COM4, you must change some
switches on the modem board, called jumpers. First, you need to select the
correct Interrupt Request (IRQ) to use at that serial port. Peripheral
devices use IRQs to instruct the computer to stop the processor's current
operation; this allows the devices to perform their operations.
Using COM1, 2, 3 or 4 depends on your equipment's configuration, as
described below. Remember which serial port you assign to the modem,
because you must specify it to your
communications software later.
The table in the next section includes hexadecimal addresses, required
by some software.
COM1: You may use this port if the computer does not have an installed
serial connector at COM1. (This situation is unlikely.) You
will have to modify some switches on the modem, so be sure to
read this entire section of the chapter. However, you may prefer
to leave the modem set to COM2 and proceed to DIP Switches, just
before the installation instructions.
COM2: If your computer is equipped with one serial connector at COM1,
and if you are not already using COM2 for another device, use
this port. (This is the most common configuration.) Since the
modem is already set to operate at COM2, skip the rest of this
section and proceed to DIP Switches, just before the installation
instructions.
COM3, COM4: If you have two serial devices that already use COM1 and COM2,
you can set the modem for either COM3 or COM4. Review your
communications software documentation to be sure your program
supports these additional serial ports. (Most programs do.)
If your software doesn't, you will have to remove one of the
other devices.
*********************************
Select an Interrupt Request (IRQ)
IBM-compatible computers reserve IRQ4 for COM1 and IRQ3 for COM2, as shown
below. Some communication programs support reserved IRQs for two serial
ports.
Serial Port IRQ Serial Port Address (Hex)
COM1 IRQ4 3F8-3FF
COM2 IRQ3 2F8-2FF
COM3 IRQ4* 3E8-3EF
COM4 IRQ3* 2E8-2EF
*Select IRQ4 (COM3) or IRQ3 (COM4) only after reading the following
guidelines:
If you need to use COM3 or COM4, keep the following in mind:
* The Courier supports three additional IRQs: IRQ2, IRQ5 and IRQ7.
Your software must support the one you use for COM3 or COM4. However,
if your computer is XT-compatible, IRQ5 is reserved for the hard disk,
and it is not available for a serial port. IRQ5 is available on 286-PCs
and higher.
* Two devices should not use the same IRQ at the same time, because there
will be a conflict and you will probably lose data. For example, if you
use IRQ4 for a mouse installed at COM1 and for your modem installed at
COM3 (as shown in the previous table) you cannot use the mouse and the
modem at the same time.
Additionally, if an installed device doesn't use IRQs, you can use the
IRQ normally associated with that COM port. For example, if you have a
serial printer at COM1 and you know it does not use an IRQ, you can use
IRQ4 at COM3. Similarly, you could use IRQ3 at COM4 if the device at
COM2 doesn't use IRQ3.
If you cannot find the information you need in your software documentation,
call your software's Technical Support Department for help in selecting an
IRQ. You may find it necessary to re-install your serial devices to
correctly allocate the available serial ports and IRQs.
*****************
Reset the Jumpers
If you hold the modem so that the rear panel is at the bottom and the edge
connector is at the left of the circuit board you can locate the COM and
IRQ jumpers near the center left side of the board.
Each jumper has two upright contacts connected by a black plastic piece,
called a shunt, placed over the contacts for the COM2 and IRQ3 settings.
This shunt selects the jumper by closing the circuit.
To change a jumper setting, gently lift off the black shunt and replace it
over the contacts you want.
As we've said, your choice of an IRQ for COM3 or COM4 depends on your
hardware/software configuration. If the device at COM1 or COM2 isn't
using IRQ4 or IRQ3, you may use one of them. Otherwise, check your PC
and software documentation to see if you may use IRQ2, IRQ5 or IRQ7.
WARNING: Do not select an IRQ position until you've read the previous
guidelines and reviewed your software documentation.
****************
Set DIP Switches
A ten-position bank of Dual In-Line Package (DIP) switches is located at
the rear of the modem. A summary of the DIP switch functions and options
is in Appendix B in this manual and on the Quick Reference Card.
WARNING: Check your software documentation for its requirements,
particularly for DIP switches 1, 4, 5 and 6.
NOTE: Once the modem is installed, the DIP switches are accessible
through the computer's rear panel.
********************
Installing the Modem
1. Turn off the computer and peripheral devices.
2. Remove the computer's cover. Refer to the computer manual, if
necessary, to see which rear panel screws to remove before sliding
the cover off.
NOTE: Our illustration shows expansion slots lined up vertically on
the floor of the computer. Some computers are configured so that the
expansion slots are stacked horizontally, one on top of another.
The following instructions apply for both configurations.
3. Unscrew the solid bracket at the back of any available expansion slot.
(The modem board requires at least a standard half-card slot.)
The bracket will pop out of the back, leaving an opening in the rear
panel for access to the modem's phone jacks and DIP switches.
4. Expansion slots have either a 3-inch-long groove, or a 3-inch and a
2-inch groove. These grooves are lined on both sides with metal guides.
Insert the modem board into the slot you've chosen, as in Figure 3.3,
with the leads on the modem board's edge connector firmly in the 3-inch
groove.
5. Screw the vertical bracket at the back of the modem firmly to the
computer's rear panel, as shown in Figure 3.3. This helps block radio
frequency emissions from the computer and keeps the modem board firmly
in place.
6. Replace the cover of the computer and replace the screws.
7. If you currently have a phone plugged into the wall jack, disconnect it.
Plug one end of the phone cable that came with the modem into the TELCO
jack at the rear of the modem. This allows the modem to switch into the
telephone network, get a dial tone, and so on. Plug the other end of
the cable into the wall jack.
NOTE: The phone cable is equipped with two standard, modular RJ11C
phone connectors. If you have an older type of wall jack, you can
purchase an adapter and RJ11C connector from your phone company or
computer dealer.
8. If you wish, plug your phone's cord into the second jack on the modem,
labeled PHONE. This enables you to use your phone for conventional
voice calls, and also allows you to switch between voice and data
transmission in the same call. See Voice/Data Communications in
Appendix G for more information.
************************
Testing the Installation
Use the following procedures to verify that your modem is working properly.
1. Turn on your computer. Then turn the Courier's power switch ON. The
following front panel indicators, or LEDs, will light up on the modem.
CD Carrier Detect, if you have set DIP switch 6 ON, enabling
the CD override
TR Data Terminal Ready, if you have set DIP switch 1 ON,
enabling the DTR override
MR Modem Ready/Power ON
CS Clear to Send
2. If you're using a personal computer, load your software to start the
program. Set your terminal or software to 19.2K bps or 9600 bps.
In addition, set a word length of either 7 bits plus 1 parity bit, or
8 bits with no parity<74>it doesn't matter which at this time<6D>and 1 Stop
bit. Set the software to use the correct serial port (port through
which the modem connects to the computer).
3. Perform the function that lets you send AT commands to the modem, that
is, puts the computer in Terminal mode. Some communications programs
do this automatically upon loading. Others require you to display a
communications or terminal screen, type a Function key, or perform some
other operation.
Review your communications software documentation for instructions.
4. Send the following attention command. Type either upper or lower case
letters, not a combination, and then press the Enter (Carriage Return)
key, shown in the example below between angle brackets. (Don't type
the angle brackets.)
AT <Enter>
If everything is correct, the modem responds as follows:
OK
Go on to step 5.
Troubleshooting
If your entered command is not displayed, your local echo is OFF. To turn
the local echo ON, send the modem the following command:
ATE1 <Enter>
If double characters appear on the screen, both your modem and software are
set to local echo ON. Either set your software to local echo OFF, or turn
the modem's echo OFF with the following command:
ATE0 <Enter>
If no OK appears on your screen after you completed Step 4, review the
following checkpoints:
a. Make sure you type all upper or lower case letters and press <Enter>.
b. Check to see that you set your communications software to the correct
serial port. The correct serial port is the port to which the modem is
connected to the computer.
c. Make sure your software has put the computer in Terminal mode, so that
you can send the modem commands. Then review Step 4, on the previous
page.
d. Be sure that DIP switches 1 and 6 are set ON or OFF according to your
terminal or software requirements. The table in Appendix B explains
each function, and you may also need to review your terminal or
communications software documentation.
e. If you set DIP switch 8 OFF, for Dumb mode, reset the modem to Smart
mode: set DIP switch 8 to ON.
f. The modem is shipped with DIP switch 3 ON, enabling the result codes.
If DIP switch 3 is OFF, set it to the ON position. Then initiate the
new switch setting with the following reset command:
ATZ <Enter>
5. As a final check, make sure the modem gets a dial tone. Type the
following Dial command:
ATD <Enter>
On receipt of the command, the modem goes off hook and waits for a dial
tone. The OH indicator lights up, and you'll hear the dial tone from
the modem's speaker. To cancel the operation, press any key.
Troubleshooting
If you don't hear the dial tone, first increase the volume by using the
L command. If that doesn't work, check to see that the phone cable from
the wall jack is connected to the correct jack on the modem. If
necessary, reconnect the phone cable correctly. Then try the Dial
command again, ATD <Enter>.
Chapter Four--Data Mode Operations
The information in this chapter applies to asynchronous calls only. For
synchronous operations, refer to Appendix F.
Detailed command descriptions are in this chapter. Additional command
summaries are in Appendix C, on the bottom panel of the modem, and in
the Quick-Reference Card.
*****************
COMMAND SET USAGE
The Courier command set enables you to send the modem two kinds of
instructions:
* operations, such as dialing or hanging up
* configurations, such as enabling error control or data compression
Follow these guidelines:
1. Your software must be loaded and, if you are using a computer, it must
be in Terminal mode.
Some communications programs put the computer in terminal mode
automatically when they are loaded. Others require you to display a
communications terminal screen, press a Function key, or perform some
other operation. Refer to your communications software documentation
for instructions.
In Terminal mode the computer acts as if it were a standard terminal
such as a teletypewriter, rather than a data processor. Keyboard
entries go directly to the modem, whether the entry is a modem command
or data to be transmitted over the phone lines. Received data is
output directly to the screen.
2. Type commands in either upper or lower case, not a combination (AT
or at--not At).
3. All commands except A/, A> and +++ are preceded by the AT (attention)
prefix and are executed with the Enter/Carriage Return key (<Enter>).
4. Command length = 60 characters maximum. The modem doesn't count the
AT prefix, Carriage Return character, or spaces. It counts (but
doesn't act on) punctuation such as hyphens and parentheses.
5. A missing numeric parameter is assumed to be zero, as in the command
to hang up: ATH <Enter> is the equivalent of ATH0 <Enter>.
Example (spaces are not required, but are added here for readability):
AT &K3 X2 DT 071 312 1234 <Enter>
AT Attention; a command follows.
&K3 Disable MNP5 data compression; use only V.42 bis compression.
X2 Use the X2 result code subset.
DT Dial the following number using tone dialing.
<Enter> Execute the commands.
This chapter groups related commands into the following categories.
* Basic Commands
* Dialing/Answering
Dialing
Dial Options
Cancel Dialing
Store Phone Numbers
Redialing
Answer Mode
Auto Answer
Hanging Up
* Setting/Using Defaults
Customizing NVRAM
Resetting the Modem
* Configuration:
Echo/Speaker
Result Codes
Modulation
Error Control/Data Compression
Data Rates
RS-232 Signal Operations
Flow Control
* S-Registers
* Inquiry and Help
* Testing
* International Calls
* Miscellaneous Commands
For an alphabetical listing of commands, check the first page of the index.
NOTE: The defaults listed are based on the modem's shipping configuration:
load from nonvolatile random access memory (NVRAM), DIP switch 10 OFF,
which is the same as the &F1 configuration template). For a complete
listing of default configuration templates, see Appendix B.
**************
BASIC COMMANDS
AT Attention command prefix. Use AT alone to test for the OK result
code. AT must prefix all commands except A/, A> and +++.
Any Terminate the current dialing operation resulting from an
key issued Dial command; terminate Repeat mode (> or A>).
*****************
DIALING/ANSWERING
Dialing
Dn Dial the specified phone number; also execute Dial options.
The maximum number of characters allowed is 60, including the AT
prefix, punctuation and spaces. The Carriage Return (Enter key)
isn't counted as a character.
NOTE: With the exception of the following Dial options, the
modem ignores any commands issued after D in the same command
string.
Dial Options
D Dial the number that follows and enter Originate mode. Optional
parameters:
P Pulse dial. Default.
T Tone dial.
, (Comma) Pause for 2 seconds before continuing to dial.
; Return to Command mode after dialing. If your phone is
plugged into the modem, you can use this option to have the modem
Auto Dial a telephone rather than a modem. The Courier dials,
remains off hook and returns the OK message, indicating it is in
Command mode.
For example, to have the modem place a voice call, enter the Dial
command with a semicolon:
ATDT5551234; <Enter>
When the modem returns the OK result, pick up your phone receiver
so you can talk to the other party, and send the command that
hangs up the modem:
ATH <Enter>
" Dial the letters that follow (in an alphabetical phone number).
NOTE: If you are including another command after the dial string,
use closing quotation marks before the additional command.
! Transfer a call (flash the switch-hook). This command applies to
modems in installations where other modems share the phone line.
The modem flashes the switch-hook (goes off hook 0.5 seconds, on
hook for 0.5 seconds and off hook again) to dial the specified
extension.
W This command is useful in situations where you must wait for a
second dial tone before continuing dialing. For example, if
you need to dial for an outside line, the Courier continues
dialing as soon as it detects the next dial tone.
AT DT 9 W 5551234 <Enter>
NOTE: This command executes only if result code option X3
or greater has been issued. If the modem is set to X2 or lower,
the modem interprets the W as a comma (two-second pause).
@ Wait for an answer (with X3 or higher). Some online services
answer the phone and return a tape-recorded request for
information before processing transactions. In such instances,
the @ command can be used in the Dial string to tell the modem
to detect at least one ring, wait for five seconds of silence
at the other end of the call, and then continue to execute the
Dial string.
To use the @ command, set the modem to X3, X4 or X7. If the
modem is set to X2 or lower, the modem returns an ERROR message
when encountering the @ character in a command string. If set
to X5 or X6, the modem hangs up when it detects a voice answer
and sends the VOICE result code.
/ A slash (/) causes a pause of only 125 milliseconds.
R Reverse frequencies. This command allows calls to an
originate-only modem. It reverses the modem's originate/answer
frequencies, forcing the Courier to dial out at the answer
frequency. The command follows the Dial command, before or
after the phone number:
AT D1234567R <Enter>
X2-X7 Adaptive dialing. When any of the X2 through X7 options is in
effect and you do not issue a dialing type in the Dial string,
the Courier uses tone dialing, which is faster than the default
pulse type. However, if the phone company's central office does
not have tone detection equipment, the modem cannot break dial
and continues to detect the dial tone. If this occurs, the
modem automatically reverts to pulse dialing.
DL Dial the last-dialed number. The modem stores each Dial command
until it receives the next Dial command. Use DL instead of A/,
described on the next page, if you wish to send the modem non-Dial
commands before dialing again.
DSn Dial the number stored in nonvolatile random access memory at
position n, where n = 0 through 9.
Cancel Dialing
To cancel Dial-command execution, press any key. If you
inadvertently hit a key on the keyboard while the modem is dialing,
the call is canceled. If this occurs, type the A/ command explained
under Automated Redialing below.
When the modem receives a command, it stores the instruction in
its command buffer until it receives the next AT command. Note
that if you've sent the modem an additional command since the Dial
command, A/ re-executes that command instead of redialing.
Store Phone Numbers
&Zn=s This command stores up to ten numbers, where n is the position
0 through 9 in nonvolatile memory, and s is the phone number string.
The number-string may be up to 40 characters long, including any
Dial command options.
AT &Z2=555-6789 <Enter>
Do not include modem settings in the &Zn string. If the call
requires a special setting, insert it in the command string before
the DSn command. In the following example, &M0 (no error control)
is inserted before the Dial command:
AT&M0 DS2 <Enter>
NOTE: The &Zn=s command functions differently when Dial Security
is enabled. See Appendix D for more information.
&Zn? Display the phone number stored in NVRAM at position n
(n = 0 through 9).
Redialing
A/ Re-execute the last issued command. A/ doesn't take the AT prefix
or a Carriage Return, and can be used to redial.
A/
Automated Redialing (>, A>)
While > and A> can be used to continuously repeat any command,
they are designed for automated redialing.
Enter Repeat Mode
> If you know the modem you are calling is frequently busy,
include the Repeat command in the Dial string, as follows:
AT > DT 1234567 <Enter> or
AT DT 1234567 > <Enter>
The modem enters Repeat mode, dials the number, waits 60 seconds
for a carrier (default), and hangs up. Then after a two-second
pause, it redials.
The cycle continues until the modems connect or the modem reaches a
maximum of 10 attempts. The 10-try limit is mandated by Industry
Canada (IC) to prevent tying up local telephone company exchanges
with unconnected calls.
A> This command combines the features of both the A/ and > commands.
The modem enters Repeat mode as described above, and redials the
Dial string in the command buffer. Like the A/ command, A> does
not take the AT prefix or a Carriage Return.
Exit Repeat Mode
Should you use > or A> with a command other than a Dial string,
abort the cycle by pressing any key.
To abort automated redialing, be sure to press any key when the
result code appears, during the pause before the modem begins
dialing again. If you press any key while the modem is dialing,
that dial attempt is canceled but the cycle continues.
Answer Mode
Force Answer Mode
A Force Answer mode when the modem hasn't received an incoming call.
Auto Answer
The Courier is shipped with DIP switch 5 ON, Auto Answer suppressed.
To set the modem to automatically answer incoming calls, do one of
the following:
1. Before powering on the modem, set DIP switch 5 OFF. When you
turn the computer on, the modem answers incoming calls on the
first ring.
2. When the modem is on, set your communications software to enable
auto answer. The following command instructs the modem to answer
on the first ring. (You can substitute a higher value. See the
S-Register summary in Appendix B.)
AT S0 = 1 <Enter>
When the modem senses a call coming in, it sends the result code
RING to your screen, goes off hook, and sends the remote modem a
high-pitched answer tone. If there is no Carrier Detect within
60 seconds, the modem hangs up. If the connection is made, the
modem sends a CONNECT result code. When the call is disconnected
by you or the remote user, the modem hangs up and returns the NO
CARRIER code.
NOTE: If DIP switch 5 is OFF and S0=0, the Auto Answer will be
disabled. Be sure that S0=1 through 256.
Suppressing Auto Answer
To disable Auto Answer, reverse Steps 1 or 2 above. Set DIP switch
5 ON before powering on the modem, or set the modem to answer on
zero rings with the following command.
AT S0 = 0 <Enter>
Points to Remember
1. If the modem is attached to a computer, you can set the modem to
receive calls when you're not at your computer. Load your
communications software as you normally do, and set the modem
to Auto Answer. Also set your software's host mode function
to save incoming messages and/or files.
2. If you've attached your phone so it can be used for conventional
calls, disable Auto Answer when you are not expecting incoming
data calls. Otherwise, your modem may answer the phone before
you do, greeting a voice caller with a high-pitched answer tone.
Hanging Up
Hn On/off hook control.
H0 Hang up (go on hook).
H1 Go off hook.
+++ Escape code operations. Once the modem is online to another system,
the only command it recognizes is an escape code of three typed
pluses, which forces the modem back to Command mode.
Do the following when issuing the command:
* Wait one second after sending the last item of data
* Type: +++
* Wait one second before typing any data
Do not type the AT prefix or a Carriage Return. The guard time of
one second before and after the code prevents the modem from
misinterpreting the occurrence of +++ in the transmitted data stream.
If necessary, the character used in the escape code or the duration
of the guard time can be changed by resetting Register S2 or S12.
See the S-Register Summary in Appendix B.
In response to +++, the modem returns to Command mode. However,
it keeps the line open or hangs up, depending on the setting of
DIP switch 9:
DIP Switch 9 Response to +++
OFF Modem goes on hook (hangs up), sends NO CARRIER
result code (factory setting)
ON Modem maintains connection (Online-Command mode),
sends OK result code
The factory setting (OFF) forces an automatic disconnect when you
issue +++. One advantage of this is that you are not likely to
inadvertently run up an all-night phone bill.
Set DIP switch 9 ON if you want the modem to respond to +++ by
entering Online-Command mode, enabling it to execute commands and
return online. (See the O command, next.)
WARNING: For unattended modem operations: in rare instances, the
modem may fail to recognize the +++ escape code sequence. If you
are running the modem under software control for unattended
operations, we suggest you use the sure fire method of dropping the
DTR signal from the computer or terminal for at least 50
milliseconds, to avoid costly phone charges. Methods of turning
the DTR signal off--for example, closing the communications port--
differ from one computer to another.
Returning Online
On If DIP switch 9 is ON (on detection of the escape code the modem
maintains the connection), you can issue commands and then toggle
the modem back online with the On command, as in this example:
AT Q1 O <Enter>
There are two ways to return online.
ATO0 Return online (normal). (Used in the example above.)
ATO1 Return online and retrain. Use to have the modem
re-synchronize if there were errors in a non-ARQ data
transfer.
Hanging Up
If DIP switch 9 is ON, the escape code forces the modem back to
Command mode but leaves the line open. If you want the modem to
hang up, issue the following command once the modem sends the
OK result code:
ATH <Enter>
If DIP switch 9 is OFF, the modem automatically hangs up on receipt
of the escape code.
**********************
SETTING/USING DEFAULTS
The modem's read-only memory (ROM) permanently stores the modem's four
factory template settings. Nonvolatile random access memory (NVRAM)
allows you to save one of these four templates, or add your own
modifications, and write all the settings to NVRAM as your power-on
defaults.
&Fn The modem is shipped with four configurations (templates),
&F0 through &F3, stored in permanent nonprogrammable memory (ROM).
Appendix B includes configuration listings for each template.
Any one of the templates may be loaded into current memory (AT &Fn)
or written to nonvolatile memory to serve as the reset default
(AT &Fn &W). Note, however, that &F0 is always loaded into memory
if DIP switch 10 is ON.
When you power on the Courier, it loads the settings stored in
NVRAM if DIP switch 10 is OFF. Until you write your own settings
to NVRAM, the defaults stored there are the same as the permanent
ROM factory settings stored in position 1, &F1.
To view the &F1 settings, select option 5 of the I (inquiry) command:
AT I5 <Enter>
Customizing NVRAM
&W To substitute a template other than &F1, write the desired template
to NVRAM, using the &W command.
AT &F2 &W <Enter>
To modify the &Fn configuration in NVRAM, type your changes and
then save them to NVRAM, as in the following example. The original
factory template remains intact.
AT M2 S10=40 &A2 &W <Enter>\
NOTE: When writing a different default configuration to NVRAM,
insert any additions after the &Fn command but before &W. Otherwise
they will be overwritten by &Fn.
After sending a configuration to NVRAM, you can change any setting
just for the current session, as in the following example. The
NVRAM configuration remains intact.
ATX6 <Enter>
But if you want the new setting to be a default, write it to
NVRAM at the same time, as in the following example. X7 is
substituted for the Xn value stored earlier. Any other setting
that was changed and can be saved to NVRAM will also be saved.
AT X7 &W <Enter>
Resetting the Modem
Z Software reset to NVRAM settings when DIP switch 10 is OFF (factory
setting). If DIP switch 10 is OFF, the modem resets to the &F0
configuration template, with no flow control.
NOTE: Use the ATZ command also if you've changed the position of
DIP switches 1 through 7 or 9 while the modem is on, so that the
modem can read the new setting. The only other way to initiate
a new setting for switches 1 through 7 and 9 is to turn the modem
off and on again.
*************
CONFIGURATION
Echo/Speaker
En Command mode local echo. Enables/disables the display of your
typed commands. If double characters appear on the screen, both
the modem's local echo and your software's local echo are on.
The Courier is shipped with DIP switch 4 OFF, enabling local echo.
The En command controls the local echo for a current session,
independently of the switch setting. At power-on and reset, the
modem operates according to the DIP switch setting. The En command
is not stored in nonvolatile memory as a power-on/reset default.
E0 Command mode echo OFF. The modem does not display keyboard
commands.
E1 Command mode echo ON.
Fn Online local echo. This command causes the modem to display a copy
of the data it is transmitting to another system. Many systems,
however, return a copy of received data, which is called a remote
echo. If the modem's online echo is ON and there is also remote
echoing, double characters appear on the screen.
In some microcomputer documentation, the term duplex is applied to
local online echoing, although the term is not technically accurate.
F0 Online echo ON. Sometimes called half duplex. As the
modem transmits data to a remote system, it also sends a
copy of the data to the screen.
F1 Online echo OFF. Sometimes called full duplex. Default.
Mn Speaker (audio monitor).
M0 The speaker is always OFF.
M1 The speaker is ON until carrier is established. Default.
M2 The speaker is always ON, including during data transfer.
M3 The speaker is ON after the last digit is dialed and remains
ON until carrier is established.
Result Codes
Qn Enable/suppress the display of result codes. The Courier is
shipped with DIP switch 3 ON, to display result codes. Use the
Qn command to control the display for a current session,
independently of the switch setting.
At power-on and reset, the modem operates according to the DIP
switch setting. The Qn command is not stored in nonvolatile
random access memory.
Q0 Result codes displayed.
Q1 Result codes suppressed (quiet).
Q2 Result codes suppressed in Answer mode.
Vn Return result codes in words or numbers (Verbal/Numeric mode).
At power-on and reset, the modem operates according to the DIP
switch setting. The Vn command is not stored in nonvolatile
memory as a power-on/reset default.
V0 Numeric mode.
V1 Verbal mode.
Xn Result code set options. Use the following table (Default = X7,
all codes except 12/VOICE). For result codes for synchronous
operations, see Appendix F.
Setting
Result Codes X0 X1 X2 X3 X4 X5 X6 X7
0/OK <20> <20> <20> <20> <20> <20> <20> <20>
1/CONNECT <20> <20> <20> <20> <20> <20> <20> <20>
2/RING <20> <20> <20> <20> <20> <20> <20> <20>
3/NO CARRIER <20> <20> <20> <20> <20> <20> <20> <20>
4/ERROR <20> <20> <20> <20> <20> <20> <20> <20>
5/CONNECT 1200 <20> <20> <20> <20> <20> <20> <20>
6/NO DIAL TONE <20> <20> <20> <20>
7/BUSY <20> <20> <20> <20> <20>
8/NO ANSWER <20> <20> <20> <20> <20>
9/RESERVED
10/CONNECT 2400 <20> <20> <20> <20> <20> <20> <20>
11/RINGING <20> <20> <20>
12/VOICE <20> <20>
13/CONNECT 9600 <20> <20> <20> <20> <20> <20> <20>
18/CONNECT 4800 <20> <20> <20> <20> <20> <20> <20>
20/CONNECT 7200 <20> <20> <20> <20> <20> <20> <20>
21/CONNECT 12000 <20> <20> <20> <20> <20> <20> <20>
25/CONNECT 14400 <20> <20> <20> <20> <20> <20> <20>
43/CONNECT 16800 <20> <20> <20> <20> <20> <20> <20>
85/CONNECT 19200 <20> <20> <20> <20> <20> <20> <20>
91/CONNECT 21600 <20> <20> <20> <20> <20> <20> <20>
99/CONNECT 24000 <20> <20> <20> <20> <20> <20> <20>
103/CONNECT 26400 <20> <20> <20> <20> <20> <20> <20>
107/CONNECT 28800 <20> <20> <20> <20> <20> <20> <20>
Functions
Adaptive Dialing <20> <20> <20> <20> <20> <20>
Wait for 2nd Dial Tone (W) <20> <20> <20> <20> <20>
Wait for Answer (@) <20> <20> <20> <20> <20>
Fast Dial <20> <20> <20> <20>
NOTE: Additional messages indicate an error control connection and the
modulation for a call. See the next section, Additional Result Code
Subsets.
Result Code Meaning
0/OK Command has been executed.
1/CONNECT Connection with another modem; if set to X0, connection may
be between 300 and 28.8 bps; if X1 or higher, connection is
at 300 bps.
2/RING Incoming ring detected.
3/NO CARRIER Carrier detect has failed or carrier has been dropped due to
disconnect.
4/ERROR Command is invalid.
5/CONNECT 1200 Connection with another modem at 1200 bps.
6/NO DIAL TONE Dial tone not detected during the normal 2 seconds, set in
Register S6.
7/BUSY Busy signal detect; modem hangs up.
8/NO ANSWER After waiting 5 seconds for an answer, modem hangs up;
returned instead of NO CARRIER when the @ option is used.
10/CONNECT 2400 Connection with another modem at 2400 bps.
11/RINGING The modem has dialed; remote phone line is ringing.
12/VOICE Voice answer at remote site; modem hangs up.
13/CONNECT 9600 Connection at reported rate. Same meaning for results of
4800 (18), 7200 (20), 12K (21), 14.4K (25), 16.8K (43),
19.2K (85), 21.6K (91), 24K (99), 26.4K (103), or 28.8K (107)
Adaptive The modem attempts to use tone dialing and, if that
Dialing doesn't work, reverts to rotary dialing.
Wait for The modem continues dialing as soon as it detects
Another Dial another dial tone. See the dial options earlier in this
Tone (W) chapter.
Wait for an The modem continues dialing when it detects 5 seconds of
Answer (@) silence on the line. See the dial options earlier in this
chapter.
Fast Dial The modem dials immediately on dial-tone detect, instead of
waiting the normal 2 seconds set in Register S6.
Additional Result Code Subsets
NOTE: ARQ (Automatic Repeat Request) is used in this manual to denote
calls under error control.
&An Enable/disable additional result code subsets. See the Xn
command earlier in this chapter.
&A0 ARQ result codes are disabled. This setting does not affect
an error control connection; the modem returns the standard
CONNECT messages if result codes are enabled.
&A1 ARQ result codes are enabled, indicating that a connection
is under error control. Message 14 is displayed if the
modem is set to X0 and the connection is at any rate from
1200 to 28.8K bps. The remaining results indicate the
connection rate and require a setting of X1 or higher.
14/CONNECT/ARQ 47/CONNECT 16800/ARQ
15/CONNECT 1200/ARQ 88/CONNECT 19200/ARQ
16/CONNECT 2400/ARQ 94/CONNECT 21600/ARQ
17/CONNECT 9600/ARQ 100/CONNECT 24000/ARQ
19/CONNECT 4800/ARQ 104/CONNECT 26400/ARQ
22/CONNECT 12000/ARQ 108/CONNECT 28800/ARQ
24/CONNECT 7200/ARQ
26/CONNECT 14400/ARQ
&A2 Additional VFC, V34, HST, or V32 modulation indicator.
Included for users of HST Dual Standard modems. If your
software cannot handle the added modulation information,
select &A1 or &A0.
23/CONNECT 9600/HST 27/CONNECT 9600/ARQ/HST
28/CONNECT 4800/HST 29/CONNECT 4800/ARQ/HST
30/CONNECT 7200/HST 34/CONNECT 7200/ARQ/HST
31/CONNECT 12000/HST 32/CONNECT 12000/ARQ/HST
35/CONNECT 14400/HST 36/CONNECT 14400/ARQ/HST
53/CONNECT 16800/HST 57/CONNECT 16800/ARQ/HST
33/CONNECT 9600/V32 37/CONNECT 9600/ARQ/V32
38/CONNECT 4800/V32 39/CONNECT 4800/ARQ/V32
40/CONNECT 7200/V32 44/CONNECT 7200/ARQ/V32
41/CONNECT 12000/V32 42/CONNECT 12000/ARQ/V32
45/CONNECT 14400/V32 46/CONNECT 14400/ARQ/V32
83/CONNECT 16800/V32 84/CONNECT 16800/ARQ/V32
87/CONNECT 19200/V32 90/CONNECT 19200/ARQ/V32
93/CONNECT 21600/V32 96/CONNECT 21600/ARQ/V32
97/CONNECT 21600/VFC 98/CONNECT 21600/ARQ/VFC
101/CONNECT 24000/VFC 102/CONNECT 24000/ARQ/VFC
105/CONNECT 26400/VFC 106/CONNECT 26400/ARQ/VFC
109/CONNECT 28800/VFC 110/CONNECT 28800/ARQ/VFC
139/CONNECT 14400/VFC 141/CONNECT 14400/ARQ/VFC
143/CONNECT 16800/VFC 145/CONNECT 16800/ARQ/VFC
147/CONNECT 19200/VFC 149/CONNECT 19200/ARQ/VFC
111/CONNECT 21600/V34 112/CONNECT 21600/ARQ/V34
113/CONNECT 24000/V34 114/CONNECT 24000/ARQ/V34
115/CONNECT 26400/V34 116/CONNECT 26400/ARQ/V34
117/CONNECT 28800/V34 118/CONNECT 28800/ARQ/V34
120/CONNECT 2400/V34 122/CONNECT 2400/ARQ/V34
124/CONNECT 4800/V34 126/CONNECT 4800/ARQ/V34
128/CONNECT 7200/V34 130/CONNECT 7200/ARQ/V34
132/CONNECT 9600/V34 134/CONNECT 9600/ARQ/V34
136/CONNECT 12000/V34 138/CONNECT 12000/ARQ/V34
140/CONNECT 14400/V34 142/CONNECT 14400/ARQ/V34
144/CONNECT 16800/V34 146/CONNECT 16800/ARQ/V34
148/CONNECT 19200/V34 150/CONNECT 19200/ARQ/V34
&A3 Additional error control indicator (LAPM, HST, MNP, SYNC, or
ONE) and data compression type (V42BIS or MNP5). Default.
When the call is not under one of those protocols (and ARQ
is not included in the result code), the modem reports
either SYNC, indicating a synchronous connection, or
NONE, for no protocol.
If the modems are using data compression, the type of
compression, V42BIS or MNP5, is added to the result code.
In the first of the following examples, the modems
negotiated error control for the call (ARQ), used VFC
modulation, are using the LAPM error control protocol, and
are using V.42 bis compression.
CONNECT 28800/ARQ/VFC/LAPM/V42BIS [or MNP/MNP5]
CONNECT 19200/ARQ/V32/LAPM/V42BIS [or MNP/MNP5]
CONNECT 16800/ARQ/HST/HST/V42BIS [or MNP/MNP5]
CONNECT 14400/ARQ/V32/LAPM/V42BIS [or MNP/MNP5]
CONNECT 9600/ARQ/HST/CELLULAR/HST/V42BIS [or MNP5]
CONNECT 9600/SYNC
CONNECT 2400/NONE
NOTE: Although these codes will return numeric identifiers,
they are the same numeric identifiers used for &A2 result
codes. If the modem is in Numeric mode (V0) and set to
&A3, you will not be able to differentiate between &A2 and
&A3 result codes. &A3 result codes may not be compatible
with some software.
Modulation
Bn Handshake options. There are three commands that apply to
international calls above 1200 bps--Bn, &Gn, &Pn. See International
Calls later in this chapter for information on the other two
settings.
B0 ITU-T (formerly CCITT) answer sequence. Default. This
is required to answer all V.32-type calls, as well as
calls from overseas.
B1 Bell answer tone. This setting selects HST modulation
in Dual Standard modems, but should only be used if the
modem is not required to answer V.32-type calls.
NOTE: This setting is required for HST cellular calls.
Error Control/Data Compression
&Mn Enable ARQ (error control) or synchronous protocols. Both your
modem and the remote modem must use the same protocol.
&M0 Normal mode, no error control. Due to the nature of phone
line channels, this is never recommended for calls above
2400 bps.
&M1 This setting is exclusive of the modems' error control and
is used only for online synchronous mode without V.25 bis.
See Appendix F for more information.
&M2 Reserved.
&M3 Reserved.
&M4 Normal/ARQ mode. Default. If an ARQ connection isn't made,
the modem operates in Normal mode, as though it were set to
&M0.
NOTE: When V.32-type modems revert to Normal mode, they
transfer data at high speeds without the reliability
of error control. To avoid this, both local and remote
modems should always be set for error control. Modems in
HST mode, if unable to establish an error control connection,
drop to 2400 bps.
&M5 The modem enters ARQ asynchronous mode. The modem hangs up
if an ARQ connection cannot be made.
&M6 The modem enters V.25 bis synchronous mode, using a
character-oriented link protocol similar to BISYNC. See
Appendix F for more information.
&M7 The modem enters V.25 bis synchronous mode, using the HDLC
link protocol.
&Kn Enable/disable data compression.
&K0 Data compression disabled.
&K1 Auto enable/disable. Default. The modem enables
compression if the serial port rate is fixed, &B1. It
disables compression if the serial port rate follows the
connection rate, &B0, because compression offers no
throughput advantage when the serial port and connection
rates are equal. Compression may even degrade throughput.
&K2 Data compression enabled. Use this setting to keep the
modem from disabling compression.
&K3 Selective data compression. The modem negotiates only for
V.42 bis compression, and disables MNP Level 5 (MNP5)
compression. Use this setting to transfer 8-bit binary
files, .ZIP files, and other files that are already
compressed. See the note below.
NOTE: MNP5 compression is not useful when transferring
files that are already compressed, such as the .ZIP files
downloaded from many Bulletin Boards and 8-bit binary files,
which appear to the modem to be compressed. MNP5 tends to
add data to the transmission so that throughput over the
link degrades. V.42 bis compression dynamically detects
when data is already compressed and turns off until it
detects that compression will work to advantage. The
special &K3 setting enables the best throughput for already-
compressed files.
See Throughput Guidelines and Data Compression in Appendix A for
more information, including throughput to expect for different
kinds of files.
Data Rates
The modem can be set to a fixed or variable serial port rate. A fixed rate
sets the modem for the highest possible throughput and provides the best
performance. A variable rate allows the modem to switch to match the more
limited rate on the phone connection.
Your software must support fixed or variable serial port rates, and must be
set to either of the two settings. NOTE: Your software may refer to these
options with terms like locked serial port (fixed rate) or autobaud (variable
rate).
&Bn Serial port rate variable or fixed.
&B0 Variable rates. When the modem switches its connection rate
to connect with a modem operating at a different rate, it
also switches its serial port rate. The software or
terminal also switches serial port rates to match the
connection rate.
&B1 Fixed rate. Default. The modem always communicates with
the terminal or computer at the rate at which you have set
the terminal or software, regardless of the connection rate.
For the greatest throughput, set the serial port to 115.2K,
57.6K, 38.4K bps for high speed calls and to at least 9600
bps for 2400-bps calls.
This setting is not affected by the &N setting. However,
the serial port rate must be equal to or higher than the &Nn
rate.
&B2 Fixed for ARQ calls/Variable for non-ARQ calls. Answer mode
only. When the modem goes off hook and connects in ARQ
mode, it shifts its serial port rate up to a user-specified
rate, for example, 38.4K bps. If the connection is not
under error control, the modem behaves as if it were set
to &B0 and switches its serial port rate to match the
connection rate of each call.
To implement this feature, first set your software to the
desired rate. Then send the modem the AT &B2 [other
settings] &W command.
The modem stores the rate of the command in NVRAM along
with the settings. Each time it makes an ARQ connection,
the modem checks NVRAM for the specified serial port rate.
When sending subsequent configurations to NVRAM, be sure
your software is set to your selected serial port rate,
so that the correct rate is maintained.
&Nn Connection rate variable or fixed.
&N0 Variable rates. Default. The Courier negotiates with
the remote modem for the highest possible connection rate,
depending on the capabilities of the remote modem.
&N1- Fixed rate. The modem only connects if the remote
&N14 modem is operating at the same rate. If not, the modem
hangs up. If you wish, you can filter out calls at other
than a specific rate, for security or other reasons, by
fixing the connection rate.
The connection rate must always be lower than, or equal to,
the serial port rate, never higher.
The options are as follows.
&N1 300 bps &N8 14.4K bps
&N2 1200 bps &N9 16.8K bps
&N3 2400 bps &N10 19.2K bps
&N4 4800 bps &N11 21.6K bps
&N5 7200 bps &N12 24K bps
&N6 9600 bps &N13 26.4K bps
&N7 12K bps &N14 28.8K bps
************************
RS-232 Signal Operations
&Cn Carrier Detect operations. At power-on and reset, the modem
operates according to the setting of DIP switch 6. This command
is not stored in nonvolatile memory as a power-on/reset default.
&C0 CD override, CD always ON.
&C1 Normal CD operations. The Courier sends a CD signal when
it connects with another modem and drops the CD when it
disconnects.
&Dn Data Terminal Ready (DTR) operations. At power-on and reset,
the modem operates according to the setting of DIP switch 1.
This command is not stored in nonvolatile memory as a
power-on/reset default.
&D0 DTR override. The modem operates as though the DTR is
always ON.
&D1 Advance usage: If issued before connecting with another
modem, the modem can enter online command mode during a
call by toggling DTR. (Most communications software
packages have a method for toggling DTR.) &D1 functions
similarly to the escape code (+++), except that this setting
is independent of DIP switch 9.
If DIP Switch 1 is ON (DTR override) when you issue the
&D1 command, the DTR override is automatically turned off.
However, if you change the setting of DIP switch 1 after
issuing &D1, the DIP switch setting takes precedence.
Return online with the On command, or hang up with the Hn
command.
&D2 Normal DTR operations. The terminal or computer must send
a DTR signal for the modem to accept commands. Dropping
DTR terminates a call.
&Sn The modem sends the computer or terminal a Data Set Ready (DSR)
signal via the RS-232 interface. (Data Set is industry jargon for
modem.) Few, if any, commercial communications programs require
the modem to control DSR, &S1. Leave the modem set for DSR
overridden, &S0, unless you know that your installation requires
a different setting.
&S0 DSR is always ON (override). Default.
&S1 In Originate mode, the modem sends the DSR after it
dials, when it detects the remote modem's answer tone.
In Answer mode, the modem sends the DSR after it sends an
answer tone.
&S2 This option is for specialized equipment such as automatic
callback units. On loss of carrier, the modem sends a
pulsed DSR signal with Clear to Send (CTS) following
Carrier Detect (CD).
&S3 This is the same as &S2, but without the CTS following CD.
&S4 The modem sends the computer a DSR signal at the same time
that it sends the Carrier Detect (CD) signal.
&S5 CTS follows Carrier Detect with SSR normal
************
Flow Control
Flow control allows the modem to monitor the amount of data coming from the
computer or the remote modem, and notify either end if its buffers are too
full, so that they stop sending data for a moment.
The modem uses either hardware or software flow control. Your software and
machine must support whichever type you select.
Hardware Control
The modem drops the Clear to Send (CTS) signal it's been sending to the
computer or terminal when the modem's buffer nears 90% capacity. It starts
sending CTS again when the buffer is about half full.
Software Control
The modem sends the computer or terminal the standard ASCII Transmit OFF
(XOFF) character, <Ctrl>-S, when its buffer nears 90% capacity. The modem
sends the ASCII Transmit ON character, <Ctrl>-Q, when the buffer is about
half full. ASCII definitions are as follows:
XON <Ctrl>-Q (ASCII 17 Decimal, 11 Hex)
XOFF <Ctrl>-S (ASCII 19 Decimal, 13 Hex)
NOTE: You should set your software as well to either hardware or software
flow control. Some programs also require that you turn off the type you are
not using.
The ASCII characters may be user-defined. See Registers S22 and S23 in
Appendix B. That appendix also includes an ASCII chart.
WARNING: If possible, always use hardware flow control, the factory
default. You may lose data if XON/XOFF (<Ctrl>-S, <Ctrl>-Q) characters
occur in the data stream from other sources. They may, for example, come
from the remote system: an XON from the remote system, after your modem
has sent an XOFF, can result in buffer overflow.
<Ctrl>-S (XOFF) and <Ctrl>-Q (XON) characters also occur in binary files,
and are used by Xmodem-type protocols. You risk having these characters
misinterpreted as modem flow control characters and dropped from the data
stream.
If you cannot use hardware flow control and if you're transferring non-text
(binary) files, or using an Xmodem-type protocol, disable flow control
entirely (&H0). In addition, be sure the modem is set to &B0 and &N0, so
that the serial port and connection rates are equal.
Transmit Data Buffer Sizes
The Transmit Data refers to the data from the computer, which the
modem is to transmit over the phone line.
The size of the Transmit data buffer depends on whether the connection
is under error control or not, as follows.
* ARQ connections: 3.25K bytes.
* Non-ARQ connections: 1.5K bytes, allowing use of error control file
transfer protocols such as Xmodem and Ymodem without flow control.
If bit 3 of Register S15 is turned on, the non-ARQ buffer size is
reduced to 128 bytes, for the convenience of BBS operators taking
calls from remote users of slower modems. See S-Register Summary,
S15, in Appendix B.
Received Data Buffer Size
Received Data refers to the data the modem receives over the phone
link, which the modem passes on to the attached computer.
The size of this buffer remains constant at 2K bytes.
Transmit Data Flow Control
&Hn This type of flow control is for data transmitted to the modem by
its attached computer or terminal. The modem monitors its buffer
as data comes from the computer or modem. If the buffer approaches
90% capacity, the modem signals the computer or terminal to stop
transmitting. When the modem has sent enough data over the link
to half empty the buffer, it signals the computer or terminal to
resume transmitting.
&H0 Transmit Data flow control disabled.
&H1 Hardware flow control. Default. Requires that your
computer or terminal and software support Clear to Send
(CTS) at the RS-232 interface.
&H2 Software flow control. Requires that your software
support XON/XOFF signaling.
&H3 Use both hardware and software flow control. If you are
unsure about what your equipment supports, select this
option. But keep the warning, above, in mind about software
flow control.
Received Data Flow Control
Separate commands, &Rn (hardware) and &In (software), control the flow of
Received Data passed by the Courier to your computer or terminal.
Your software and machine must support whichever type you select, although
we recommend hardware flow control, if possible.
Hardware Control(&Rn)
&R0 Delay Clear to Send Response after Request to Send signal
(RTS/CTS delay). The delay is required by some synchronous
mainframes and does not apply to asynchronous calls.
&R1 The modem ignores RTS. This setting is required if your
computer or terminal or software does not support RTS.
&R2 Hardware flow control of received data enabled. Default.
The modem sends data to the computer or terminal only on
receipt of the RTS signal.
Software Control (&In)
WARNING: In ordinary operation, the only characters the modem
recognizes during a call are the three pluses (+++) of the escape
code. But when software flow control is enabled, the modem also looks
for <Ctrl>-S or <Ctrl>-Q characters. If these characters occur in a
file or as part of a protocol, the modem reads them as XON/XOFF
characters and acts on them. In some cases, the modem drops them
from the data stream.
&I0 Disables XON/XOFF flow control of received data. Default.
Recommended for non-ARQ (Normal mode) calls, but see &I5.
The I0 option provides transparency for all characters except
the escape code sequence (+++), because at this setting the
modem does not look for control characters.
NOTE: Because of the risk described in the above warning, the
settings that follow are only recommended for users whose data
does not include XON/XOFF control characters.
&I1 The Courier acts on your typed XON/XOFF commands, <Ctrl>-S or
<Ctrl>-Q, and passes them to the remote computer. Use in ARQ
mode only, but keep in mind that the XON/XOFF characters sent
to the remote computer may interfere with XON/XOFF signaling
between the remote computer and remote modem. See &I2.
&I2 The Courier acts on your XON/XOFF commands, but removes them
from the data stream instead of passing them to the remote
computer. This ensures that the remote computer does not
confuse your XON/XOFF characters with those from its attached
modem. This is the recommended setting for ARQ mode.
However, if the call is not in ARQ mode, there is no flow
control on the phone link. If you send an XOFF to your modem
and it stops passing data, it has no way to tell the remote
computer and modem to stop sending for a while, and your
modem's buffer may overflow. For more reliable control in
non-ARQ mode, see &I5.
&I3 Hewlett PackardSYMBOL 190 \f "Symbol"Host mode. Applies only
to modems attached to an HP mainframe that uses the ENQ/ACK
protocol. Use in ARQ mode only. See Appendix G.
&I4 Hewlett PackardSYMBOL 190 \f "Symbol"Terminal mode. Applies
only to modems attached to terminals in an HP system that uses
the ENQ/ACK protocol. Use in ARQ mode only. See Appendix G.
&I5 This setting is designed to enable flow control on the phone
link when the connection is not under error control. For this
to work for you, the remote modem must also have &I5 capability.
In ARQ mode, a Courier set to &I5 operates the same as it does
when set to &I2. It acts on your XON/XOFF commands, but does
not pass them to the remote system. The error control protocol
enables the modems to control the flow of data on the phone
link.
In non-ARQ mode, a Courier set to &I5 operates as though flow
control were disabled (&I0); it does not look for your typed
XON/XOFF commands. However, it looks for XON/XOFF characters
coming in over the phone link. When the remote operator sends
XON/XOFF commands, the Courier either resumes or stops
transmitting data over the link and drops the characters from
the data stream.
If both modems are set to &I5, operators at each end can signal
the remote modem to stop sending, thereby controlling the data
flow on the phone link and preventing their own modem's buffer
from overflowing. At the computer or terminal/modem
interfaces, the modems independently control the flow of
data through their Transmit Data (&H) settings.
Guidelines
Use of software flow control may prove satisfactory if you're only
transferring text files. However, if you're transferring non-text
(binary) files, or using an Xmodem-type protocol, disable flow control
entirely (&R1, &I0). In addition, set the modem to &B0 and &N0, so
that the serial port and connection rates are equal.
***********
S-REGISTERS
The S-Registers are used to set various timing parameters, redefine selected
ASCII characters, and other configuration options. A detailed summary of
the S-register functions is in Appendix B. A less detailed summary is in
the Quick-Reference card.
Sr=n Set S-Register value: r is any S-Register; n must be a decimal
number between 0 and 255.
Sr.b=n Alternative command for setting bit-mapped registers: r is the
bit-mapped register; .b is the bit; n is 0 (off) or 1 (on).
Sr? Query contents of register r.
****************
INQUIRY AND HELP
The modem displays information such as the current modem settings, product
code, and call duration. It also displays summary information for every
command that the modem supports.
For more information on Inquiry and Help commands, including sample
displays, see Chapter 6.
*******
TESTING
The modem can perform a number of tests including Analog Loopback, Digital
Loopback, and Remote Digital Loopback. These tests can be used to check
the operations of the modem's transmitter and receiver, or to locate a
problem with a remote modem or telephone channel. Error control must be
disabled for these tests.
See Appendix H for more information.
*******************
INTERNATIONAL CALLS
There are three commands that apply to international calls above 1200
bps--Bn, &Gn, &Pn. Bn is described earlier in this chapter.
&Gn This setting applies only to overseas calls at 2400 or 1200 bps.
British phone switching systems require the modem to send an 1800
Hz guard tone after it sends an answer tone. Some other European
phone networks require a 550 Hz guard tone. Guard tones are not
used in the United States or Canada.
&G0 No guard tone. This is used in the U.S. and in Canada.
Default.
&G1 This sets a 550 Hz guard tone, and is used in some European
countries.
&G2 This sets an 1800 Hz guard tone, and is used in the U.K.
and some Commonwealth countries. &G2 requires the B0
setting.
&Pn This command sets the ratio of the off-hook/on-hook (make/break)
interval for pulse dialing. The default sets the modem for use in
North America. The ratio must be changed if the modem is used
in the United Kingdom and some Commonwealth countries.
&P0 Make/break ratio, U.S./Canada: 39%/61%. Default.
&P1 Make/break ratio, United Kingdom, some Commonwealth
countries: 33%/67%.
**********************
MISCELLANEOUS COMMANDS
Cn Transmitter enabled/disabled.
C0 Transmitter disabled; receive-only condition.
C1 Transmitter enabled. Default.
Kn Modem clock operation: Call-duration or Real-time mode. Displayed
with ATI3 and ATI6 commands.
K0 Display current call-duration if online. Display last
call-duration if offline. Default.
K1 Return actual time at ATI3. Clock is set using
ATI3=HH:MM:SS K1.
&Yn Break handling. This command allows you to send a break to abort
data transfer without disconnecting from the phone link.
&Y0 Destructive, don't send Break.
&Y1 Destructive, expedited (Default).
&Y2 Nondestructive, expedited.
&Y3 Nondestructive, unexpedited; modem sends Break in sequence
with data received from computer or terminal.
NOTE: If the call is under MNP5 data compression, destructive
Breaks cause both modems to reset their data compression tables.
When transmission resumes, the modems build new tables, and the
result is lower than normal throughput.
&ZC=s Write the following command string s to NVRAM. The command string
may be up to 30 characters long; spaces are not counted. This
command can be used so that you can call another modem without
loading your communications software.
After storing a command, you can program the voice/data switch to
execute the stored command string when pressed. The following
example assigns a command string that displays the link diagnostics
screen when you press the voice/data switch.
AT&ZC=I6 <Enter>
The function of the voice/data switch is determined by the setting
of Register S32, as described in Appendix G. Set the voice/data
switch function to execute stored command string by setting Register
S32 to 9 with the following command:
ATS32=9 <Enter>
Note that you can reset the voice/data switch at any time to one of
the other available functions. Additionally, you can overwrite the
stored command string with a new one at any time.
Once you've stored your command string and set Register S32, all
you need to do is press the voice/data switch whenever you want
the command string executed.
&ZC? Display the stored command string.
%T Enables the modem, when off hook, to detect the tone frequencies of
dialing modems. %T is meant primarily for use with network
applications, but may also be integrated into certain software
programs. For example, %T could be used in a security program to
identify incoming tone security codes.
To enable %T, type ATH1 <Enter> to force the modem off hook. Then
type AT%T <Enter>.
To return the modem to Command mode, press any key or drop the
computer's or terminal's DTR signal. The modem responds OK.
Chapter 5--Fax Operations and Call Detection
*************
Compatibility
The Courier modem provides Group III-compatibility when combined with
Class 1 or Class 2.0 fax software. In addition, the modem adheres to
the following standards.
NOTE: The International Telecommunication Union (ITU-T) was formerly
the International Telegraph and Telephone Consultative Committee (CCITT).
TIA/EIA-578 Service Class 1 Asynchronous Facsimile DCE Control
Standard
TIA/EIA-592 Service Class 2.0 Asynchronous Facsimile DCE Control
Standard
ITU-T V.17 14.4K/12K bps
ITU-T V.29 9600/7200 bps
ITU-T V.27 ter 4800/2400 bps
ITU-T V.21 300 bps
********************
Fax Modem Guidelines
Fax operations require facsimile-compatible software that can send or
receive Group III faxes. Follow the instructions in your fax software
manual.
The modem's normal operating mode is Data mode. If your fax software
is typical, it automatically switches the modem to Fax mode when you
run the program, and resets the modem to Data mode when you exit the
program.
If you have a problem, however, and think the modem may be in the
wrong mode, you can use one of the following AT commands to manually
switch the modem:
AT+FCLASS=0 (Switch to Data mode) <Enter>
AT+FCLASS=1 (Switch to Class 1 Fax mode) <Enter>
AT+FCLASS=2.0 (Switch to Class 2.0 Fax mode) <Enter>
If you are not sure whether the modem is in Data or Fax mode, type the
following command.
AT+FCLASS? <Enter>
The modem returns a value of 0 to indicate Data mode, 1 to indicate
Class 1 Fax mode, or 2.0 to indicate Class 2.0 Fax mode.
NOTE: Whenever the fax modem is reset using the ATZ command, by toggling
the DTR signal, or by turning the power off and on, the modem will be set
to Data mode.
*****************************
Fax Mode Flow Control Setting
Many facsimile software products use software flow control when the
modem is in Fax mode. Throughout our documentation, we recommend that
you use hardware flow control for Data mode (factory setting). However,
to allow compatibility with software products that use software flow
control by default, U.S. Robotics fax modems now automatically change
to software flow control when entering Fax mode.
**********
FCC Notice
FCC part 68, rules regarding fax operation, has been amended as follows:
Telephone facsimile machines--identification of the sender of the message:
It shall be unlawful for any person within the United States to use a
computer or other electronic device to send any message via a telephone
facsimile machine unless such a message clearly contains, in a margin at
the top or bottom of each transmitted page or on the first page of the
transmission, the date and time it is sent and an identification of the
business, other entity, or individual sending the message and the
telephone number of the sending machine or of such business, other
entity, or individual. Telephone facsimile machines manufactured on
and after December 20, 1992 must clearly mark such identifying information
on each transmitted page.
********************
Notes to Programmers
Lists of supported Class 1 fax commands and optional Class 2.0 commands
are in Appendix K.
If you want to know more about the supported Class 1 fax commands,
refer to the standard for the Service Class 1 fax protocol.
ANSI/EIA/TIA-578-1990 (EIA-578)
Asynchronous Facsimile DCE Control Standard
November, 1990 Approved: October 22, 1990
For more information on Class 2.0, refer to the standard for the
Service Class 2.0 fax protocol.
ANSI/EIA/TIA-592-1993 (EIA-592)
Asynchronous Facsimile DCE Control Standard
May, 1993
You can obtain copies of these standards by contacting Global
Engineering Documents, at 1-800-854-7179.
**************
Call Detection
Courier High Speed modems support Call Detection, which is a method of
reporting whether an incoming call is Data, Fax Class 1, or Fax Class 2.0.
It is especially useful for Bulletin Board systems, as it automates
recognition of different calls from multiple users.
Call Detection is an optional Service Class 2.0 feature, and is also
implemented by U.S. Robotics for Fax Class 1 applications.
To obtain a copy of the technical specification of U.S. Robotics'
implementation of Call Detection for Fax Class 1, call our BBS at
(708) 982-5092 and download the file CALLSEL.TXT.
For information on implementing Fax Class 2.0 Call Detection, see the
standard listed above. For a list of the optional Fax Class 2.0
commands supported by U.S. Robotics, see Appendix K.
Chapter 6--Queries and Help Screens
*******************
User Inquiries (In)
The Inquiry command has 11 options. The most commonly used options
display the following information:
ATI3 Call duration
ATI4 Current settings
ATI5 NVRAM settings
ATI6 Link diagnostics summary
I0 The modem returns a 4-digit product code. If you have a problem and
call U.S. Robotics' Technical Support Department, you may be asked
for this product code.
I1 The modem performs a checksum of its read-only memory (ROM) and
returns the result to the screen. This function is used only in
factory testing. The modem should always read the same number.
I2 The modem performs a test of its random access memory (RAM) and
returns either the OK (0) or ERROR (4) result code, followed by OK
when the test is completed. You may want to use this command as a
checkpoint if the modem appears to be malfunctioning.
I3 The modem returns the duration of the last call if set to K0. It
displays the actual time if set to K1. See the description of the
Kn command in Chapter 4.
I4 The modem displays its current configuration. Figure 6.1 below
is an example.
Figure 6.1--Sample Result of ATI4 Command
ati4
USRobotics Courier Dual Standard V.34 Fax Settings...
B0 C1 E1 F1 M1 Q0 V1 X1
BAUD=57600 PARITY=N WORDLEN=8
DIAL=PULSE ON HOOK TIMER
&A1 &B0 &C1 &D2 &G0 &H0 &I0 &K1 &L0 &M4 &N0
&P0 &R1 &S0 &T5 &X0 &Y1 %N6
S00=000 S01=000 S02=043 S03=013 S04=010 S05=008 S06=002 S07=060
S08=002 S09=006 S10=007 S11=070 S12=050 S13=000 S14=000 S15=000
S16=000 S17=000 S18=000 S19=000 S20=000 S21=010 S22=017 S23=019
S24=150 S25=005 S26=001 S27=000 S28=008 S29=020 S30=000 S31=000
S32=009 S33=000 S34=000 S35=000 S36=000 S37=000 S38=000 S39=000
S40=000 S41=000 S42=126 S43=200 S44=015 S45=000 S46=000 S47=000
S48=000 S49=000 S50=000 S51=000 S52=000 S53=000 S54=000 S55=000
S56=000 S57=000
LAST DIALED #:
OK
I5 The modem displays the configuration stored in nonvolatile random
access memory (NVRAM), as in the following example. If your
modem connects to a modem that has Dial Security and local access
enabled, you cannot view the stored phone numbers.
Figure 6.2--Sample NVRAM Settings Screen
ati5
USRobotics Courier Dual Standard V.34 Fax NVRAM Settings...
DIAL=PULSE B0 F1 M1 X7
BAUD=57600 PARITY=N WORDLEN=8
&A3 &B1 &G0 &H1 &I0 &K3 &L0 &M4 &N0
&P0 &R2 &S0 &T5 &X0 &Y1 %N6
S00=001 S02=043 S03=013 S04=010 S05=008 S06=002 S07=060 S08=002
S09=006 S10=007 S11=040 S12=050 S13=000 S15=000 S19=000 S21=010
S22=017 S23=019 S24=150 S25=005 S26=001 S27=000 S28=008 S29=020
S31=000 S32=009 S33=000 S34=000 S35=000 S36=000 S37=000 S38=000
S39=000 S40=000 S41=000 S42=126 S43=200 S44=015 S51=000 S53=000
S54=000 S55=000 S56=000 S57=000
STORED PHONE NUMBERS
0: 1:
2: 3:
4: 5:
6: 7:
8: 9:
STORED COMMAND =
OK
I6 During a connection, the modem monitors and stores information
about link operations. When the call is ended, you can request
a diagnostic summary, as in the following example. The duration
of the last call or real time is displayed depending on the Kn
setting.
Figure 6.3--Sample Link Diagnostics Screen (ATI6)
ati6
USRobotics Courier Dual Standard V.34 Fax Link Diagnostics...
Chars sent 0 Chars Received 0
Chars lost 0
Octets sent 0 Octets Received 0
Blocks sent 0 Blocks Received 0
Blocks resent 0
Retrains Requested 0 Retrains Granted 0
Line Reversals 0 Blers 0
Link Timeouts 0 Link Naks 0
Data Compression NONE
Equalization Long
Fallback Disabled
Last Call 00:00:00
Disconnect Reason is Keypress Abort
OK
For calls under data compression, the number of characters sent may be
less than the number of octets sent, due to buffering operations. Line
Reversals only apply to HST-mode operations, when the modems switch the
high and low speed channels. At this time, online fallback is only
reported Enabled in HST-mode.
Most terms used in the display are self-explanatory except for the
following:
Octets:
Compressed data units. If the number of octets is greater than
the number of characters sent, the modems probably used MNP5
compression on an already compressed file, and the result was
expanded data.
Line Reversals:
The number of times HST-mode modems switched the high
and low speed channels.
Blers:
Errors in data and protocol blocks. If there were many block
errors, your receiver may have experienced problems on the line.
Blocks Resent:
These represent blocks the remote modem resent due to
the previous category, Blers.
Link Timeouts:
Protocol detection problems: communications were
severed momentarily, and the modems probably recovered.
This does not indicate the retry timeout.
Link Naks:
Negative acknowledgments (one or more blocks).
Data Compression:
Indicates the type of data compression negotiated
for the call (V42BIS or MNP5) or NONE. A V42BIS
response includes the size of the dictionary and the
maximum string length used, for example, 2048/32.
See Appendix A for more information.
Equalization Long/Short:
Status of S15 bit 0; long if bit 0=0, short
if bit 0=1. Short equalization applies
only to HST modems.
Fallback:
Enabled/Disabled: indicates whether or not the modems
negotiated online fallback during the connection sequence.
Protocol:
indicates the error control protocol negotiated (LAPM,
ST, MNP, NONE) or SYNC for a synchronous call.
Speed:
The last rates at which the receiver/transmitter were operating
before disconnecting.
Disconnect Reason:
Possible reasons the modem hung up are as follows:
A Rootless Tree:
The modem received an invalid V.42 bis (compression)
frame.
Break Timeout:
Incompatible processing of a Break signal occurred.
DISC:
The remote modem sent a V.42 Disconnect frame.
DTR dropped:
The computer or terminal dropped the Data Terminal
Ready signal, terminating the call.
Escape code:
The operator sent the modem the +++ escape code.
Extra Stepup:
The modem received an invalid V.42 bis (compression)
frame.
GSTN (General Switch Telephone Network) Clear Down:
The connection was non-ARQ and DTR was dropped from one side
of the connection, or the DISC frame was corrupted due to
noise.
Illegal Command Code:
The modem received an invalid V.42 bis (compression) frame.
Inactivity timeout:
The modem detected no activity on the line for
the duration specified in Register S19 (default is 0,
timer disabled).
Invalid Codeword:
The modem received an invalid V.42 bis (compression) frame.
Invalid speed:
The modem is set to &N1 or higher, for a fixed
link rate, and the remote modem is not operating at the
same rate.
LD received:
The remote modem sent an MNP error control Link
Disconnect request.
Loop loss disconnect:
The modem detected a loss of current on the
loop connecting it with the telephone company central
office. This usually occurs because the remote modem has
hung up: the central office drops current momentarily
when there is a disconnect at the other end of a call.
Unless Register S38 is set higher than zero, the modem
immediately hangs up at loop loss.
Loss of carrier:
The modem detected loss of the remote modem's
carrier and waited the duration specified in Register
S10 (default is 0.7 seconds).
MNP incompatibility:
The modem is set to &M5 and the remote modem
does not have MNP capability, or there was an MNP
negotiation procedure error.
Retransmit limit:
The modems reached the maximum of twelve attempts
to transfer a data frame without error.
SABME Timeout (Set Asynchronous Balance Mode Extended):
The modems failed this part of V.42 link negotiation.
Unable to Retrain:
After several attempts, disturbances on the phone
line prevented the modems from retraining, and they could
no longer transmit or receive data.
XID Timeout:
The modems failed to negotiate the V.42 Detection
(XID Exchange) phase.
Dial Security Disconnect Reason:
Possible reasons the answering modem may have hung up during a
Dial Security session are as follows:
Security Abort:
The modem hung up because it received an invalid
password three times.
Prompting Not Enabled:
The modem hung up because the originating
modem did not send an autopass password, and prompting wasn't
enabled.
No Prompting in Sync:
The originating modem did not send an autopass
password, and the answering modem cannot prompt for a password
in any synchronous mode.
Non-ARQ Mode:
The modem hung up because the originating modem was
set for error control and the answering modem was set for
non-error control.
Mode Incompatible:
The modem hung up because both modems were not
set to the same error control setting.
No Prompting in Non-ARQ:
Prompting was enabled, but the modem hung
up because the originating modem was set for error control,
and the answering modem was set for non-error control. The
answering modem cannot prompt when it is set for non-error
control.
I7 The modem returns a product configuration. If you have a problem
and call U.S. Robotics' Technical Support staff, you may be asked
to read this screen.
I8 Not used
I9 Not used
I10 View Dial Security Account status. For security administrators
only, unless local security is disabled, S53=0 or S53.2=0.
Figure 6.4--Sample Dial Security Account Status Screen
ati10
USRobotics Courier Dual Standard V.34 Fax
DIAL SECURITY STATUS
DIAL SECURITY ENABLED:[N] LOCAL SECURITY ENABLED:[N]
PROMPTING ENABLED:[N] FORCED AUTOPASS:[N]
LOCAL ACCESS PASSWORD:[NO PSW] AUTOPASS PASSWORD:[NO PSW]
ACCOUNT PSW ACCT/E DIAL/B NEW_# PHONE #
#0 [NO PSW] [N] [N] [N]
#1 [NO PSW] [N] [N] [N]
#2 [NO PSW] [N] [N] [N]
#3 [NO PSW] [N] [N] [N]
#4 [NO PSW] [N] [N] [N]
#5 [NO PSW] [N] [N] [N]
#6 [NO PSW] [N] [N] [N]
#7 [NO PSW] [N] [N] [N]
#8 [NO PSW] [N] [N] [N]
#9 [NO PSW] [N] [N] [N]
OK
I11 Connection report used for debugging purposes. A U.S. Robotics
Technical Support representative may ask you for information
provided on this screen.
**********************
S-Register Query (Sr?)
This command allows you to view the contents of a particular S-Register,
as in the following example that requests the contents of Register S0
("On what ring will the modem answer?"):
ATS0? <Enter>
*************************
Phone Number Query (&Zn?)
At this command, the modem returns the phone number stored in NVRAM at
position n, as in the following example that includes a sample modem
response:
AT&Z3? <Enter>5551234
******************************
Last-Dialed Number Query (DL?)
At this command the modem displays the number stored in the last-dialed
number buffer:
ATDL? <Enter>
**********************************
Stored Command String Query (&ZC?)
At this command the modem displays the command string stored in NVRAM with
the &ZC=s command:
AT&ZC? <Enter>
************
HELP Screens
Courier modems provide five Help screens: summaries of the basic AT
command set, extended ampersand (&) command set, Dial command options,
S-Register functions, and percent (%) command set.
NOTE: The Help screens are not available when the modem makes a
connection in synchronous mode: &M1, &M6, or &M7.
Stop/Restart Display
The following command stops the display. Hold down the Control key and
type "S":
<Ctrl>-S
To restart the display, use the same command or press any key.
Cancel Display
Either of the following commands cancels the display.
<Ctrl>-C
<Ctrl>-K
*********************
Basic Command Set ($)
At AT$, the Courier displays a screen that shows a partial summary of the
command set. A second screen, activated by pressing any key, shows the
remaining commands. The first screen is shown in Figure 6.5.
Figure 6.5--Sample Basic Commands HELP Screen
at$
HELP, Command Quick Reference (CTRL-S to Stop, CTRL-C to Cancel)
&$ HELP, Ampersand Commands Kn n=0 Call Duration Mode
%$ HELP, Percent Commands n=1 Real Time Clock Mode
A/ Repeat Last Command Mn n=0 Speaker Off
A> Continuously Repeat Command n=1 Speaker On Until CD
AT Command Mode Prefix n=2 Speaker Always On
A Answer Call n=3 Speaker Off During Dial
Bn n=0 V.32 originate mode On n=0 Return Online
n=1 HST originate mode n=1 Return Online & Retrain
Cn n=0 Transmitter Off n=2 Return Online & Speed Shift
n=1 Transmitter On P Pulse Dial
Dn Dial a Telephone Number Qn n=0 Result Codes Sent
n=0..9#*TPR,;"W@!()- n=1 Quiet (No Result Codes)
DL Dial Last Phone Number n=2 Verbose/Quiet On Answer
DSn Dial Stored Phone Number Sr=n Sets Register "r" to "n"
D$ HELP, Dial Commands Sr? Query Register "r"
En n=0 No Command Echo S$ HELP, S Registers
n=1 Echo Command Chars T Tone Dial
Fn n=0 Online Echo Vn n=0 Numeric Responses
n=1 No Online Echo n=1 Verbal Responses
Strike a key when ready . .
*************************
Extended Command Set (&$)
At AT&$, the Courier displays a screen that shows a partial summary of the
extended ampersand command set. A second screen, activated by pressing
any key, shows the remaining command set. The first screen is shown in
Figure 6.6.
Figure 6.6--Sample Ampersand Commands HELP Screen
at&$
HELP, Ampersand Commands (CTRL-S to Stop, CTRL-C to Cancel)
&An n=0 Disable /ARQ Result Codes &Nn n=0 Highest Link Speed
n=1 Enable /ARQ Result Codes n=1 300 bps
n=2 Enable /Modulation Codes n=2 1200 bps
n=3 Enable /Extra Result Codes n=3 2400 bps
&Bn n=0 Floating DTE Speed n=4 4800 bps
n=1 Fixed DTE Speed n=5 7200 bps
n=2 DTE Speed Fixed When ARQ n=6 9600 bps
&Cn n=0 CD Always On n=7 12000 bps
n=1 Modem Controls CD n=8 14400 bps
&Dn n=0 Ignore DTR n=9 16800 bps
n=1 On-Line Command Mode n=10 19200 bps
n=2 DTE Controls DTR &Pn n=0 N.American Pulse Dial
&Fn n=0 Load Factory Configuration n=1 UK Pulse Dial
n=1 Hardware Flow Control Cnfg. &Rn n=0 CTS Follows RTS
n=2 Software Flow Control Cnfg. n=1 Ignore RTS
n=3 HST/Cellular w/ HW FC Cnfg. n=2 RX to DTE/RTS high
&Gn n=0 No Guard Tone &Sn n=0 DSR Always On
n=1 550 Hz Guard Tone n=1 Modem Controls DSR
n=2 1800 Hz Guard Tone n=2 Pulse DSR, CTS=CD
Strike any key when ready . . .
*************
Dialing (D$)
At ATD$, the Courier displays this Dial command summary:
Figure 6.7--Sample Dial Command HELP Screen
atd$
HELP, Dial Commands (CTRL-S to Stop, CTRL-C to Cancel)
0-9 Digits to Dial
* Auxiliary Tone Dial Digit
# Auxiliary Tone Dial Digit
T Tone Dialing
P Pulse Dialing
R Call an Originate Only Modem
, Pause (Wait for S8 Time)
; Remain in Command Mode After Dialing
" Used to Dial Alpha Phone #'s
W Wait for 2nd Dial Tone (X3-X7)
@ Wait for an Answer (X3-X7)
! Flash Switch Hook
OK
*************************
S-Register Functions (S$)
At ATS$, the Courier displays a screen that shows a partial summary of
the S-Register functions. More screens, activated by pressing any key,
show the remaining registers. The first screen is as follows.
Figure 6.8--Sample S-Register HELP Screen
ats$
HELP, S Register Functions (CTRL-S to Stop, CTRL-C to Cancel)
S0 Ring to Answer On S33 Reserved
S1 Counts # of Rings S34 Bit Mapped
S2 Escape Code Char 1 = Disable V32bis
S3 Carriage Return Char 2 = Disable Enhanced V32 mode
S4 Line Feed Char 4 = Disable Quick V32 retrain
S5 Backspace Char 8 = Enable V23 Fallback
S6 Wait Time/Dial Tone (sec) 16 = Change MR to DSR
S7 Wait Time/Carrier (sec) 32 = Enable MI/MIC
S8 Comma Time (sec) 64 = Disable RA Busy Msg
S9 Carrier Detect Time (1/10sec) 128 = Disable Terbo
S10 Carrier Loss Time (1/10sec) S35 Reserved
S11 Dial Tone Spacing (msec) S36 Reserved
S12 Escape Code Time (1/50sec) S37 Reserved
S13 Bit Mapped S38 Disconnect Wait Time (sec)
1 = Reset On DTR Loss S39 Reserved
2 = Do Originate in Auto Answer S40 Reserved
4 = No Pause Before Result Codes S41 # of Allowed Login Attempts
8 = Do DS0 On DTR S42 Remote Escape Code Char
16 = Do DS0 On Reset S43 Remote Escape Code Time (1/50sec)
Strike a key when ready . . .
*********************
Percent Commands (%$)
At AT%$, the Courier displays a screen that shows a partial summary of
the percent command functions. A second screen, activated by pressing
any key, shows the remaining registers. The first screen is as follows.
Figure 6.9--Sample Percent HELP Screen
at%$
HELP, Percent Commands (CTRL-S to Stop, CTRL-C to Cancel)
%An= Security Account Information %Fn Remote DTE Data Format
Command Structure n=0 8, No parity
%An= PW,ACCT E,DIAL B,NEW#,PH# n=1 7, Mark parity
n = (0-9) n=2 7, Odd parity
PW = Password n=3 7, Even parity
ACCT E = Account Enable %L=PWn Security Local Access Psw
DIAL B = Dial Back Enable PWn = (0-9)
NEW# = New Dial Back # %Nn V.25bis Synchronous Clock Rate
PH# = Dial Back Phone # n=0 RESERVED
%Bn Remote DTE Data Rate n=1 RESERVED
n=0 110 bps n=2 1200 bps
n=1 300 bps n=3 2400 bps
n=2 600 bps n=4 4800 bps
n=3 1200 bps n=5 7200 bps
n=4 2400 bps n=6 9600 bps
n=5 4800 bps n=7 12000 bps
n=6 9600 bps n=8 14400 bps
n=7 19200 bps n=9 16800 bps
n=8 38400 bps n=10 19200 bps
Strike a key when ready . . .
Appendix A--Link Negotiation (Handshaking) and Error Control
This appendix includes information on how U.S. Robotics modems
negotiate with remote modems for the rate and other characteristics
of each connection. In addition, you'll find information on error
control and, especially useful, some statistics and guidelines on
using the modem for the best throughput.
Some of the following text includes the term ARQ, which means Automatic
Repeat Request. ARQ is a method used in many error control protocols to
ensure that any data that has been corrupted in transit is retransmitted.
We use the term in our documentation to designate a connection under
error control.
NOTE: High speed calls are highly vulnerable to errors unless the
data is protected by error control. The V. protocol operations
described below take place even if one of the modems is not set for
error control, thereby prohibiting error control for the call.
If your modem connects with a modem at high speed but without error
control, and if you are not using an error control protocol for
your call, you may lose data.
Dual Standard modems in HST mode, in contrast, are unable to connect
with other HST modems at higher than 2400 bps, unless error control
is negotiated for the call.
****************
V.34 Handshaking
The Courier defaults to V.34 and tries for the highest possible speed
when it attempts to connect with another modem, 28.8K bps. The entire
V.FC range comprises 28.8K, 26.4K, 24K, 21.6K, 19.2K, 16.8K, 14.4K,
9600, 7200, 4800, and 2400 bps. If the remote modem is not V.34
capable, a connection is made using the highest compatible modulation
scheme (V.FC, V.32 terbo, V.32 bis, and so on, down to as low as Bell
103, or 300 bps).
If the remote modem has V.34 capability, the two modems use a line
probing technique to determine the highest speed possible under
current line conditions, and complete the connection. If the remote
modem does not have V.34 capability, a calling Courier modem listens
to the other modem's answer tones to identify what standard rate the
remote modem is operating at, and adjusts to that rate. An answering
Courier modem sends out a series of answer tone signals until both modems
can negotiate the best connection rate.
********************************
V. Fast Class (V.FC) Handshaking
The Courier defaults to V.Fast Class and tries for the highest
possible speed when it attempts to connect with another modem,
28.8K bps. The entire V.FC range comprises 28.8K, 26.4K, 24K,
21.6K, 19.2K, 16.8K, and 14.4K bps. If the remote modem is not
V.FC capable, a connection is made using the highest compatible
modulation scheme (V.32 terbo, V.32 bis, and so on, down to as
low as Bell 103, or 300 bps).
If the remote modem has V.FC capability, the two modems use a line
probing technique to determine the highest speed possible under
current line conditions, and complete the connection. If the
remote modem does not have V.FC capability, a calling Courier modem
listens to the other modem's answer tones to identify what standard
rate the remote modem is operating at, and adjusts to that rate. An
answering Courier modem sends out a series of answer tone signals
until both modems can negotiate the best connection rate.
****************************************************
U.S. Robotics V.32 terbo to U.S. Robotics V.32 terbo
On these connections, Couriers have two features that result in
outstanding performance: Quick Connect and Adaptive Speed Leveling
(ASL).
Quick Connect allows the modems to connect in approximately 7 seconds,
a far shorter time than normal with most modems.
ASL (described below in Other V.Protocol Operations) is used by U.S.
Robotics modems operating in V.32 terbo and V.32 bis modes.
****************************
Other V. Protocol Operations
Earlier, lower-speed V. protocols do not employ line probing. Instead,
they use predefined answer tones to specify, or identify, speed
capabilities. These protocols define the following maximum speeds.
* V.32 terbo: 19.2K bps, with an additional Courier-to-Courier
speed of 21.6K bps.
* V.32 bis: 14.4K bps.
* V.32: 9600 bps.
ASL (used in V.32 terbo and V.32 bis modes) is a strategy that allows
the modems' receivers and transmitters to act independently of each
other. We have always featured a fallback/fall forward feature with
error-correcting modems that allows them to slow down if there are
problems with the phone line, in order to avoid data errors, and then
speed up again. But the independence of the receiving and transmitting
channels means that one channel or the other may slow down and then speed
up, without affecting the data flow on the other. The result is more
efficient line operation.
WARNING: Answering V.32 terbo modems shift their serial port rate up
to 38.4K (for 21.6K connections) if the calling V.32 terbo modem dials
in at 21.6K. The answering V.32 terbo modem then sends data to its
computer at 38.4K bps. V.32 bis modems shift their serial port rate
to 19.2K bps in order to make 14.4K bps connections. If your ocomputer
or terminal does not support these higher serial port rates, you need
to disable V.32 terbo and/or V.32 bis. See Appendix B, Register S34.
NOTE: While many modems on the market now use the more efficient
speeds, there may be a problem in answering older, "dumb" V.32
modems at 9600 bps. Register S28 is used to modify the duration
of the extra tones used in V.32 negotiations, in the rare instance
that this may be necessary. See S-Registers, in Appendix B.
*************************
Dual Standard Handshaking
We recommend that Dual Standard modems be set to retain the default
B0 and &N0 settings. This allows them to connect with V. protocol
modems and HST modems in both Originate and Answer modes at a variety
of speeds.
An originating Dual Standard modem set to B1 sends out a Bell answer
tone, which is the prevalent standard in the U.S. and Canada for
connections at 2400 bps and lower. At higher speeds, the Dual
Standard also recognizes the ITU answer tones necessary for
connecting with V. protocol modems, and adjusts to the answering
modem.
However, in Answer mode, a Dual Standard modem sending out the Bell
answer tone (B1) won't be recognized by V. protocol modems. The
calling V. protocol modem, instead, will wait until it detects a
tone it recognizes, the V.22 bis tone used at 2400 bps. If you
wish to have your Dual Standard connect with V. protocol modems at
high speeds, make sure it is set to B0 for the ITU answer tones.
It will also connect with HST modems at speeds up to 16.8K bps.
****************************
Error Control and Throughput
Error control is available for calls at 1200 bps and above. It can be
disabled, although high speed calls (above 2400 bps) should always
be under error control. The operations defined in an error control
protocol include the following:
* Establishment of compatibility
* Data frame formatting
* Error detection through Cyclic Redundancy Checking (CRC)
* Retransmission of corrupt data frames
The Courier is set at the factory to &M4, causing it to try for an error
control connection and, if that isn't possible, to proceed with the call
in Normal mode. The modem first tries for a V.42 connection, then an
MNP connection. The following information is based on the Courier's
setting of &M4.
****************
V.42 Handshaking
This international standard includes a two-stage handshaking process:
* A Detection phase that is based on an exchange of predefined characters.
* LAPM (Link Access Procedures for Modems) Negotiation. In this phase,
the modems identify their capabilities concerning maximum data block
size and the number of outstanding data blocks allowed before an
acknowledgment is required.
***************
MNP Handshaking
This protocol is supported by the ITU-T V.42 Recommendation. It was
originally developed by Microcom, Inc. and is now in the public domain.
MNP is based on special protocol frames. If the remote modem doesn't
recognize an MNP Link Request, error control isn't possible. (In HST
asymmetrical mode, U.S. Robotics modems use a proprietary scheme
similar to MNP.)
****************
Data Compression
If the modems successfully establish a V.42 connection, they also negotiate
for V.42 bis data compression. If they successfully establish an MNP
connection, they negotiate for MNP5 data compression. The type of
compression for a call, if any, is reported in the ATI6 display, and
in the CONNECT message if the modem is set to &A3.
Modems using V.42 bis compression negotiate the following options and
report them in the ATI6 display.
* Dictionary size, that is, the amount of memory available for compression
table entries. (Entries are codes devised for redundant data. The
data is packed into shorter data units, called code words, and unpacked
by the receiving modem.)
Possible sizes are as follows:
Bits Entries
9 512
10 1024
11 2048
U.S. Robotics modems use 11-bit, or 2048-entry dictionary, but drop down
if the remote modem uses a 9- or 10- bit dictionary. The size of the
dictionary for a call is reported in the ATI6 display.
* Maximum string length of each entry. As the dictionary fills, the
modem deletes the oldest unused strings.
V.42 bis compression is more efficient than MNP5 compression in part
because it dynamically deletes entries that are no longer used. In
addition, it works better with files that are already compressed.
These include .ZIP files downloaded from many Bulletin Boards and
8-bit binary files, which seem to the modem to be compressed.
MNP5 compression should not be used with such files because it adds data
to them, which lessens throughput. (The additional data is stripped when
the file is decompressed by the remote modem.) When transferring
such files, it's best to set the modem to &K3: this allows V.42 bis
compression to work dynamically with the compressed data, but disables
MNP5.
************
Flow Control
Flow control of data from the computer is required under error control
for two reasons:
1. The transmitting modem buffers a copy of each frame it transmits to
the remote end until it is acknowledged by the receiving modem.
2. If errors are encountered, retransmission activity can cause a
steady stream of data from the computer to overflow the buffer.
*********************
Throughput Guidelines
The following guidelines should help to make the most of the modem's
advanced performance features. In many instances, experimentation
and experience will indicate what works best for your applications.
1. Optimal throughput is attained under the following conditions:
* The communications software allows fixing the serial port rate
higher than the connection rate, by setting the software to
115.2K, 57.6K, or 38.4K bps and setting the modem to &B1.
If the software automatically switches serial port rates to follow
the connection rate, the modem's serial port rate must be also set
to follow the connection rate for each call, &B0, and throughput
will be limited.
Installations with specialized software may want to enable a fixed
serial port rate for ARQ calls and a variable serial port rate for
non-ARQ calls. See the &B2 command in Chapter 4.
* The call is under data compression.
* The data is comprised of text files rather than binary files such
as .EXE or .COM files. See the table at the end of this appendix.
2. MNP5 compression is disabled for files that are already compressed,
and 8-bit binary files that appear to the modem to be already compressed.
MNP5 is disabled by setting the modem to &K3.
3. The file transfer is not slowed down by a file-transfer protocol.
Many non-text files require a file transfer protocol, but the results
vary. For example, certain public domain file transfer protocols
have the following effects:
Kermit Newer versions support packets up to 9K and a sliding window
design to eliminate turn-around delay. With earlier versions,
however, throughput may be severely reduced due to short block
lengths (possibly under 128 bytes) and acknowledgment
turnaround time.
Xmodem Throughput may be reduced if your version uses short block
lengths (128 bytes). Some versions use larger blocks
(1K blocks). Throughput is also reduced by overhead (error
control protocol information).
Ymodem There is an improvement over Xmodem, due to larger block
lengths (1K bytes), but throughput is still reduced by the
protocol's error control overhead.
The above protocols further reduce throughput when an error control
connection is established. The accuracy of the data is checked both
by the file transfer protocol and the modem. To avoid redundancy,
use the above protocols only for non-ARQ connections, and only at
speeds of 2400 bps and below.
For the best throughput, but on error-controlled connections only and
with hardware flow control, we recommend the most current version of
Zmodem. Overhead is minimal with this protocol, with throughput
almost equal to that obtained with no file-transfer protocol. Zmodem
should also be used for non-ARQ connections. Leave the modem at its
&M4 and &K1 settings for both error control and data compression.
Ymodem-G is another good choice, but never without both the local
and remote modems using error control: if Ymodem-G detects an error,
it aborts the transfer. Do not use either protocol with software flow
control (XON/XOFF signaling).
******************
Typical Throughput
The maximum connection rate between two V.34 modems is 28.8K bps.
Ocassionally, connections occur at 26.4K, 24K, and 21.6K bps because
line quality differs from location to location Line conditions and
data rate affect throughput. Also remember, your serial port rate
must match or exceed your connection rate. If you set your serial port
rate at 19.2K bps, the V.34 modem will only connect at or below 19.2K bps.
The tables below indicate the typical throughput, in characters per
second (cps), that can be expected under the following conditions.
* Connection (link) rates of 14.4K, 21.6K, and 28.8K bps, respectively
* Serial port rates set at 57.6K bps for the 14.4K bps connection and
115.2K bps for the 21.6K and 28.8K bps connections
* Modem set to &B1 (fixed serial port rate)
* V.42 bis compression negotiated for the call, and the default size
11-bit, 2048-entry dictionary
* Straight data (not already compressed, no file-transfer protocol)
* Transmission from a fast (486) computer
NOTE: .ZIP files that are already compressed or files that appear to
the modem to be compressed yield lower throughput. We recommend
setting the modem to &K3 when transferring these files, to allow V.42
bis but disable MNP5.
14.4K bps
File Type Typical throughput (cps)
Text file 3400
.ZIP files 1600
Database files 4600
Graphic files 2900
21.6.4K bps
File Type Typical throughput (cps)
Text file 5100
.ZIP files 2400
Database files 7200
Graphic files 4300
28.8K bps
File Type Typical throughput (cps)
Text file 6800
.ZIP files 3200
Database files 9600
Graphic files 5800
Appendix B--Summaries and Tables
CONTENTS
The RS-232 Interface, with Pin Definitions
Front Panel Indicators
DIP Switch Summary
Default Settings
S-Register Summary
ASCII Chart
********************
THE RS-232 INTERFACE
***********
Description
The RS-232 interface is a standard developed by the Electronic
Industries Association (EIA). It defines the signals and voltages
used when data is exchanged between a computer or terminal and a
modem or serial printer. Data is transmitted between the devices
via a cable with 25-pin, 9-pin, 8-pin or custom-built connectors.
The modem takes a DB-25P (25-pin plug, or male) connector at one
end of the cable. Computer equipment varies, however. Check the
serial port at the rear of your machine, which may be labeled serial,
comm port, or some other term (e.g., RS-232). If there are no labels,
review your machine documentation to find out which is the serial port.
(There may be more than one.) Don't use a port marked parallel,
printer or aux.
The physical serial port on the computer or terminal will be either a
socket (female) or plug (male) that typically accommodates 25 or 9
pins. For example, the port on the IBM PC, PC/XT and most compatibles
requires a DB-25S (socket) connector, while the port on the IBM PC/AT
and some compatibles requires a DB-9S connector. Apple computers
require a DB-25P, DB-9P or, more typically, an 8-pin round plug connector.
Check your computer documentation or with your computer dealer.
***************
Pin Assignments
The entire standard covers many more functions than are used in most
data communications applications. Pin assignments are factory set
in the Courier to match the standard DB-25 assignments in the
following table. DB-9 connectors for AT-compatible computers
should be wired at the computer end of the cable as shown in the
DB-9 column. If you're using an Apple computer, we strongly recommend
that you purchase a Hardware Handshaking cable to get the highest
possible reliability performance.
Table B.1--RS-232 Interface Pin Definitions
Signal Flow
Computer
DB-25 DB-9 Circuit Function to Modem
1 _ AA Chassis Ground both directions
2 3 BA Transmitted Data to modem
3 2 BB Received Data to computer
4 7 CA Request to Send to modem
5 8 CB Clear to Send to computer
6 6 CC Data Set Ready to computer
7 5 AB Signal Ground both directions
8 1 CF Carrier Detect to computer
12 _ SCF Speed Indicate to computer
15 _ DB Synchronous TX* Timing to computer
17 _ DD Synchronous RX* Timing to computer
20 4 CD Data Terminal Ready to modem
22 9 CE Ring Indicate to computer
24 _ DA Synchronous TX* Timing to modem
* Indicates Transmitter (TX) or Receiver (RX)
*******************
Minimum Requirements
Some computer/terminal equipment supports only a few of the RS-232 signal
functions set in the Courier. The minimum required for the modem to
operate are as follows:
Asynchronous Calls
DB-25 DB-9
Pin Pin Function
2 3 Transmitted Data
3 2 Received Data
7 5 Signal Ground
20 4 Data Terminal Ready*
* Required only if you have the Data Terminal Ready Operations
switch OFF (DIP switch 1 OFF).
Synchronous Calls
You will need all of the above functions as well as pin 15 for
Transmitter timing signals, and pin 17 for Receiver timing signals.
You may need pin 24, which is assigned the external timing source,
rather than the internal (modem) source assigned to pin 15. See
Appendix F for more detailed information.
Additional Flow Control Functions
If your computer and software support Clear to Send and you wish to use
Transmit Data hardware flow control (&H1), Pin 5 (DB-25) or Pin 8 (DB-9)
is required.
If your computer and software support Request to Send and you wish
to use Received Data hardware flow control (&R2), Pin 4 (DB-25) or
Pin 7 (DB-9) is required.
***********************************
For 38.4K or Higher Serial Port Rate
Your terminal or computer and software must support the 115.2K, 57.6K, or
38.4K bps rate. Make sure the RS-232 cable is shielded. Cables are
normally six feet long, but longer lengths are possible. If you
encounter problems with signal degradation, try a shorter cable.
If you decide to build your own cable, use a low-capacitance cable.
To further minimize the capacitance, connect only those functions
(pins) that your application requires.
FRONT PANEL INDICATORS
Symbol Meaning Status
HS High Speed All calls above 2400 bps: ON during call
progress, after completion of dialing; OFF
during HST-mode link negotiations at 2400
bps, then ON during connection. Remains
ON after disconnect until next call is
originated or answered, or the modem
is reset.
AA Auto Answer/ Answer mode only: ON when your modem is
Answer in Auto Answer mode, and when answering a
call; in HST-mode, goes OFF if the channel
is reversed and your answering modem
transmits at 450 or 300 bps. Also goes
OFF when the modem originates a call.
Flashes ON for incoming ring detect.
CD Carrier Detect ON if DIP switch 6 is OFF (factory
setting) and the Courier receives a valid
data signal (carrier) from a remote modem,
indicating that data transmission is
possible. Also ON when the CD override
is on, DIP switch 6 ON.
OH Off Hook ON when the Courier takes control of the
phone line to establish a data link.
RD Received Data Flashes when the modem sends result codes
or passes received data bits to the
computer or terminal.
SD Send Data Flashes when the computer or terminal
sends a data bit to the Courier.
TR Data Terminal ON if DIP switch 1 is OFF (factory
Ready (setting) and the modem receives a DTR
signal from the computer or terminal.
Also ON when the DTR override is on, DIP
switch 1 ON.
MR Modem Ready/ ON when the Courier is powered on.
Test Mode Flashes when the modems retrain, including
online fallback, or while the modem is in
Test mode.
RS Request to ON if your terminal or software supports
Send RTS and sends the RTS signal. OFF if the
Courier is set to &R2 (Received Data
hardware flow control) and the computer or
terminal lowers RTS.
CS Clear to Send ON until the modem lowers CTS when
Transmit Data hardware flow control is
enabled (&H1, &H3). Always ON during
synchronous connections.
SYN Synchronous ON when the modem is set to &M1, &M6,
Mode &M7 and enters synchronous mode. Flashes
when Dial Security is in operation.
ARQ/ Error Control/ Data Mode: Automatic Repeat Request. ON
FAX Fax Operations when the Courier is set to
&M4 or &M5 and successfully connects with
another modem under error control.
Flashes randomly when the Courier
retransmits data to the remote modem.
Fax Mode: Flashes steadily to indicate
fax mode.
******************
DIP SWITCH SUMMARY
The DIP switches, located at the rear of the modem, are for adapting the
modem to your equipment and personal requirements. If necessary, review
your software documentation.
Some users are able to move a single switch with a finger tip. If this
doesn't work for you, use a toothpick or other small instrument. Do not
use a lead pencil.
OPERATIONS
The DIP switch settings are power-on defaults, read by the Courier when
it is turned on. If changed when the modem is on, switches 1-7, and 9
require the ATZ (software reset) command to initiate the new settings.
If you've set switch 8 OFF to disable command recognition, and want to
return the modem to Smart mode so that it responds to commands, just
reset switch 8 to ON.
When you issue the ATZ command, the modem reads its DIP switch settings
and resets either to its defaults (DIP switch 10 OFF) or factory settings
(DIP switch 10 ON).
Factory
Switch Setting Function
1 OFF Data Terminal Ready Operations
OFF Normal DTR operations: computer must
provide DTR signal for modem to accept
commands; dropping DTR terminates a call
ON DTR always ON (Override)
2 OFF Verbal/Numeric Result Codes
OFF Verbal (word) results
ON Numeric results
3 ON Result Code Display
OFF Results suppressed
ON Results enabled
4 OFF Command Mode Local Echo
OFF Keyboard commands displayed
ON Echo suppressed
5 ON Auto Answer
OFF Modem answers on first ring
ON Auto answer disabled
6 OFF Carrier Detect Operations
OFF Courier sends CD signal when it connects
with another modem, drops CD on disconnect
ON CD always ON (Override)
7 OFF Auxiliary, DIP Switch 3 ON
OFF Result codes in Originate and Answer mode
ON Result codes in Answer mode disabled
8 ON AT Command Set Recognition
OFF Command recognition disabled (Dumb mode)
ON Recognition enabled (Smart mode)
9 OFF Escape Code (+++) Response
OFF Modem hangs up, returns to Command mode,
sends NO CARRIER result
ON Modem maintains connection, returns to
Command mode, sends OK result
10 OFF Power-on and ATZ Reset Software Defaults
OFF Load from nonvolatile memory (NVRAM)
ON Load factory settings from read only
memory (ROM)
****************
DEFAULT SETTINGS
USER-PROGRAMMABLE DEFAULTS
You can create your own default configuration and store it in nonvolatile
random access memory (NVRAM) using the &W command described in Chapter 4.
As long as DIP switch 10 is OFF when you power on the modem, your defaults
are loaded into the modem's random access memory (RAM). To view your NVRAM
settings at any time, use the ATI5 command.
Tables on the next several pages list the options you can store in NVRAM,
including S-Register settings. If DIP switch 10 is ON at power-on, the
factory template 0 settings are loaded instead. The modem has four factory
setting templates (&F0-F3). By default, the first time the modem is turned
on, the modem loads the settings stored in NVRAM, which are the same as
the settings in factory template 1 (&F1).
The following command example substitutes several user-defined defaults
for factory settings. The modem also stores the rate, word length and
parity it detects from the AT command prefix.
AT X1 &B0 &M5 &H0 M3 &W <Enter>
The modem is shipped with DIP switch 10 OFF, so when it is powered on it
loads the settings from NVRAM. Until these settings are changed, they are
the same as the settings permanently stored in factory settings template 1
(&F1). You can alter any of these settings, create your own power-on
defaults, and then save them with the &W command. See Chapter 4.
Table B.3--&F1 Hardware Flow Control Default Template
NVRAM Options Setting Description
Handshake option B0 ITU-T answer sequence
Error control/sync &M4 Normal/error control
Data compression &K1 Enabled
Transmit data hardware &H1 Hardware flow control
Rec'd data hardware flow control &R2 Enabled
Rec'd data software flow control &I0 Disabled
Serial port rate select &B1 Serial port rate fixed higher
than connect rate
Link rate select &N0 Variable
Result code subset X7 Extended. Includes all codes
except VOICE
Protocol response codes &A3 Full protocol codes
Tone/Pulse dialing P Pulse dial
Online local echo F1 Disabled
Speaker control M1 ON during dial through connect
Remote Digital Loopback (RDL) &T5 Deny RDL
Normal/Leased/Cellular line &L0 Normal phone line
Data Set Ready operations &S0 Override enabled
Break handling &Y1 Clear buffer, send immediately
Stored telephone number &Z0-9=0 Blank
Pulse dial make/break ratio &P0 U.S./Canada
Guard tone &G0 U.S./Canada
Word length* 8
Parity* 0 None
DTE rate* (Kbps) 19.2 _
* Detected by the modem from the AT prefix of the &W command that
writes your defaults to NVRAM. Set your software to the desired word
length, parity, and serial port rate defaults before sending the modem
the AT . . . &W string.
Table B.4--&F2 Software Flow Control Template
NVRAM Options Setting Description
Handshake option B0 ITU-T answer sequence
Normal/error control/sync &M4 Normal/error control
Data compression &K1 Enabled
Transmit data flow control &H2 Software flow control
Rec'd data hardware flow control &R1 Disabled
Rec'd data software flow control &I2 Enabled
Serial port rate select &B1 Serial port rate fixed higher
than connect rate
Link rate select &N0 Variable
Result code subset X7 Extended. Includes all codes
except VOICE
Protocol response codes &A3 Full protocol codes
Tone/Pulse dialing P Pulse dial
Online local echo F1 Disabled
Speaker control M1 ON during dial through connect
Remote Digital Loopback (RDL) &T5 Deny RDL
Normal/Leased/Cellular line &L0 Normal phone line
Data Set Ready operations &S0 Override enabled
Break handling &Y1 Clear buffer, send immediately
Stored telephone number &Z0-9=0 Blank
Pulse dial make/break ratio &P0 U.S./Canada
Guard tone &G0 U.S./Canada
Word length* 8
Parity* 0 None
DTE rate* (Kbps) 19.2 _
* Detected by the modem from the AT prefix of the &W command that writes
your defaults to NVRAM. Set your software to the desired word length,
parity, and serial port rate defaults before sending the modem the
AT . . . &W string.
Table B.5--&F3 HST Cellular Template
NVRAM Options Setting Description
Handshake option B1 HST-mode/Bell answer tone
Normal/error control/sync &M4 Normal/error control
Data compression &K1 Enabled
Transmit data flow control &H1 Hardware flow control
Rec'd data hardware flow control &R2 Enabled
Rec'd data software flow control &I0 Disabled
Serial port rate select &B1 Serial port rate fixed higher
than connect rate
Link rate select &N0 Variable
Result code subset X7 Extended. Includes all codes
except VOICE.
Protocol response codes &A3 Full protocol codes
Tone/Pulse dialing P Pulse dial
Online local echo F1 Disabled
Speaker control M1 ON during dial through connect
Remote Digital Loopback (RDL) &T5 Deny RDL
Normal/Leased/Cellular line &L2 HST Cellular
Carrier loss wait time S10=30 Waits 3 seconds before hanging up
Data Set Ready override &S0 Enabled
Break handling &Y1 Clear buffer, send immediately
Stored telephone number &Z0-9=0 Blank
Pulse dial make/break ratio &P0 U.S./Canada
Guard tone &G0 U.S./Canada
Word length* 8
Parity* 0 None
DTE rate* (Kbps) 19.2 _
* Detected by the modem from the AT prefix of the &W command that writes
your defaults to NVRAM. Set your software to the desired word length,
parity, and serial port rate defaults before sending the modem the
AT . . . &W string.
If DIP switch 10 is ON when the modem is powered on, or you load factory
template 0 (&F0), the following settings take effect.
Table B.6--&F0 No Flow Control Low Performance Template
NVRAM Options Setting Description
Handshake option B0 ITU-T answer sequence
Normal/error control/sync &M4 Normal/error control
Data compression &K1 Enabled
Transmit data flow control &H0 Disabled
Rec'd data hardware flow control &R1 Disabled
Rec'd data software flow control &I0 Disabled
Serial port rate select &B0 Detect from AT command: variable
rate
Link rate select &N0 Variable
Result code subset X1 Basic
Error-control response codes &A1 Enabled
Tone/Pulse dialing P Pulse dial
Online local echo F1 Disabled
Speaker control M1 ON during dial through connect
Remote Digital Loopback (RDL) &T5 Deny RDL
Normal/Leased/Cellular line &L0 Normal phone line
Data Set Ready operations &S0 Override enabled
Break handling &Y1 Clear buffer, send immediately
Stored telephone number &Z0-9=0 Blank
Pulse dial make/break ratio &P0 U.S./Canada
Guard tone &G0 U.S./Canada
Word length* 7
Parity* 1 Even
DTE rate* (bps) 9600
* Detected by the modem from the AT prefix of the &W command that writes
your defaults to NVRAM. Set your software to the desired word length,
parity, and serial port rate defaults before sending the modem the
AT . . . &W string.
Table B.7--NVRAM Options
Factory
NVRAM S-Register Options Setting
S0 Auto Answer 1
S2 Escape code character 43
S3 Carriage Return character 13
S4 Line Feed character 10
S5 Backspace character 8
S6 Dial wait-time, sec. 2
S7 Carrier wait-time, sec. 60
S8 Dial pause, sec. 2
S9 Carrier Detect time, 1/10th sec. 6
S10 Carrier loss wait-time, 1/10th sec. 7
S11 Tone duration, spacing, msec. 70
S12 Escape code guard time, 1/50th sec. 50
S13 Bit-mapped functions* 0
S15 Bit-mapped functions* 0
S19 Inactivity/hang up timer 0
S21 Break length, 1/100th msec. 10
S22 XON character 17
S23 XOFF character 19
S24 Pulsed DSR duration, 2/100th sec. 150
S26 RTS/CTS delay time, 1/100th sec. 1
S27 Bit-mapped functions* 0
S28 V.32 handshake time, 1/10th sec. 8
S29 V.21 handshake time, 1/10th sec. 20
S32 Voice/Data Switch Options 9
S33 Bit-mapped functions* 0
S34 Bit-mapped functions* 0
S38 Disconnect wait time, sec. 0
S41 Allowable remote login attempts 0
S42 Remote Access ASCII character 126
S43 Remote guard time, 1/50th sec. 200
S44 Re-establish leased-line connect, sec. 15
S51 Bit-mapped functions* 0
S53 Bit-mapped functions* 0
S54 Bit-mapped functions* 0
S55 Bit-mapped functions* 0
S56 Bit-mapped functions* 0
S57 Bit-mapped functions* 0
* Bit-mapped registers have up to eight functions. See
descriptions later in this appendix or a briefer summary in the
Quick Reference Card.
******************
S-REGISTER SUMMARY
USAGE
The default values are those users typically require. Change the settings
of an S-Register with the ATSr=n command, where r is the register and n
is a decimal value from 0-255:
ATS13=8 <Enter>
The modem does not perform a value-range check. Some values you select may
not work with some equipment, and you'll have to readjust the settings.
Some registers (S13, S14, S15, S16, S27, S34) are bit-mapped (bits 0-7).
For example, turning on bit 0 of S13 causes the modem to reset each time
the computer or terminal drops its Data Terminal Ready (DTR) signal.
Turning on bit 3 of S13 causes the modem, on receipt of DTR, to auto
dial the number stored at position 0 in NVRAM.
To turn on one or more bits in any bit-mapped register, use the total of
the values shown below. For example, S13=9 turns on bits 0 (value of 1)
and 3 (value of 8).
Alternatively, identify the bits to be turned on with the following format:
Sr.b=1, where r is the register and .b is the bit. This format does not
require knowledge of the bit's value. S13.0=1 .3=1 is the equivalent of
S13=9, above. To turn off a bit function, set it to zero: S13.0=0.
To display the contents of a register, use ATSr? as in this example:
ATS19? <Enter>
Register Default Function
S0 See DIP Sets the number of rings on which to
Switch 5 answer when in Auto Answer mode. S0=0 disables
Auto Answer, the same as DIP switch 5 ON (factory
setting). S0=1 enables Auto Answer and the modem
answers on the first ring.
NOTE: If DIP switch 5 is OFF and S0=0,
Auto Answer remains disabled.
S1 0 Counts and stores the number of rings from an
incoming call.
S2 43 Stores the ASCII decimal code for the escape code
character. Default character is <20>+<2B>. A value of
128-255 disables the escape code.
S3 13 Stores the ASCII decimal code for the Carriage
Return character. Valid range is 0-127.
S4 10 Stores the ASCII decimal code for the Line Feed
character. Valid range is 0-127.
S5 8 Stores the ASCII decimal code for the Backspace
character. A value of 128-255 disables the
Backspace key's delete function.
S6 2 Sets the number of seconds the modem waits
before dialing. If set to X2, X4, X6, or X7,
the modem dials as soon as it detects a dial
tone (fast dials). If there is no dial tone,
the modem observes the normal S6 timeout.
S7 60 Sets the number of seconds the modem waits for
a carrier. May be set for much longer duration if,
for example, the modem is originating an
international connection.
S8 2 Sets the duration, in seconds, for the pause (,)
option in the Dial command and the pause between
command re-executions (> and A> commands).
S9 6 Sets the required duration, in tenths of a
second, of the remote modem's carrier signal
before recognition by the Courier.
S10 7 Sets the duration, in tenths of a second, that
the modem waits after loss of carrier before
hanging up. This guard time allows the modem to
distinguish between a line hit, or other
disturbance that momentarily breaks the
connection, from a true disconnect (hanging up)
by the remote modem.
While we do not recommend connecting the modem to a
line with call waiting, if you have call waiting you
may wish to adjust this setting upward to prevent
the modem from misinterpreting the signal for a
second call as a disconnect by the remote modem.
A better alternative is to contact your phone
company to find out how to temporarily disable
call waiting.
S11 70 Sets the duration and spacing, in milliseconds,
of dialed tones.
S12 50 Sets the duration, in fiftieths of a second, of the
guard time for the escape code (+++) sequence.
S13 0 Bit-mapped register. Select the bit(s) you
want on and set S13 to the total of the
values in the Value column. For example,
ATS13=20 enables bit 2 (value = 4) and bit
4 (value = 16). Or use ATSr.b=0 (OFF) or 1
(ON). For example, ATS13.0=1 .3=1 turns
on bits 0 and 3. To turn a bit off, set that
bit to zero, as in ATS13.3=0.
Bit Value Result
0 1 Reset when DTR drops
1 2 Reverse normal Auto Answer operation:
on incoming RING, enter Originate Mode
and look for Answer tone
2 4 Disable 250 msec. pause before
result code display
3 8 On DTR signal, Auto Dial the number
stored in NVRAM at position 0
4 16 At power on/reset, Auto Dial number
stored in NVRAM at position 0
5 32 Disable HST (used for testing V.32
terbo in Dual Standard modems)
6 64 Disable MNP Level 3 (used for testing
Level 2)
7 128 Custom applications
S14 0 Bit-mapped register. Select the bit(s) you
want on and set S14 to the total of the values in
the Value column.
Bit Value Result
0 1 Disconnect on escape code
1-7 - Reserved
S15 0 Bit-mapped register. To set the register, see the
instructions for S13.
Bit Value Result
0 1 Disable the modem's extra high-
frequency equalization if it causes
problems on shorter-link calls--modems
only
1 2 Disable online fallback
2 4 Disable 450 bps back channel--HST only
3 8 Reset non-ARQ mode Transmit buffer
from 1.5K bytes to 128*
4 16 Disable MNP Level 4; retransmitting
the larger Level 4 data blocks may be
a problem if you expect a great number
of errors during a call
5 32 Set backspace key to delete
6 64 Some earlier 2400 bps MNP modems, not
made by U.S. Robotics or Microcom,
were not fully compatible with the MNP
protocol. If you have difficulty
making a successful 2400 bps MNP
connection with a remote MNP modem, it
may be because of this incompatibility.
Set S15 to 64 and try again to make the
connection.
7 128 Custom applications only
* The default 1.5K byte non-ARQ buffer allows data
transfer with X-and Ymodem-type file transfer protocols
without using flow control.
The 128-byte option allows remote users with slower
modems to stop data you're transmitting from scrolling
off their screens. When remote users send your computer
an XOFF (<Ctrl-S>) and you stop transmitting, the data
in transit from your modem's buffer doesn't exceed the
size of their screen.
S16 0 Bit-mapped test register. To set the register, see
the instructions for S13. For information on
testing, see Appendix H.
Bit Value Result
0 1 Analog Loopback
1 2 Dial test
2 4 Test pattern
3 8 Remote Digital Loopback
4 16 Reserved
5 32 Reserved
6 64 Reserved
S17 0 Reserved.
S18 0 Test timer for software-initiated loopback testing
(&Tn), disabled when S18 is set to 0. See Appendix
H. Used to set the duration of testing, in seconds,
before the modem automatically times out and
terminates the test.
S19 0 Sets the duration, in minutes, for the Inactivity
Timer. The timer activates when there is no data
activity on the phone line and at the timeout the
modem hangs up. S19=0 disables the timer.
S20 0 Reserved.
S21 10 Sets, in 10-millisecond units, the length of Breaks
sent from the modem to the computer or terminal.
Applies to ARQ mode only.
S22 17 Stores the ASCII decimal code for the XON character.
S23 19 Stores the ASCII decimal code for the XOFF character.
S24 150 Sets the duration, in 20-millisecond units, between
pulsed DSR signals when the modem is set to &S2 or
&S3. The default is 3 seconds.
S25 5 Sets DTR recognition time in 1/100th of a second
units.
S26 1 Sets the duration, in 1/100th of a second units, of
the delay between RTS and the modem's CTS response
in synchronous mode.
S27 0 Bit-mapped register. To set the register, see the
instructions for S13.
Bit Value Result
0 1 Enable ITU-T V.21 modulation at 300
bps for overseas calls. In V.21
mode, the modem answers both Bell
103 and V.21 calls, but only
originates V.21 calls.
1 2 Enable unencoded (non-trellis-coded)
modulation in V.32 mode; this option
is part of the ITU-T V.32
recommendation, but is rarely used.
2 4 Disable V.32 modulation; used for
testing HST modulation in Dual
Standard modems.
3 8 Disable 2100 Hz answer tone to allow
two V.42 modems to connect more
quickly.
4 16 See next page.
5 32 See next page.
6 64 Reserved.
7 128 Unusual software incompatibility.
Some software may not accept 7200,
12000, 14400, 16800, 19200 and 21600
bps result codes. This setting
disables the codes and displays the
9600 code instead. The call's
actual rate can be viewed on the
ATI6 screen.
Error control handshaking options:
select the total values of bits 4
and 5.
Bit 4 Bit 5 Result
0 0 Complete handshaking
sequence: V.42
Detection, LAPM
error control,
MNP
16 0 Disable MNP
0 32 Disable V.42
Detection and LAPM
16 32 Disable Detection
phase, if you know
that the remote modem
does LAPM, but not
the Detection phase.
S28 8 Sets the duration, in tenths of a second, of the
extra 3000/600 Hz answer tones sent during V.32
handshaking. This gives V.32 modems additional
time to connect in V.32 mode before timing out.
If there is difficulty answering older, manually
operated V.32 modems, for example, modems that
require a button to be pushed in order to dial,
try lengthening the duration of the extra tones.
Setting S28 to zero eliminates the extra tones,
resulting in a faster connect time if,
for example, the modem is set to use V.21
modulation (300 bps) or V.23 modulation
(1200 bps).
S29 20 Sets the duration, in tenths of a second, of the
answer tones sent during V.21 handshaking.
Default = 20 (2 seconds). This gives V.21 modems
additional time to connect in V.21 mode before
timing out.
S30-S31 0 Reserved.
S32 9 Sets the function for the voice/data switch. This
is not a bit-mapped register. Select the value for
the desired function, for example, ATS32=6.
Value Result
0 Disabled
1 Voice/data, Originate mode. See value 9.
2 Voice/data, Answer mode
3 Redial last number
4 Dial number stored at position 0
5 Auto Answer on/off toggle
6 Reset the modem
7 Initiate Remote Digital Loopback
8 Busy out phone line toggle
9 Default if a command string is stored with
the &ZC=string command. When voice/data
switch is pushed and &ZC has been enabled,
modem executes stored command string.
Otherwise acts like value 1, Originate
mode
NOTE: Only use the voice/data switch when the modem
is in Command mode.
S33 0 Setting this register to 1 (S33=1) enables a reduced
packet size.
S34 0 Bit-mapped register. See instructions for S13.
Bit Value Result
0 1 Disable V.32 bis. Used for
troubleshooting; U.S. Robotics'
Technical Support may require that
you disable V.32 bis for testing
purposes.
1 2 Disable the modem's enhanced,
proprietary V.32 bis modulation.
Used for troubleshooting.
2 4 Disable the faster retrains that
occur during proprietary V.32 terbo
modulation. Used for
troubleshooting.
3 8 Enable V.23. Required for some
British connections.
4 16 Change MR LED to DSR.
5 32 Enable MI/MIC; see Appendix G.
6 64 Disable the remote access busy
message.
7 128 Disable V.32 terbo.
S35-S37 0 Reserved.
S38 0 Sets the duration, in seconds, before a forced
hang-up and clearing of the Transmit buffer, when
DTR drops during an ARQ call. This is provided to
allow time for a remote modem to acknowledge receipt
of all transmitted data. Default = 0: the modem
immediately hangs up when DTR drops. If the modem
receives the ATH command, it ignores S38 and
immediately hangs up.
S39-S40 0 Reserved.
S41 0 Sets the number of allowable remote access login
attempts, thus enabling or disabling remote access.
The default setting of zero allows no remote login
attempts, thus disabling remote access. A value of
1 or greater enables remote access. If the number
of unsuccessful login attempts exceeds the limit set
by this register, the modem returns online and any
further login attempts during the remainder of that
connection are refused.
S42 126 Stores the ASCII decimal code for the remote access
escape character. The default character is a
tilde (~).
S43 200 Sets the duration, in fiftieths of a second, of the
guard time for the remote access (~~~~) sequence.
S44 15 Sets the duration, in seconds, of the delay between
when the modem senses loss of carrier and when it
attempts to re-establish a leased-line connection.
S45-S50 0 Reserved.
S51 0 Bit-mapped register. See instructions for S13.
Bit Value Result
0 1 Disable MNP/V.42 for
V.22 (1200 bps)
1 2 Disable MNP/V.42 for
V.22 bis (2400 bps)
2 4 Disable MNP/V.42 for
V.32/V.32 bis/V.32 terbo
(9600/14,400/19,200/
21,600 bps).
3-6 - Reserved
7 128 Custom Applications. Handset
Exclusion Delay. If the telephone
and modem share the same line, and
DTR is raised, the modem takes
control of the phone line and
disconnects the voice call. The
modem stays on hook for the duration
specified in S6 before it becomes a
data call.
Since there is no way to detect if
the telephone is in use, the S6 delay
occurs even if the telephone is not
in use.
The phone is re-enabled once the modem
returns on hook.
S52 0 Reserved.
S53 0 Bit-mapped register. Select the Dial Security
features you want enabled by setting S53 to the
total of the values in the Value column in the
table below. For example, S53=3, enables Dial
Security with prompting. S53=5 enables Dial
Security, and local-access password protection.
Or use ATSr.b=0 (OFF) or 1 (ON). For example,
ATS53.0=1 .2=1 turns on bits 0 and 2. To turn a
bit off, set that bit to zero, as in ATS53.2=0.
Bit Value Result
0 1 Dial security enabled
1 2 Prompting enabled
2 4 Local-access password
protection enabled
NOTE: In addition, enabling local access password
protection disables the &Zn=s command which stores
up to ten phone numbers because stored phone numbers
occupy the same space in NVRAM as the dialback
numbers for Dial Security accounts.
S54 0 Symbol rate bit-mapped register used primarily by
U.S.Robotics Technical Support for debugging
purposes.
Bit 6 (ATS54.6=1) disables Call Indicate (CI).
Bit 7 (ATS54.7=1) disablesV.8.
S55 0 Trellis code bit-mapped register used primarily
by U.S.Robotics Technical Support for debugging
purposes.
S56 0 Bit-mapped register primarily used by U.S.Robotics
Technical Support for debugging purposes.
Bit 6 (ATS56.6=1) disables V.34 modulation.
Bit 7 (ATS56.7=1) disables V.FC modulation.
S57 0 Reserved for German operations.
Appendix C--Alphabetical Command Summary
Additional command summaries are in Chapter 4, on the bottom panel of the
modem, and in the Quick-Reference Card.
*****************
COMMAND SET USAGE
Follow these guidelines:
1. Your software must be loaded and if you are using a computer, it must be
in Terminal mode.
Some communications programs put the computer in terminal mode
automatically when they are loaded. Others require you to display a
communications terminal screen, press a Function key, or perform some
other operation. Refer to your communications software documentation
for instructions.
In Terminal mode the computer acts as if it were a standard terminal
such as a teletypewriter, rather than a data processor. Keyboard
entries go directly to the modem, whether the entry is a modem command
or data to be transmitted over the phone lines. Received data is
output directly to the screen.
2. Type commands in either upper or lower case, not a combination (AT or
at--not At).
3. All commands except A/, A> and +++ are preceded by the AT (attention)
prefix and are executed with the Enter/Carriage Return key (<Enter>).
4. Command length = 60 characters maximum. The modem doesn't count the
AT prefix, Carriage Return character, or spaces. It counts (but
doesn't act on) punctuation such as hyphens and parentheses.
5. A missing numeric parameter is assumed to be zero, as in the command
to hang up: ATH <Enter> is the equivalent of ATH0 <Enter>.
Example (spaces are not required, but are added here for readability):
AT &K3 X2 DT 071 312 1234 <Enter>
AT Attention; a command follows.
&K3 Disable MNP5 data compression; use only V.42 bis compression.
X2 Use the X2 result code subset.
DT Dial the following number using tone dialing.
<Enter> Execute the commands.
NOTE: The defaults listed are based on the modem's shipping
configuration: load from nonvolatile random access memory (NVRAM),
DIP switch 10 OFF, which is the same as the &F1 configuration template.
For a complete listing of default configuration templates, see Appendix B.
*****************
Basic Command Set
+++ Escape code operations. Once the modem is online to another system,
the only command it recognizes is an escape code of three typed
pluses, which forces the modem back to Command mode. Do the
following when issuing the command:
* Wait one second after sending the last item of data
* Type: +++
* Wait one second before typing any data
Do not type the AT prefix or a Carriage Return. The guard time of
one second before and after the code prevents the modem from
misinterpreting the occurrence of +++ in the transmitted data
stream.
If necessary, the character used in the escape code or the
duration of the guard time can be changed by resetting Register
S2 or S12. See the S-Register Summary in Appendix B.
In response to +++ the modem returns to Command mode. However, it
keeps the line open or hangs up, depending on the setting of DIP
switch 9:
DIP Switch 9 Response to +++
OFF Modem goes on hook (hangs up), sends NO CARRIER
result code (factory setting)
ON Modem maintains connection (Online-Command mode),
sends OK result code
The factory setting (OFF) forces an automatic disconnect when you
issue +++. An advantage of this is that you are not likely to
inadvertently run up an all-night phone bill.
Set DIP switch 9 ON if you want the modem to respond to +++ by
entering Online-Command mode, enabling it to execute commands and
return online. (See the O command later in this appendix.)
> If you know the modem you are calling is frequently busy, include
the Repeat command in the Dial string, as follows:
AT > DT 1234567 <Enter>
or
AT DT 1234567 > <Enter>
The modem enters Repeat mode, dials the number, waits 60 seconds
for a carrier (default), and hangs up. Then after a two-second
pause, it redials.
The cycle continues until the modems connect or the modem reaches
a maximum of 10 attempts.
A Force Answer mode when the modem hasn't received an incoming call.
A/ Re-execute the last issued command. A/ doesn't take the AT prefix
or a Carriage Return, and can be used to redial.
A> This command combines the features of both the A/ and > commands.
The modem enters Repeat mode and redials the Dial string in the
command buffer. Like the A/ command, A> does not take the AT
prefix or a Carriage Return.
AT Attention command prefix. Use AT alone to test for the OK result
code. AT must prefix all commands except A/, A> and +++.
Any Terminate the current dialing operation resulting from an
key issued Dial command; terminate Repeat mode (> or A>).
Bn Handshake options for international calls above 1200 bps.
B0 ITU-T (formerly CCITT) answer sequence. Default. This is
required to answer all V.32-type calls as well as calls from
overseas.
B1 Bell answer tone. This setting selects HST modulation in
Dual Standard modems; but should only be used if the modem is
not required to answer V.32-type calls.
NOTE: This setting is required for HST cellular calls.
Cn Transmitter enabled/disabled.
C0 Transmitter disabled; receive-only condition.
C1 Transmitter enabled (Default).
Dn Dial the specified phone number; also execute Dial options.
The maximum number of characters allowed is 36, including the AT
prefix, punctuation and spaces. The Carriage Return (Enter key)
isn't counted as a character.
NOTE: With the exception of the Dial options, the modem ignores
any commands issued after D in the same command string.
D Dial the number that follows and enter Originate mode. Optional
parameters:
P Pulse dial (Default).
T Tone dial.
, (Comma) Pause for 2 seconds before continuing to dial.
; Return to Command mode after dialing.
" Dial the letters that follow (in an alphabetical phone number).
! Transfer a call (flash the switch-hook). This command applies
to modems in installations where other modems share the phone
line. The modem flashes the switch-hook (goes off hook 0.5
seconds, on hook for 0.5 seconds and off hook again) to dial
the specified extension.
W This command is useful in situations where you must wait for a
second dial tone before continuing dialing.
@ Wait for an answer (with X3 or higher). The @ command can be
used in the Dial string to tell the modem to detect at least
one ring, wait for five seconds of silence at the other end of
the call, and then continue to execute the Dial string.
/ A slash (/) causes a pause of only 125 milliseconds.
R Reverse frequencies. This command allows calls to an
originate-only modem. It reverses the modem's originate/answer
frequencies, forcing the Courier to dial out at the answer
frequency.
DL Dial the last-dialed number. The modem stores each Dial command
until it receives the next Dial command. Use DL instead of A/,
described on the next page, if you wish to send the modem non-Dial
commands before dialing again.
DSn Dial the number stored in nonvolatile random access memory at
position n, where n = 0-9.
En Command mode local echo. Enables/disables the display of your
typed commands. If double characters appear on the screen, both the
modem's local echo and your software's local echo are on.
The Courier is shipped with DIP switch 4 OFF, enabling local echo.
The En command controls the local echo for a current session,
independently of the switch setting.
E0 Command mode echo OFF. The modem does not display keyboard
commands.
E1 Command mode echo ON.
Fn Online local echo. This command causes the modem to display a copy
of the data it is transmitting to another system.
F0 Online echo ON. Sometimes called half duplex. As the modem
transmits data to a remote system, it also sends a copy of the
data to the screen.
F1 Online echo OFF. Sometimes called full duplex. Default.
Hn On/off hook control.
H0 Hang up (go on hook).
H1 Go off hook.
In Inquiry
I0 Display product code
I1 Display results from ROM checksum
I2 Display results from RAM test
I3 Display the duration of the last call
I4 Display current modem settings
I5 Display NVRAM settings
I6 Display Dial diagnostics summary of the last call
I7 Display product configuration information
I8 Reserved
I9 Reserved
I10 Display dial security account status information
I11 Display a high speed connection report
Kn Modem clock operation: Call-duration or Real-time mode. Displayed
with ATI3 and ATI6 commands.
K0 Display current call-duration if online. Display last
call-duration if offline. Default.
K1 Return actual time at ATI3. Clock is set using ATI3=HH:MM:SS K1.
Ln Speaker volume control (internal modems only)
L0 Low
L1 Low
L2 Medium (default)
L3 High
NOTE: External modems will return an OK message to this command,
but the volume will not change. The volume button must be used to
alter volume.
Mn Speaker (audio monitor).
M0 The speaker is always OFF.
M1 The speaker is ON until carrier is established (Default).
M2 The speaker is always ON, including during data transfer.
M3 The speaker is ON after the last digit is dialed and remains
ON until carrier is established.
On If DIP switch 9 is ON (on detection of the escape code the modem
maintains the connection), you can issue commands and then toggle
the modem back online with the On command.
There are two ways to return online.
ATO0 Return online (normal).
ATO1 Return online and retrain. Use to have the modem
re-synchronize if there were errors in a non-ARQ data transfer.
Qn Enable/suppress the display of result codes. The Courier is
shipped with DIP switch 3 ON, to display result codes. Use the Qn
command to control the display for a current session, independently
of the switch setting.
Q0 Result codes displayed.
Q1 Result codes suppressed (quiet).
Q2 Result codes suppressed in Answer mode.
Sr=n Set S-Register value: r is any S-Register; n must be a decimal
number between 0 and 255.
Sr.b=n Alternative command for setting bit-mapped registers: r is the
bit-mapped register; .b is the bit; n is 0 (off) or 1 (on).
Sr? Query contents of register r.
Vn Return result codes in words or numbers (Verbal/Numeric mode).
V0 Numeric mode.
V1 Verbal mode.
Xn Result code set options. Use the following table (Default = X7,
all codes except 12/VOICE). For result codes in synchronous
operations, see Appendix F.
Setting
Result Codes X0 X1 X2 X3 X4 X5 X6 X7
0/OK <20> <20> <20> <20> <20> <20> <20> <20>
1/CONNECT <20> <20> <20> <20> <20> <20> <20> <20>
2/RING <20> <20> <20> <20> <20> <20> <20> <20>
3/NO CARRIER <20> <20> <20> <20> <20> <20> <20> <20>
4/ERROR <20> <20> <20> <20> <20> <20> <20> <20>
5/CONNECT 1200 <20> <20> <20> <20> <20> <20> <20>
6/NO DIAL TONE <20> <20> <20> <20>
7/BUSY <20> <20> <20> <20> <20>
8/NO ANSWER <20> <20> <20> <20> <20>
9/RESERVED
10/CONNECT 2400 <20> <20> <20> <20> <20> <20> <20>
11/RINGING <20> <20> <20>
12/VOICE <20> <20>
13/CONNECT 9600 <20> <20> <20> <20> <20> <20> <20>
18/CONNECT 4800 <20> <20> <20> <20> <20> <20> <20>
20/CONNECT 7200 <20> <20> <20> <20> <20> <20> <20>
21/CONNECT 12000 <20> <20> <20> <20> <20> <20> <20>
25/CONNECT 14400 <20> <20> <20> <20> <20> <20> <20>
47/CONNECT 16800 <20> <20> <20> <20> <20> <20> <20>
85/CONNECT 19200 <20> <20> <20> <20> <20> <20> <20>
91/CONNECT 21600 <20> <20> <20> <20> <20> <20> <20>
99/CONNECT 24000 <20> <20> <20> <20> <20> <20> <20>
103/CONNECT 26400 <20> <20> <20> <20> <20> <20> <20>
107/CONNECT 28800 <20> <20> <20> <20> <20> <20> <20>
Functions
Adaptive Dialing <20> <20> <20> <20> <20> <20>
Wait for 2nd Dial Tone (W) <20> <20> <20> <20> <20>
Wait for Answer (@) <20> <20> <20> <20> <20>
Fast Dial <20> <20> <20> <20>
Z Software reset to NVRAM settings when DIP switch 10 is OFF (factory
setting). If DIP switch 10 is OFF, the modem resets to the &F0
configuration template, with no flow control.
*************************
Ampersand (&) Command Set
&An Enable/disable additional result code subsets. See the Xn command.
&A0 ARQ result codes are disabled.
&A1 ARQ result codes enabled.
&A2 Additional VFC, HST, or V32 modulation indicator.
&A3 Additional error control indicator (LAPM, HST, MNP, SYNC,
or NONE) and data compression type (V42BIS or MNP5).
Default.
&Bn Serial port rate variable or fixed.
&B0 Variable rates.
&B1 Fixed rate. Default. The modem always communicates with the
computer at the rate at which you have set the terminal or
software, regardless of the connection rate.
This setting is not affected by the &N setting. However, the
serial port rate must be equal to or higher than the &Nn rate.
&B2 Fixed for ARQ calls/Variable for non-ARQ calls. Answer mode
only. When the modem goes off hook and connects in ARQ mode,
it shifts its serial port rate up to a user-specified rate,
for example, 38.4K bps. If the connection is not under error
control, the modem behaves as if it were set to &B0 and
switches its serial port rate to match the connection rate of
each call.
&Cn Carrier Detect operations. At power-on and reset, the modem
operates according to the setting of DIP switch 6. This command
is not stored in nonvolatile memory as a power-on/reset default.
&C0 CD override, CD always ON.
&C1 Normal CD operations. The Courier sends a CD signal when
it connects with another modem and drops the CD when it
disconnects.
&Dn Data Terminal Ready (DTR) operations. At power-on and reset, the
modem operates according to the setting of DIP switch 1. This
command is not stored in nonvolatile memory as a power-on/reset
default.
&D0 DTR override. The modem operates as though the DTR is always ON.
&D1 Advance usage: If issued before connecting with another modem,
the modem can enter online command mode during a call by
toggling DTR. &D1 functions similarly to the escape code
(+++), except that this setting is independent of DIP switch 9.
If DIP switch 1 is ON (DTR override) when you issue the &D1
command, the DTR override is automatically turned off.
However, if you change the setting of DIP switch 1 after
issuing &D1, the DIP switch setting tales precedence.
Return online with the On command, or hang up with the Hn
command.
&D2 Normal DTR operations. The terminal or computer must send a
DTR signal for the modem to accept commands. Dropping DTR
terminates a call.
&Fn The modem is shipped with four configurations (templates),
&F0-&F3, stored in permanent nonprogrammable memory (ROM).
Appendix B includes configuration listings for each template.
Any one of the templates may be loaded into current memory
(AT &Fn) or written to nonvolatile memory and reset default
(AT &Fn &W). Note, however, that &F0 is always loaded into
memory if DIP switch 10 is ON.
&F0 Load No Flow Control template settings
&F1 Load Hardware Flow Control template settings (Default)
&F2 Load Software Flow Control template settings
&F3 Load HST Cellular template settings
&Gn This setting applies only to overseas calls at 2400 or 1200 bps.
British phone switching systems require the modem to send an 1800
Hz guard tone after it sends an answer tone. Some other European
phone networks require a 550 Hz guard tone. Guard tones are not
used in the United States or Canada.
&G0 No guard tone. This is used in the U.S. and in Canada (Default).
&G1 This sets a 550 Hz guard tone, and is used in some European
countries.
&G2 This sets an 1800 Hz guard tone, and is used in the U.K. and
some Commonwealth countries. &G2 requires the B0 setting.
&Hn Transmit data flow control is for data transmitted to the modem
by its attached computer or terminal. The modem monitors its
buffer as data comes from the computer or modem. If the buffer
approaches 90% capacity, the modem signals the computer or terminal
to stop transmitting. When the modem has sent enough data over
the link to half empty the buffer, it signals the computer or
terminal to resume transmitting.
&H0 Transmit Data flow control disabled.
&H1 Hardware flow control. Default. Requires that your computer
or terminal and software support Clear to Send (CTS) at the
RS-232 interface.
&H2 Software flow control. Requires that your software support
XON/XOFF signaling.
&H3 Use both hardware and software flow control. If you are unsure
about what your equipment supports, select this option.
&In Received data software flow control.
&I0 Disables XON/XOFF flow control of received data. Default.
&I1 The Courier acts on your typed XON/XOFF commands, Ctrl-S or
Ctrl-Q, and passes them to the remote computer.
&I2 The Courier acts on your XON/XOFF commands, but removes them
from the data stream instead of passing them to the remote
computer. This is the recommended setting for ARQ mode.
&I3 Hewlett Packard--Host mode. Applies only to modems attached to
an HP mainframe that uses the ENQ/ACK protocol. Use in ARQ
nmode only. See Appendix G.
&I4 Hewlett Packard--Terminal mode. Applies only to modems
attached to terminals in an HP system that uses the ENQ/ACK
protocol. Use in ARQ mode only. See Appendix G.
&I5 This setting is designed to enable flow control on the phone
link when the connection is not under error control. For this
to work for you, the remote modem must have &I5 capability.
&Kn Enable/disable data compression.
&K0 Data compression disabled.
&K1 Auto enable/disable. Default. The modem enables compression
if the serial port rate is fixed, &B1, and disables compression
if the serial port rate follows the connection rate, &B0,
because compression offers no throughput advantage when the
serial port and connection rates are equal. Compression may
even degrade throughput.
&K2 Data compression enabled. Use this setting to keep the modem
from disabling compression.
&K3 Selective data compression. The modem negotiates only for
V.42 bis compression, and disables MNP Level 5 (MNP5)
compression. Use this setting to transfer 8-bit binary
files, .ZIP files, and other files that are already compressed.
&Ln Normal/Leased phone line.
&L0 Normal phone line. Default.
&L1 Leased line; enables modem to reconnect if disconnected.
&L2 Cellular operations; with B1, enables HST Cellular mode.
&Mn Enable ARQ (error control) or synchronous protocols. Both your
modem and the remote modem must use the same protocol.
&M0 Normal mode, no error control. Due to the nature of phone
line channels, this is never recommended for calls above 2400
bps.
&M1 This setting is exclusive of the modems' error control and is
used only for online synchronous mode without V.25 bis. See
Appendix F for more information.
&M2 Reserved.
&M3 Reserved.
&M4 Normal/ARQ mode. Default. If an ARQ connection isn't made,
the modem operates in Normal mode, as though it were set to &M0.
&M5 The modem enters ARQ asynchronous mode. The modem hangs up if
an ARQ connection cannot be made.
&M6 The modem enters V.25 bis synchronous mode, using a character-
oriented link protocol similar to BISYNC. See Appendix F for
more information.
&M7 The modem enters V.25 bis synchronous mode, using the HDLC link
protocol.
&Nn Connection rate variable or fixed.
&N0 Variable rates. Default. The Courier negotiates with the
remote modem for the highest possible connection rate,
depending on the capabilities of the remote modem. This is
the recommended setting.
&N1- Fixed rate. The modem only connects if the remote modem is
&N14 operating at the same rate. If not, the modem hangs up. If
you wish, you can filter out calls at other than a specific
rate, for security or other reasons, by fixing the connection
rate.
The connection rate must always be lower than, or equal to,
the serial port rate, never higher.
The options are as follows.
&N1 300 bps &N9 16.8K bps (HST, terbo,
&N2 1200 bps V.FC, and V.34 only)
&N3 2400 bps &N10 19.2K bps (terbo, V.FC,
&N4 4800 bps and V.34 only)
&N5 7200 bps &N11 21.6K bps (terbo, V.FC,
&N6 9600 bps and V.34 only)
&N7 12K bps &N12 24K bps (V.FC and V.34 only)
&N8 14.4K bps &N13 26.4K bps (V.FC and V.34 only)
&N14 28.8K bps (V.FC and V.34 only)
&Pn This command sets the ratio of the off-hook/on-hook (make/break)
interval for pulse dialing. The default sets the modem for use
in North America. The ratio must be changed if the modem is used
in the United Kingdom and some Commonwealth countries.
&P0 Make/break ratio, U.S./Canada: 39%/61%. Default.
&P1 Make/break ratio, United Kingdom, some Commonwealth
countries: 33%/67%.
&Rn Received data hardware (RTS) flow control
&R0 Delay Clear to Send Response after Request to Send signal
(RTS/CTS delay).
&R1 The modem ignores RTS. This setting is required if your
computer or terminal or software does not support RTS.
&R2 Hardware flow control of received data enabled. Default.
The modem sends data to the computer or terminal only on
receipt of the RTS signal.
&Sn The modem sends the computer or terminal a Data Set Ready (DSR)
signal via the RS-232 interface. (Data Set is industry jargon for
modem.)
&S0 DSR is always ON (override). Default.
&S1 In Originate mode, the modem sends the DSR after it dials,
when it detects the remote modem's answer tone. In Answer
mode, the modem sends the DSR after it sends an answer tone.
&S2 This option is for specialized equipment such as automatic
callback units. On loss of carrier, the modem sends a pulsed
DSR signal with Clear to Send (CTS) following Carrier Detect (CD).
&S3 This is the same as &S2, but without the CTS following CD.
&S4 The modem sends the computer a DSR signal at the same time as
it sends the Carrier Detect (CD).
&S5 CTS follows Carrier Detect with DSR normal
&Tn Modem testing
&T0 End test
&T1 Initiate Analog Loopback (AL) testing
&T2 Reserved
&T3 Initiate Local Digital Loopback (LDL) testing
&T4 Grant Remote Digital Loopback (RDL)
&T5 Deny RDL
&T6 Initiate RDL testing
&T7 Initiate RDL with self test and error detection
&T8 Initiate AL with self test and error detection
&W Write the curent settings to NVRAM.
&Xn Synchronous transmit clock timing signals setting. Determines
whether the modem or DTE will generate the timing signals.
&X0 The Courier is the source of the Transmit clock timing
signals and sends them to your DTE over the RS-232 interface.
The DTE rate will follow the connection rates. Default.
&X1 The DTE is the source of the Transmit clock timing signals
and sends them to the Courier over the RS-232 interface. This
setting is used typically in leased line multiplexed operations.
(Multiplexors divide the phone channel so that the channel
carries several calls at the same time.)
The DTE ignores the Courier's clock timing signals and
negotiates the DTE and connection rates.
&X2 The Courier's Receiver clock is the source of the timing
signals. The signals are looped to the Transmit clock and
sent to your DTE over the RS-232 interface. This setting is
only used in those systems that require synchronization of
data flowing in both directions.
&Yn Break handling. This command allows you to send a break to abort
data transfer without disconnecting from the phone link.
&Y0 Destructive, don't send Break.
&Y1 Destructive, expedited (Default).
&Y2 Nondestructive, expedited.
&Y3 Nondestructive, unexpedited; modem sends Break in sequence
with data received from computer or terminal.
&ZC? Display the stored command string.
&ZC=s Write the following command string s to NVRAM. The command string
may be up to 40 characters long; spaces are not counted. This
command can be used so that you can call another modem without
loading your communications software.
After storing a command, you can program the voice/data switch
to execute the stored command string when pressed. The following
example assigns a command string that displays the link diagnostics
screen when you press the voice/data switch.
AT&ZC=I6 <Enter>
The function of the voice/data switch is determined by the setting
of Register S32, as described in Appendix G. Set the voice/data
switch function to execute stored command string by setting
Register S32 to 9 with the following command:
ATS32=9 <Enter>
Note that you can reset the voice/data switch at any time to one of
the other available functions. Additionally, you can overwrite the
stored command string with a new one at any time.
Once you've stored your command string and set Register S32, all
you need to do is press the voice/data switch whenever you want
the command string executed.
&Zn=s This command stores up to ten numbers, where n is the position
0-9 in nonvolatile memory, and s is the phone number string.
The number-string may be up to 36 characters long, including
any Dial command options.
AT &Z2=555-6789 <Enter>
Do not include modem settings in the &Zn string. If the call
requires a special setting, insert it in the command string
before the DSn command. In the following example, &M0 (no
error control) is inserted before the Dial command:
AT&M0 DS2 <Enter>
NOTE: The &Zn=s command functions differently when Dial Security
is enabled. See Appendix D for more information.
&Zn? Display the phone number stored in NVRAM at position n (n = 0-9).
*******************
Percent Command Set
%An Create and configure security accounts. See Appendix D.
%Bn Remotely configure the Courier's serial port rate. See Appendix D.
%B0 110 bps %B6 9600 bps
%B1 300 bps %B7 19,200 bps
%B2 600 bps %B8 38,400 bps
%B3 1200 bps %B9 57,600 bps
%B4 2400 bps %B10 115,200 bps
%B5 4800 bps
%Cn Remote configuration control. See Appendix D.
%C0 Defer configuration. This is the default. Configuration
changes are deferred until the call is ended; they take effect
for ensuing connections. You do not need to enter this
command; it is the default unless you enter %C1 or %C2.
%C1 Restore configuration. Use this command to cancel any
configuration changes made during remote access, and restore
the original configuration. However, commands that have been
written to NVRAM (with &W) will not be restored to their
previous settings. Additionally, if you have forced immediate
configuration changes (with %C2), those changes cannot be
reversed with %C1.
%C2 Execute configuration. Use this command to force configuration
changes to take effect immediately, during the current
connection. We recommend against forcing immediate
configuration changes unless absolutely necessary, as this
can result in an unreliable connection or even a loss of
connection.
%E=n Make security system edits. See Appendix D.
%E=1 Erase local access password.
%E=2 Erase autopass password.
%E=3 Erase passwords in accounts 0<>9.
%E=4 Erase phone numbers in accounts 0-9.
%E=5 Disable Account, Dialback, and New Number fields in
accounts 0-9 disabled.
%Fn Remotely configure data format. See Appendix D.
%F0 No parity, 8 data bits.
%F1 Mark parity, 7 data bits.
%F2 Odd parity, 7 data bits.
%F3 Even parity, 7 data bits.
%L= Assign an account password as the local access password. See
Appendix D.
%N Works in conjunction with &Xn in synchronous mode. If the modem
is set so that it is the source of the Transmit clock timing
signals (&X0--default), the %Nn commands set the computer or
terminal-to-modem V.25 bis clock speed. If the modem is set to
&X1, the computer is the source of the Transmit clock signals.
If %Nn is set to 0 or 1, you will receive an error message, since
they are not valid values. The %Nn rates are as follows:
%N0 Reserved %N6 9600 bps (default)
%N1 Reserved %N7 12.K bps
%N2 1200 bps %N8 14.4K bps
%N3 2400 bps %N9 16.8K bps
%N4 4800 bps %N10 19.2K bps
%N5 7200 bps
%Pn= Disables password security (n=0 or 1) when no character follows
the equal sign. See Appendix D.
%Pn=s Specify the following password string (s) for viewing privileges
only (n = 0) or view and configuration privileges (n= 1). See
Appendix D.
%Pn? Display password n. See Appendix D.
%S=n Obtain access to security accounts without disabling security.
See Appendix D.
%T Enables the modem, when off hook, to detect the tone frequencies
of dialing modems. %T is meant primarily for use with network
applications, but may also be integrated into certain software
programs. For example, %T could be used in a security program
to identify incoming tone security codes.
To enable %T, type ATH1 <Enter> to force the modem off hook.
Then type AT%T <Enter>.
To return the modem to Command mode, press any key or drop the
computer's or terminal's DTR signal. The modem responds OK.
%V=PWn Assign the password in account n in your Courier modem<65>s security
as your autopass password. See Appendix D.
Appendix D--Dial Security and Remote Access Operations
_____________________________________________________________________
DIAL SECURITY OPERATIONS
Dial Security is designed to protect networks and data centers from
unauthorized access. The kind of security provided by the Courier modem
is different from other kinds of dial security where software is used by
the computer to control user access. The Courier<65>s Dial Security is set
up in the modem<65>s firmware, so access is controlled from modem to modem.
Setting up this kind of security requires action at both the host and
remote modem sites. This appendix contains instructions for both
operations.
WARNINGS:
If you want to set up Security on your Courier modem, you must complete
the steps below in the order listed:
1. Set up your own security account:
* Set up your local access password
* Enable local access password protection
2. Set up remote user accounts.
3. Enable Dial Security.
You must set up your local access security information before enabling
Dial Security and allowing remote calls, as outlined under Set Up Your
Security Account in what follows.
Be sure to remember your local access password; if you enable security
and forget your local access password, you risk being locked out of
your system.
********
Overview
The Courier<65>s Dial Security allows you to configure up to 10 Security
accounts. Each security account is stored in nonvolatile memory (NVRAM)
and may be set up in one of three ways:
* Automatic password access
* Prompted password access
* Password with Dialback protection
Autopass
Autopass is the term we use for the basic implementation of Dial Security
in the Courier modem. It is in effect whenever Dial Security is enabled.
To use autopass alone, the following requirements must be met:
* Both host and remote modems must be U.S. Robotics modems with
Dial Security enabled.
* The connection must be under V.42 error control (both modems must be
set to &M4 or &M5).
When the remote modem is set for Dial Security, it automatically
includes an autopass password (configured by the remote user to be
compatible with the host modem<65>s security) in its V.42 error control
request. The host modem checks all the enabled passwords in its
security accounts for a match.
If the remote user has set up the modem with an invalid password, the host
modem returns an INVALID PASSWORD message and hangs up.
If the remote user failed to enable Dial Security on the remote Courier,
the host Courier will not accept the call unless prompting (below) is
enabled on the host modem.
Prompting
While the use of autopass (above) is restricted to U.S. Robotics Dial
Security modems, prompting allows secured connections with any remote
modem whose user has been assigned an allowed password. When prompting
is enabled, and the host modem doesn<73>t receive an autopass password, it
prompts the remote user for a password. The host modem checks the
received password against each of its active Security accounts. If the
password is valid, a secure connection is completed.
If the password is invalid, the host modem prompts twice more before
disconnecting.
If there are no password attempts at the remote end, the host modem
times out after 60 seconds and disconnects.
NOTE: There is no prompting capability in synchronous mode.
Prompting is more flexible than autopass because it:
* doesn't require a remote modem to have U.S. Robotics Dial Security.
* doesn't require a V.42 connection, so remote modems without V.42
error control capabilities can connect.
Optional Dialback
Dialback offers an additional layer of security. When the host modem
receives a valid password that matches an account and Dialback is enabled,
the host first disconnects. The remote user receives a NO CARRIER message.
Then the host modem dials back the remote modem.
Typically, the Dialback number is stored in the Security account<6E>s phone
number field. However, if the security account has been set up to allow
a new number, the host prompts the remote user for the new number before
hanging up, and then dials back.
In order to use dialback, Dial security and prompting must be enabled.
****************************************
WHAT THE HOST MODEM OPERATOR NEEDS TO DO
Complete the steps below in the order listed:
1. Set up your own Security account.
2. Set up Security accounts for your remote users.
3. Enable Dial Security.
4. Maintain Security accounts.
****************************
Set Up Your Security Account
Security accounts are set up via an AT command line structure, rather
than a screen format.
1. Set up your Security account using one of 10 accounts (numbered 0-9).
Each account has five possible fields, as shown in the following table.
Password Account Dialback Allow New Dialback
Enabled Enabled Enabled Number Number
8 chars. max. YES/NO YES/NO YES/NO Up to 37
ASCII 37-127 characters
case sensitive* (0-9)
BILL Y Y N 1-419-555-5555
* If "BILL" is the password, "Bill" is an invalid entry.
Use the %An= command and format (below) to set up accounts, where n is the
account number, 0-9. The fields in the above table are entered after the
equal sign, each separated by a comma, as in the following example for
account 0 with the password BILL.
WARNING: Do not insert spaces between commas or between fields and commas.
Spaces will invalidate the command.
AT%A0=BILL,Y,Y,N,1-419-555-5555 <Enter>
This example instructs the modem to store the configuration for account 0:
password (BILL), account enabled (Y), dialback enabled (Y), allow a new
number (N), and the dialback phone number.
NOTE: The %An= command is automatically written to NVRAM and does not
require an &W.
Some accounts may have fewer security options. The following example sets
the password (Judy) and enables account 1 without any dialback options.
AT%A1=Judy,Y,,, <Enter>
Each security function can be configured or modified independently. If a
field is to remain as is, just insert a comma, as shown in the following
command. It allows the remote user to supply a new Dialback number
different from the one stored in the original account record.
AT%A0=,,,Y, <Enter>
2. Set up your local access password. This password protects the Security
accounts from unauthorized users. When this protection is enabled, you
cannot view, modify, or tamper with the Security accounts unless you
enter the correct local access password. The local access password must
be chosen and protection must be enabled before Dial Security is enabled.
In the following example, the local access password is the same as the
password in account 0.
AT%L=PW0 <Enter>
********************************
Set up Accounts for Remote Users
Once your account is configured and password protection has been enabled,
you can set up the remote user accounts. Use the %An= command (using the
same guidelines you used to set up the system administrator<6F>s account in
Step 1 of the previous section) to set up remote user accounts.
Once security accounts have been enabled, you are responsible for
communicating valid password information to your remote users.
********************
Enable Dial Security
Once you have completed the previous steps, you are ready to enable Dial
Security.
When you enable Dial Security, you must choose either autopass or prompting
as the security method. You must know what types of modems remote users
are using and set the Dial Security parameters accordingly. Autopass is
limited to U.S. Robotics modems with Dial Security, but prompting is not.
1. Register S53 is the bit-mapped register used to enable Dial Security.
The &W command must be used to save Register S53 settings to NVRAM.
Otherwise, when the computer is powered off and on again, or the modem
is reset using ATZ, it will default to S53=0, Dial Security disabled.
To enable Dial Security with autopass and local access password
protection, but without prompting, type the following command:
AT S53.0=1 .2=1 &W <Enter>
The following command enables Dial Security with autopass, prompting,
and local access password protection.
AT S53.0=1 .1=1 .2=1 &W <Enter>
NOTE: Enabling local access password protection disables the &Zn=s
command that stores up to ten phone numbers. Stored phone numbers
occupy the same space in NVRAM as the dialback numbers for Dial Security
accounts, and cannot be used when Dial Security is enabled.
If the local access password is not protected, the &Zn=s command
overwrites the corresponding Dial Security dialback number. For
example, the following command overwrites the dialback number for
account 5:
AT &Z5 = 555-8976 <Enter>
However, if the local access password is protected, and a user tries to
use the &Zn=s command, an ACCESS DENIED message is displayed.
WARNING: Be sure DIP switch 10 is OFF so the modem will load the
settings stored in NVRAM. If someone sets DIP switch 10 ON, the low
performance template settings (&F0) are loaded, and Dial Security is
disabled. If this should happen, reset DIP switch 10 to OFF, power
off the modem and power it back on, or reset the modem by typing ATZ
<Enter> so that the proper settings take effect.
**************************
Maintain Security Accounts
Once the local access password is set and protected, the system
administrator is the only one who can access account information. To
modify or change account information, use the %S= and %E= commands
described next.
Account Access (%S)
Once Dial Security is enabled, you can access accounts by entering the
local access password using the %S= command, which allows access to the
accounts by disabling local security.
AT%S=(your local access password) <Enter>
NOTE: The modem echoes the local access password, which is case sensitive.
The system will accept an invalid password entry, but will lock you out
from the modem<65>s security commands. For example, if the password is Bob,
but you enter BOB, an OK is displayed. However, if you try to type a
security command (for example, ATI10 <Enter> to view accounts), an ACCESS
DENIED message is displayed.
Account Status
Once access has been granted, you can view account information by typing
the I10 option of the Inquiry (I) command:
ATI10 <Enter>
Remote users may only use this command during a remote access session if
local access security is disabled.
Erasing Account Information (%E)
Use the %E=n command to make system edits.
%E=1 Erase local access password.
%E=2 Erase autopass password.
%E=3 Erase passwords in accounts 0-9.
%E=4 Erase phone numbers in accounts 0-9.
%E=5 Disable Account, Dialback, and New Number fields in accounts 0-9.
To edit or overwrite an individual account, or an individual account field,
use the %An= command described in Set Up Your Security Account, earlier
in this appendix.
Remote Configuration
Dial Security accounts may be configured remotely. See Configuring Dial
Security Remotely at the end of this appendix.
**********************************
WHAT THE REMOTE CALLER NEEDS TO DO
When remote users want to call in to your Courier (assuming you have
enabled Dial Security), they must contact you to obtain a valid password.
They must also find out if they must set the remote modem for auto answer
(necessary if your modem uses Dialback as a security method).
1. If the host modem security is set up, get a password from the host
modem operator. Passwords are case-sensitive, so be sure to copy it
down correctly.
If the host modem security is set up for prompting and the host
operator enables dialback for your account, skip to Step 3.
2. For remote users with COURIER modems only. Set up security on your
modem, including an account that uses the password the host asked you
to use. Refer to Set up Your Security Account, earlier in this
appendix, for instructions.
Then assign the password as your autopass password. Enter the following
command, where n is the number of the account you set up):
AT %V=PWn <Enter>
You can check to see that you've correctly set up your autopass
password by typing the following command:
AT I10 <Enter>
Your autopass password appears in the right-hand column below FORCED
AUTOPASS.
Once the autopass password is set, enable your Courier modem<65>s Dial
Security with the following command:
ATS53.0=1 &W <Enter>
3. If Dialback is enabled at the host Courier site, set your modem to
answer the host modem when it disconnects and dials back.
To set the modem to answer the Dialback call, set DIP switch 5 OFF
and reset the modem (ATZ <Enter>).
Alternatively, type the following command:
AT S0=1 <Enter>
4. Call the host modem.
5. When the call is completed, if you want to disable auto answer, do one
of the following:
* Set DIP switch 5 ON and reset the modem (ATZ<Enter>).
* Type the following command:
AT S0=0 <Enter>
___________________________________________________________________________
REMOTE ACCESS OPERATIONS
You can set a Courier modem so that someone at a remote location can
configure your modem.
This might be helpful if you have problems making a connection with
another modem. For example, if you have trouble connecting with a
bulletin board, you can allow the bulletin board operator to dial
in to your modem and view its configuration settings. If necessary,
the bulletin board operator can send the Courier a configuration string
that will make it compatible with the bulletin board.
Another use might be for Dial Security administration when the system
administrator is unable to be at the host modem site. It might be urgent,
for example, to disable an account.
*************************
AT THE HOST COUTRIER SITE
There are two tasks required to set up remote access:
1. Set up password security.
2. Enable remote access.
************************
Set Up Password Security
You can designate two passwords for remote access security, each allowing
a different level of access to the remote user. You can assign one
password that allows viewing privileges only, whereby the host Courier's
configuration can be remotely viewed but not changed. You can assign
another password that allows both remote viewing and configuration
privileges.
Remote access passwords can be up to eight alphanumeric characters
long, and are not case-sensitive.
%Pn Use the %Pn command to assign remote privileges.
%P0 Viewing privileges only
%P1 Viewing and configuration privileges
To assign a password that allows viewing privileges only, use the command
format below:
AT%P0=[password] <Enter>
To assign a password that allows viewing and configuration privileges,
use the command format below:
AT%P1=[password] <Enter>
Disabling Password Security
If you want to disable an assigned password (and thereby disable remote
access security), use the following command format:
AT%P0= <Enter>
or
AT%P1= <Enter>
WARNING: If you disable the %P1 password, a remote user does not need
to enter a password for configuration access.
********************
Enable Remote Access
Set Register S41 for a value of 1 or greater. S41 is used to set the
number of allowable login attempts, as explained later. A setting of
zero allows no login attempts, and thus disables remote access.
AT S41=1 <Enter>
NOTE: This method will not work if your modem is attached to certain
synchronous devices. Refer to Appendix F for more information.
LED Indicator for Remote Access
The Courier's SYN status light indicator (LED) flashes to indicate when
it is in a remote access session.
************************
AT THE REMOTE MODEM SITE
Remote configuration can be performed at any time during an asynchronous
connection. The user performing remote configuration can use any modem;
it does not have to be a U.S. Robotics model.
1. Make sure the host Courier has been set for remote configuration, as
described earlier. Then establish a connection. It does not matter
which modem originates the call.
2. After a connection has been established, send the following escape
sequence:
Pause four seconds,
type four tildes: ~~~~
and
pause another four seconds.
NOTE: You can change the escape sequence character with Register S42.
The pause duration (guard time) can be modified with Register S43.
(These values are set at the host Courier modem.)
3. When the Courier begins its login sequence, the caller will see a
display similar to the following:
U.S Robotics Courier HST Dual Standard V.34 Fax Remote Session
Serial Number 000000A000000001
4. At this point, if password security is active, the caller is prompted
for the password.
Password (Ctrl-C to cancel)?.....
As described earlier in Password Security, entering the password
assigned by the %P0 command allows viewing privileges only. Entering
the password assigned by the %P1 command allows viewing and configuration
privileges. Note that there is a 3-minute time limit for entering the
password.
As mentioned earlier, if the number of unsuccessful login attempts
exceeds the set limit, the modem returns online and refuses any further
login attempts during the remainder of that connection.
When a password is accepted, the Courier indicates that it has entered
Remote Access mode and the remote prompt appears on the remote caller's
screen.
Access Granted
Remote->
5. If password security is not active (no passwords have been set or both
passwords are disabled), the Courier automatically enters Remote
Access mode and the remote prompt appears on the remote caller's
screen.
Remote->
6. Once the remote access session has been established, keep in mind that
there is a 3 minute inactivity timer. If the modem detects no activity
for 3 minutes, it aborts the remote access session and resumes a normal
online connection.
Aborting the Request for Remote Access
If you want to abort the remote access login before you have entered the
password, return online by pressing <Ctrl>-C or typing ATO <Enter>.
********************************
Remote Viewing and Configuration
Once you've gained remote access, you can communicate with the host Courier
as if you are entering commands at its attached computer. Depending on your
access privileges, you can use the regular Courier AT commands.
If you have view privileges only (with %P0), you can use any of the view
(Inquiry) commands described in Chapter 6.
If you have view and configure privileges (set with %P1), you can use any
of the modem commands, except those commands that cannot be used while
online, such as the Dial command. You can also use the remote
configuration commands explained later.
When you make remote configuration changes, the remote prompt is altered to
indicate that changes have been made. The prompt will change from:
Remote->
to
Remote+>
If you restore the original configuration (with %C1, explained next), the
original prompt is also restored (back to Remote->), indicating that the
original configuration is intact.
By default, configuration changes do not take effect until the connection
is terminated (see %Cn). However, the new configuration is immediately
reflected on the information screens (ATIn).
*****************************
Remote Configuration Commands
There are some additional commands that are only executable during a remote
access session. These commands are as follows.
%Bn Configure the Courier's serial port rate.
%B0 110 bps %B6 9600 bps
%B1 300 bps %B7 19,200 bps
%B2 600 bps %B8 38,400 bps
%B3 1200 bps %B9 57,600 bps
%B4 2400 bps %B10 115,200 bps
%B5 4800 bps
%Cn Configuration control.
%C0 Defer configuration. This is the default. Configuration
changes are deferred until the call is ended; they take effect
for ensuing connections. You do not need to enter this
command; it is the default unless you enter %C1 or %C2.
%C1 Restore configuration. Use this command to cancel any
configuration changes made during remote access, and
restore the original configuration. However, commands that
have been written to NVRAM (with &W) will not be restored to
their previous settings. Additionally, if you have forced
immediate configuration changes (with %C2), those changes
cannot be reversed with %C1.
%C2 Execute configuration. Use this command to force
configuration changes to take effect immediately,
during the current connection. We recommend against
forcing immediate configuration changes unless absolutely
necessary, as this can result in an unreliable connection
or even a loss of connection.
%Fn Configure data format.
%F0 No parity, 8 data bits.
%F1 Mark parity, 7 data bits.
%F2 Odd parity, 7 data bits.
%F3 Even parity, 7 data bits.
Password Commands
%Pn= Disables password security (n=0 or 1) when no character follows
the equal sign.
%Pn=s Specify the following password string (s) for viewing privileges
only (n = 0) or view and configuration privileges (n= 1).
%Pn? Display password n.
Command Format
When typing commands during the remote access session, no delay between
command strings is necessary. For example, you can type the following
commands without pausing after each one:
* a password: ABCDEF <Enter>
* a configuration string: AT&H1&R2&W <Enter>
* and a request for an information screen: ATI5 <Enter>
The maximum number of characters between carriage returns is 40.
Ending a Remote Access Session
One of four commands ends a remote access session.
* <Ctrl>-C aborts the login procedure.
* ATZ resets the modem and terminates the connection.
* ATH terminates the connection.
* ATO or ends the remote access session, but the modems remain online.
**********************************
Configuring Dial Security Remotely
The system administrator can configure host Courier security account
information with a Courier modem at a remote site using the procedures
described below.
NOTE: Before remote configuration is possible, the local modem's remote
access must be enabled, and a remote access password that allows viewing
and configuration privileges must be assigned. For convenience, you may
want to use your local access password as your remote access password.
Dialing In From the Remote Site
1. From the remote site, connect to the host modem using Dial Security.
Once a connection is made, follow the instructions for beginning a
remote access session as described earlier in this appendix.
2. When remote access has been granted, use the %S= command to access the
Dial Security accounts.
3. If you wish, you can view account information by typing the following
Inquiry (I) command:
AT I10 <Enter>
4. Make any configuration changes and execute them immediately by typing
the following command:
AT %C2 <Enter>
5. To end the remote session and reactivate local access security on the
host modem, reset the modem by typing:
ATZ <Enter>
WARNING: If you do not use the ATZ command to end a remote access session,
local access security will remain disabled at the host Courier site and
anyone dialing in to your modem for remote access will have access to the
I10 screen and all Security accounts.
Appendix E--Troubleshooting
You may occasionally encounter one of the problems listed here. They are
divided into three categories: Running the SDL.EXE Upgrade Program, Before
Establishing the Link, and During Data Transfer.
***********************************
Running the SDL.EXE Upgrade Program
Your modem . . .
Is indicating an error
Try running the SDL program at a lower serial port rate. If your
computer doesn<73>t have a 16550 UART, a slower serial port rate can
make all the difference.
You can also try running the program on a different PC. An
idiosyncracy of an off-brand PC or an uncommon version of DOS may
lock up the SDL program.
***************************
Before Establishing the Link
Your modem . . .
Doesn't answer the phone or go off hook to dial a number
Review your communications software manual to see what Data Terminal
Ready (DTR) operations your software requires. Then check to see if
DIP switch 1 is set correctly. Also, check to make sure your terminal
or computer is sending a DTR signal via the RS-232 interface.
Doesn't respond OK when you type AT <Enter>
1. Make sure you're typing in either upper case or lower case letters,
not a combination, and that you press the Enter key.
2. If you're using a computer, make sure it is in Terminal mode. This
is a communications software function. See Testing the Modem in
Chapter 2.
3. Check to see that your terminal or software is set to the correct
bit rate and word length (7 bits with or without a parity bit, or
8 bits and no parity). If you're using a computer, make sure your
software is set to the correct communications port.
4. Check that DIP switch 8 is ON, for command set recognition. If the
switch is OFF, power off the modem, set the switch ON, and power on
the modem again. Try typing AT <Enter> again.
5. Check that DIP switch 3 is ON, for result code display, and that
DIP switch 2 is OFF, for verbal result codes. If not, change the
switch(es) and type ATZ <Enter>. Or type whichever of these commands
is needed:
ATQ0 <Enter> (to enable the message)
ATV1 <Enter> (to display a verbal message)
6. Review your communications software manual to see what Carrier
Detect (CD) operations your software requires. Then check to see
if DIP switch 6 is set correctly.
7. A rare condition is that your terminal or computer reverses the
send/receive functions at the RS-232 interface. See your equipment
documentation.
Displays double characters
Both your modem's and software's local echo are on. You can turn your
software's local echo off. Or turn the modem's echo off by either
resetting DIP switch 4 and sending the modem the ATZ command, or by
sending the modem the ATE0 command.
Your computer . . .
Reacts as though a data link has been established, but no call has been
received
DIP switch 6 is set ON at the factory for Carrier Detect (CD) override,
but your system may require that the override be turned OFF.
Review your terminal's manual or your communications software manual to
see what CD operations are required. Then check to see if DIP switch
6 is set correctly.
When the modem is in Answer mode, it acts as though a Carriage Return has
been entered, but nothing has been typed at the keyboard
Your software may be misreading signals from the modem as it
automatically sends a Carriage Return and a Line Feed before and after
the RING and CONNECT messages. Sending the Quiet mode command, ATQ1
<Enter>, should solve the problem.
Both modems . . .
Exchange carrier signals, but fail to establish a communications link
1. If you have a fax modem, make sure it is in the correct mode, fax
or data, depending on whether the connection is to be made with a
facsimile device or a data modem. See Fax Operations in Chapter 5
for information on switching between Fax and Data modes.
2. Asynchronous operations: Check to make sure the proper bit rate,
word length, parity and number of Stop bits have been selected.
Synchronous operations: review the link instructions in Appendix F.
If you've set the modem to the correct configuration, the problem may
be with the synchronous adapter or with the system you're trying to
call.
3. Check to see that your modem is at the correct Bn setting to connect
with either an HST modem (B1 setting) or V.32 terbo modem (B0 setting).
Type ATI4 for a display of the Courier's current settings and, if
necessary, send the modem the correct setting.
4. If your modem is attempting to answer a V.32 call, you may need to
lengthen the extra V.32 answer tones. See S28 in Appendix B.
5. Depending on your model, make sure the modem at the other end of the
line is HST compatible, V.32 terbo compatible at 14.4K bps, or V.32
compatible at 9600 bps, V.22 bis-compatible at 2400 bps, Bell
212A-compatible at 1200 bps, or Bell 103-compatible at 300 bps.
These are the common signaling standards for full duplex dial-up
network transmission in the U.S.
6. Make sure your modem's connection rate setting, &Nn is correct for
the call. If the connection rate is locked at a speed (&N1-&N14)
different from the calling modem's, the Courier hangs up. The
factory setting of &N0, variable link operations, allows the two
modems to negotiate the highest possible connection rate.
7. If none of the above corrects the problem, it's likely that the
quality of the phone connection is poor and that the other modem is
missing the signals your modem is transmitting. The variable
quality of phone line connections may be due to any number of
conditions in the phone service's equipment or the current
environment. Try several calls, and if you still can't get through,
try calling another modem. If the second modem accepts your call,
the problem may lie with the modem you first tried to call.
********************
During Data Transfer
Your screen displays . . .
Only brackets
Check to make sure that both modems are set to the same bit rate, word
length, parity and number of Stop bits. If the settings are correct,
the problem may be with the phone line. Try the following measures:
1. Try placing the call again. The phone company routes even local
calls differently each time you call.
2. Try calling a different modem to see if the problem persists. The
problem may be with the modem you first tried to call.
Random or garbage characters
Check to make sure that both modems are set to the same bit rate, word
length, parity, and number of Stop bits.
If the modem is set to a fixed serial port rate (&B1) and your software
is fixed at 19.2K, 38.4K, 57.6K, or 115.2K bps, the reason may be one
of the following:
1. Your computer may not support the high rate. If this is the case,
fix your software rate at 9600 bps and disable high-speed V.32 terbo
modulation: ATS34=3 or ATS34 .0=1 .1=1.
2. If you use memory-resident programs (TSRs), they may be interfering.
Try disabling them before you run your communications software.
The same is true of disk-caching programs.
3. Check to see that your software and the modem are set for the same
kind of flow control, either hardware or software. Some
communications programs also require that you disable the kind
you are not using.
Double characters
Your modem's online local echo is on and the remote modem is also
echoing. The only way to correct this is to bring the modem back
to Command mode (wait one second without transmitting data, type
+++, wait another second). Then type the command to turn off your
online echo (ATF1 <Enter>).
If DIP switch 9 is OFF (factory setting), the modem hangs up when it
returns to Command mode, and you'll have to call again. If DIP switch
9 is ON, the modem maintains its connection. You can return it back
online by typing ATO <Enter>.
**************************
IF YOU STILL HAVE PROBLEMS
The problems described above are by far the most common ones that users
encounter. If the suggestions we've given don't clear up your difficulties,
try the following:
1. Review the manual carefully to see if you've missed something.
2. Call or visit your modem dealer. Chances are your dealer will be able
to give you the assistance you need. This is much more efficient and
time-saving than returning the modem to U.S. Robotics.
3. If your dealer can't help you, refer to the Customer Service Access
Card provided in this package. This card lists several important U. S.
Robotics numbers.
4. If you must return your modem to us, the Service Representative you
talk to will give you a Return Materials Authorization (RMA) number.
Modems without an RMA number will not be accepted.
5. If you do return the modem to us, please use the following procedures.
a. Ship the unit, postage paid, in its original container. If the
original container is not available, pack the modem carefully in a
strong box of corrugated cardboard with plenty of packing material.
b. Be sure to include your RMA number inside the package, along with
your name and address. Put your return address and your RMA number
on the shipping label as well.
c. Ship the well-packed modem to the following address.
Technical Support Department
U.S. Robotics, Inc.
8100 North McCormick Boulevard
Skokie, Illinois 60076-2999
d. Please note that U.S. Robotics will not accept packages sent COD,
so be sure to send the modem postage paid.
e. U.S. Robotics will repair your modem and return it to you via
United Parcel Service.
Appendix F--Synchronous and Dedicated Line Operations
___________________________________________________________________________
SYNCHRONOUS APPLICATIONS
Synchronous mode is required for users who need to call, or receive
calls, from a Host computer of a large network. The Host is usually
a mainframe. There are two ways the Courier can operate in synchronous
mode:
* Selecting the ITU-T standard V.25 bis protocol, which formats data in
HDLC or character-oriented frames. This method is used by mainframe
operators and synchronous terminal users.
V.25 bis acts as an interface between the mainframe and modem, sending
synchronous responses. An asynchronous device or a "dumb" terminal
is used to configure the modem before it dials out in synchronous mode.
* Dedicating a PC as a synchronous device by installing the proper
hardware and software so it can communicate with a mainframe. The modem
is configured and dials out in asynchronous mode, then switches to
synchronous mode once a connection is made.
NOTE: HST modulation is not supported for synchronous communications.
********************
GENERAL REQUIREMENTS
Courier modems in asynchronous mode adapt to many conditions of remote
asynchronous modems. But synchronous connections to a mainframe require
strict adherence to specific operating parameters. If you are operating
a terminal designed for a particular network, you probably need only set
the Courier properly before calling or answering.
NOTE: The term DTE in the following discussion means Data Terminal
Equipment, the end-to-end equipment involved in data communications.
DTE denotes your terminal or computer and the remote computer.
*********************
What You Need to Know
The network's communications management staff can supply information on
the following requirements:
* The protocol needed for your calls
* The software support needed to log into the network; for example, a
specific communications package or interface board
* The phone number, if you will be calling instead of answering
* Any restrictions about when you can call
********************
The RS-232 Interface
Transmit and Receive synchronous timing pins are required at the RS-232
interface. You'll need either pin 15 or pin 24 for Transmitter timing
signals, depending on whether the modem (pin 15) or the DTE (pin 24)
generates the signals. You'll also need pin 17, for Receiver timing
signals. If you're building your own cable, review the RS-232 Interface,
in Appendix B.
**********************
Protocol Compatibility
The devices at both ends of the link must use the same protocol. These
protocols format data into blocks or frames and add control information.
If the modem is in V.25 bis mode, the link protocol must be HDLC
(High-Level Data Link Control), or character-oriented. If the modem
is in Online Synchronous mode it may use HDLC, character-oriented, or
another protocol determined by the mainframe manufacturer.
******************************
Data Rate Synchronization (&Xn)
During synchronous operations, transmit and receive clocks at both ends
of the phone link control the precise timing of the data flow. The
communications equipment at the remote DTE and your modem and DTE must
all handle the data at the same speed.
The transmit clock timing signals setting, &Xn, determines whether the
modem or DTE will generate the timing signals. For Online synchronous
operations, the source for this setting must be the same on both systems.
See Connection Rate (%Nn, &Nn) later in this appendix.
Most Online synchronous users will require the default setting, &X0.
&X0 The Courier is the source of the Transmit clock timing signals and
sends them to your DTE over the RS-232 interface. The DTE rate will
follow the connection rates. Default.
&X1 The DTE is the source of the Transmit clock timing signals and sends
them to the Courier over the RS-232 interface. This setting is used
typically in leased line multiplexed operations. (Multiplexors divide
the phone channel so that the channel carries several calls at the
same time.)
The DTE ignores the Courier's clock timing signals and negotiates
the DTE and connection rates.
&X2 The Courier's Receiver clock is the source of the timing signals.
The signals are looped to the Transmit clock and sent to your DTE
over the RS-232 interface. This setting is only used in those
systems that require synchronization of data flowing in both directions.
**********************
V.25 BIS RREQUIREMENTS
V.25 bis is an ITU-T standard that uses the HDLC or character-oriented
protocols to format data.
Before you attempt to connect to a synchronous network, you must configure
the modem in command (asynchronous) mode by using either an asynchronous
device or dumb terminal. V.25 bis commands are used for this purpose.
The computer or terminal sends V.25 bis commands to the modem to ready
the line for synchronous transmission. Once the synchronous connection
is made and the modem is in synchronous mode, V.25 bis commands are no
longer necessary and are ignored. The modems on each end of the
connection are transparent to the host computers or terminals.
To set the modem, follow the instructions in Chapter 4, Command Set Usage.
Commands begin with a required AT prefix and end with a required Carriage
Return, which we denote with the symbol <Enter>. For example, the
following command causes the modem to set the connection rates, enable
normal result codes, enable auto answer, select HDLC as a link protocol,
and save the settings to NVRAM. Spaces have been added only for
readability.
AT &N0 %N6 X0 S0=1 &M7 &W <Enter>
Be sure that DIP switch 10 is OFF so that the modem loads the settings
you've stored in nonvolatile random access memory (NVRAM) when it
powers on. Until you customize your own settings, the settings in
NVRAM are the same as the &F1 Hardware Flow Control template.
**************************
Connection Rate (&Nn, %Nn)
There are three phases to obtaining and maintaining a connection rate
during synchronous communication.
Clock Speed Control
The first phase is in deciding where the clock speed will be determined.
(See Data Rate Synchronization, above.)
Offline Host/Modem Clock Speed
The second phase involves the data rate between the host computer or
terminal and its modem during offline mode. The %N command is used to
set the clock speed between the modem and host, but this speed is only
during offline mode, before the synchronous connection is made.
The %Nn command works in conjunction with &Xn. If the modem is set so
that it is the source of the Transmit clock timing signals
(&X0--default), the %Nn commands set the computer or terminal-to-modem
V.25 bis clock speed. If the modem is set to &X1, the computer is the
source of the Transmit clock signals.
If %Nn is set to 0 or 1, you will receive an error message, since they
are not valid values. The %Nn rates are as follows:
%N0 Reserved %N6 9600 bps (default)
%N1 Reserved %N7 12.K bps
%N2 1200 bps %N8 14.4K bps
%N3 2400 bps %N9 16.8K bps
%N4 4800 bps %N10 19.2K bps
%N5 7200 bps
Online Connection Rate
The &N command sets the data rate during the synchronous connection.
If &Nn is set for 2-10, the modem ignores the %Nn rate and follows
the &Nn rate to set the Online connection rate. The &Nn rates are
as follows:
&N0 Variable (default) &N6 9600 bps
&N1 Reserved &N7 12K bps
&N2 1200 bps &N8 14.4K bps
&N3 2400 bps &N9 16.8K bps
&N4 4800 bps (terbo-terbo only)
&N5 7200 bps &N10 19.2K bps
(terbo-terbo only)
Recommended Settings
When the connection is made and the data rate is determined, host/modem
rates may change dramatically to match the connection rate (when in
online synchronous mode, the modem is transparent on the line). To
avoid this dramatic rate switching (which can be hard on some computers),
we recommend that the modem be set with a fixed rate between the computer
or terminal and modem (%Nn) and that the connection rate (&Nn) be set to
the same rate.
*****************
Result Codes (Xn)
The Courier displays normal or extended synchronous result codes,
depending on the setting of the Xn command. By default, the modem is
set to X1 for extended result codes. To change to normal result codes,
set the modem to X0.
The normal result codes return messages such as VAL or INV (VALID or
INVALID), whereas the extended codes offer explanations--
INVPS (INVALID Parameter Syntax Error).
**************************
Automatic Answering (S0=1)
When the Courier is operating in V.25 bis mode, it ignores the DIP
switch 5 setting, which controls Auto Answer. To set the modem to
automatically answer incoming calls, set the modem to S0=1, so it
answers on the first ring. You can substitute a higher value. See
the S-Register summary in Appendix B.
Suppressing Auto Answer
To disable Auto Answer, set the modem to answer on zero rings, S0=0.
*************************************
Choosing a Synchronous Protocol (&Mn)
Once the &Xn, %Nn, &Nn, Xn, and S0 commands are configured, you must
use the &Mn command to choose the HDLC or character-oriented link
protocol so that your synchronous software can properly format its
commands.
&M6 Use the character-oriented protocol for synchronous communications.
The Courier and the remote modem must use the same eight-bit data
format. The character length must be 7 bits and either ODD or
EVEN parity (ODD is preferred), or 8 bits and NO parity.
&M7 Use the High Level Data Link Control (HDLC), an ITU-T standard
for synchronous communications. HDLC ignores parity.
**********************************
V.25 bis Commands and Result Codes
Commands
* CIC (Connect incoming call) Instructs the modem to answer an incoming
call.
* CRN (Call request using number provided )Instructs the modem to dial
the number following this command.
Example:
CRN18001234
* CRS (Call Request with memory location)Instructs the modem to dial a
number stored in memory.
Example:
CRS3
* DIC (Disregard incoming call)Instructs the modem to disregard an
incoming call--overrides auto answer for this call.
* PRNn (Program number)
Stores a number in NVRAM.
Example:
PRN3; 18001234
* RFN (Request list of forbidden numbers)Instructs the modem to list the
numbers with which the modem is unable to connect.
* RLN (Request list of stored numbers)Instructs the modem to list those
numbers previously stored in NVRAM.
Dial Options
0-9 Digits
& Flash
: Wait for dial tone
> (Greater Than) separator
< Pause
= (Equal Sign) separator
P Pulse
T Tone
. (Period) separator
- (Minus) separator
Result Codes
* SFI (Call failure indication) with optional parameters:
- CFAB (Abort call)
- CFCB (Local modem busy)
- CFET (Engaged tone)
- CFFC (Forbidden call)
- CFNS (Number not stored)
- CFNT (Answer tone not detected)
* CFRT (Ring tone)
* CNX (Connect)
* LS (List of numbers)
* LSF (List of forbidden numbers)
* LSN (List of stored numbers)
* INC (Incoming call)
* INV (Invalid) with optional parameters:
- INVMS (Message syntax error)
- INVCU (Command Unknown )
- INVPS (Parameter syntax error )
- INVPV (Parameter value error )
* VAL (Valid)
Commands and Result Codes NOT Supported
* CRI (Call request with identification number)
* PRI (Program identifier)
* RLI (Request list of identification numbers)
* RLD (List of delayed call numbers)
**********
Hanging Up
Since the modem cannot accept commands once it is connected in synchronous
mode, you cannot use the ATH (hang up) command or the +++ escape sequence.
The only way for the modem to disconnect is to drop its DTR signal. This
is normally done with software. However, if the modem is initially set
to S32=6 when it is in asynchronous mode, the modem will reset when the
voice/data switch is pressed, thus dropping DTR.
******************************
Returning to Asynchronous Mode
Once you've completed a communication session, you can switch between
synchronous and asynchronous modes by flipping DIP switch 10 OFF
(factory settings, asynchronous mode) and then ON (NVRAM settings,
synchronous mode if the modem is set to &M6 or &M7).
The modem cannot switch between synchronous and asynchronous while a call
is connected.
*******************************
ONLINE SYNCHRONOUS REQUIREMENTS
Although personal computers do not usually support synchronous
communications, they can be dedicated to do so. If you have a personal
computer you must find out what hardware and software you need before
setting the Courier for synchronous calls.
****************************
The Synchronous Adapter Card
You will probably have to purchase and install a synchronous adapter
card. These cards are multifunction boards that provide the following
functions:
* A synchronous port from the DTE to the modem
* One or more synchronous protocols. Be sure to find out which protocol
the Host mainframe requires before you purchase an adapter.
* Additional software functions. For example, you need to identify the
type of computer or terminal you are using to the mainframe software.
You will most likely also have to specify your application--that is,
identify the mainframe resources you want to use.
*****************
Setting the Modem
When the modem is set to Online Synchronous mode, it remains in command
(asynchronous) mode until it makes a synchronous connection with a remote
modem. Upon connection, the Courier enters synchronous mode and sends
synchronous timing signals to your DTE.
Because the modem will not accept commands when it is in synchronous mode,
you will have to configure it in asynchronous mode before trying to connect
to a synchronous network.
NOTE: Be sure that DIP switch 1 is OFF (factory setting). The Data
Terminal Ready (DTR) override must be OFF so that the Courier detects
when the DTE raises and lowers the DTR signal.
To set the modem, follow the instructions for issuing commands in Chapter
4, Command Set Usage. Commands begin with a required AT prefix and end
with a required Carriage Return, which we denote with the symbol <Enter>.
For example, the following command causes the modem to set the modulation,
the connection rate, and choose a timing source. Spaces have been added
only for readability.
AT B0 &N0 &X0 <Enter>
************************************
Modulation/Connection Rate (Bn, &Nn)
Use the following guidelines for your Courier type. V.Fast Class does not
support synchronous mode.
V.32 terbo modems
If the modem is connecting with another U.S. Robotics V.32 terbo modem,
set both modems to B0 and to a variable connection rate, &N0. The modems
will connect at the highest possible rate.
If the Courier V.32 terbo is to connect with a V.32 modem, set the Courier
to B0 and try a variable connection rate first, &N0. If that doesn't work,
try a fixed connection rate of &N6 (9600 bps) or &N3 (2400 bps).
Modems in HST mode
HST modulation for synchronous communications is not supported.
Dual Standard modems
Set the Dual Standard modem to B0. Try a variable connection rate
setting (&N0) first. If that doesn't work, you may have to set a fixed
connection rate, for example, &N6 (9600 bps).
NOTE: If your modem is set to a fixed rate, and the remote modem is not
set to the same rate, your modem hangs up.
*********************
Connection Rate (&Nn)
Use this command to set variable or fixed rates at the link interface. The
default is &N0, variable rate. The Courier negotiates with the remote
modem for the highest possible connection rate, depending on the
capabilities of the remote modem. If &N0 does not work, try a fixed
rate.
NOTE: The modem is not capable of connecting at 21.6K bps in synchronous
mode.
When you set the modem to a fixed rate, it will only connect if the remote
modem is operating at the same rate. If not, your modem hangs up.
The fixed rate options are as follows:
&N0 Variable rate &N6 9600 bps
&N1 Reserved &N7 12K bps
&N2 1200 bps &N8 14.4K bps
&N3 2400 bps &N9 16.8K bps
&N4 4800 bps (terbo-terbo only)
&N5 7200 bps &N10 19.2K bps (terbo-terbo only)
*******************************
Generating Clock Timing Signals
The &Xn setting specifies whether the Courier or your DTE generates the
Transmit clock timing signals for a synchronous call. Most users will
require the default setting, &X0. See Data Rate Synchronization (&Xn),
earlier in this appendix, for more information.
***********
Dialing Out
The modem's stored command feature (&ZC=s) allows you to configure the
modem for a synchronous connection and to dial out to the Host computer
by just pressing the voice/data switch. Below are our recommended
procedures.
1. If your communications software isn't running, load the program and
put the computer in Terminal mode, as described in Chapter 2.
Terminal mode allows you to send AT commands directly to the modem.
2. Using the guidelines in Chapter 4, store a command string (&ZC=s)
that configures the modem according to the Host computer's requirements.
In addition, include the &M1 command, to have the modem enter synchronous
mode, followed by the appropriate Dial string. The following is an
example:
AT &ZC = &F &X1 &M1 DT5551234 <Enter>
In the example, &F sets the modem's defaults as those of the &F0
template settings, while &X1, which specifies the computer as the
synchronous timing source, is the only non-default setting used besides
synchronous mode (&M1). Any non-default settings should follow the &F
command. The Dial command should be the last entry before the Carriage
Return.
3. Set the voice/data switch to option 9, so that the modem executes the
stored command string when you press the switch. Type the following:
ATS32 = 9 <Enter>
NOTE: If you usually use the voice/data switch for another purpose,
you can include the execute stored command option (S32 = 9) in the stored
command string. However, the total number of characters in the string
may not exceed 30.
If S32=9 is used with the stored command string, it over-writes any
other S32 option. Once the communication session is over, you will have
to reset S32 if you want to select another option.
4. Press the voice/data switch when you want to connect with the synchronous
Host computer. You need not have your communications software loaded
at the time.
5. After the call, restore the modem to asynchronous operations by
powering it off and on again.
*********
Answering
To configure the modem for Answer mode using the voice/data switch, follow
the instructions in the previous section, Dialing Out, but with these
modifications:
* Insert S0 = 1 in the stored command, Step 2. This sets the modem to
Auto Answer.
* Omit the Dial string shown in the same step (DT and phone number).
If you don't wish to use a stored command and the voice/data switch, send
the modem the appropriate configuration string, ending with &M1. The
following command adapts the dial-out command example. Note again that
all non-default settings follow the &F command.
AT &F S0=1 &X1 &M1 <Enter>
The modem responds automatically to an incoming call, enters synchronous
mode and, in this case (because it is set to &X1), waits for synchronous
timing signals from your DTE.
**********
Hanging Up
The modem remains online until the remote modem disconnects or your
software causes the DTE to drop the Data Terminal Ready signal (DTR).
The Courier sends the NO CARRIER result code if result codes are enabled,
and returns to asynchronous Command mode.
****************************
Testing and Inquiry Commands
The modem testing commands (&Tn) and inquiry commands (In) cannot be used
when the modem is operating in synchronous mode.
**********************
ENABLING REMOTE ACCESS
Because synchronous equipment cannot use AT commands to configure modems,
a special function was designed so the modem can receive AT commands
remotely. To do this, the modem must be placed in remote access mode
with the voice/data switch.
Press and hold down the voice/data switch while powering on the modem.
Pressing the switch during power-on causes the modem to perform its normal
self-test, enable Auto Answer, enable Remote Access (by changing the S41
setting to 1), and disable password security.
WARNING: If you enable remote access by pressing the voice/data switch
while powering on the modem, previously set passwords will be erased.
________________________________________________________________________
DEDICATED AND LEASED LINE OPERATIONS
The following operations apply in installations where the modem's phone
line is not part of a public-access switched telephone network. Instead,
the modem is connected to a special user-installed telephone line or a
line that is leased from the telephone company. These lines are often
referred to as dedicated (to a pair of modems) or private lines.
In both types of installation there is a continuous point-to-point
connection between two modems. No dialing of phone numbers is required.
The modems may be in either Smart or Dumb mode (determined by the position
of DIP switch 8).
*******************************************
The User-Installed or Leased Telephone Line
User-installed lines are most commonly 2-wire lines, similar to the 2-wire
lines that connect residential phones to the public switched network.
If you are leasing a line from the telephone company, request a 2-wire
line, the type of line the modem is designed to work with. If the
telephone company only makes a 4-wire line available, you'll need a
4-wire to 2-wire converter at each end of the connection. If the phone
company does not install the converters, you will have to supply them.
For optimal operations, we recommend that the physical length of these
lines not exceed 5 miles.
*****************
Setting the Modem
If the Courier is set to &L1, as described in what follows, and the
remote AT-compatible modem has a comparable setting, they automatically
connect when they are powered on. They also reconnect, without any
operator intervention, if a disturbance on the line is severe enough
to break the connection.
Set the modem as follows:
1. Set your terminal or communications software to the rate at which you
want the modems to communicate. For example, use a terminal/software
setting of 19.2K bps and, if both modems have the capability, they will
connect at 14.4K bps. The following instructions assume that you are
familiar with the guidelines on using the &B and &H commands (Chapter 3)
and the &W command (Chapter 3).
2. Send the modem the following command:
AT &B1 &S2 &H1 &L1 &W <Enter>
&B1 fixes the modem's computer interface rate at the same serial port
rate you selected when setting up your communications software. &S2
causes the modem to send a Clear to Send (CTS) signal only after it
sends the Carrier Detect (CD) signal, that is, only after it connects
with the remote modem. (See the note that follows.) &H1 enables
hardware (CTS) flow control.
&L1 forces the modems off hook at power on and enables them to
re-establish the connection should it be broken. &W writes the
settings to nonvolatile memory (NVRAM) as power-on defaults.
NOTE: We recommend using the &S2 setting to delay CTS until after
the connection is made, as a precaution. If the modems are in the
process of connecting or reconnecting, the Courier interprets any
keyboard data entry, including an accidental key stroke, as a
key-press abort, and hangs up. Delaying CTS until after carrier
detection prevents this from happening, for example, if you are typing
data to the remote modem when the modems momentarily disconnect and
begin to reconnect. However, you have to set the modem for hardware
flow control, &H1.
If your software or machine does not support Clear to Send (CTS), don't
include &S2 and &H1 in the command string as suggested above. Follow
the Transmit Data flow control (&H) guidelines in Chapter 3. But keep
in mind that if the modems fail to connect or reconnect, the reason
could be a key-press abort.
3. Set the modem to load NVRAM settings at power-on, DIP switch 10 OFF.
It does not matter if the modem is in Dumb or Smart mode (DIP switch 8).
4. Decide which modem is to be the calling modem and which the answering
modem. Set the answering modem to Auto Answer, DIP switch 5 OFF, and
the calling modem to Auto Answer suppressed, DIP switch 5 ON.
5. Power off and power on the modems. This initiates the new DIP switch
settings and loads the power-on defaults, including &L1. The modems
go off hook and establish the connection.
NOTE: If the modems cannot restore the connection and you could not set
the modem to &S2, the reason could be a key-press abort. If the problem
persists, however, you may need to call your telephone company to have
them check your line.
Appendix G--Additional Operations
CONTENTS
HST Cellular
Voice/Data (External Modems Only)
Hewlett Packard 3000 Installations
MI/MIC Operations (External Modems Only)
_______________________________________________________________________
CELLULAR OPERATIONS
This function applies to Dual Standard HSTs only. HST cellular modems
can be used to answer or originate calls, but are proprietary. They can
only connect with other U.S. Robotics Dual Standard modems with HST cellular
capabilities.
To enable cellular mode, load the &F3 template settings by typing the
following command:
AT &F3 <Enter>
To save this as your power-on/default setting, type this:
AT &F3 &W <Enter>
The &F3 command sets the serial port rate to 19,200 bps, and formats the
data for 8 bits, no parity and one stop bit. The ini-tialization string
sent to the modem by loading this template is shown below.
AT B1 X7 S10 = 30 &B1 &L2 &H1 &I0 &R2
* B1--enables HST modulation
* X7--displays extended result codes including NO DIAL TONE, RINGING, NO
ANSWER, and BUSY messages
* &B1--locks the serial port rate so that it remains higher than the
connection rate.
* S10=30--sets the modem to wait 3 seconds after loss of carrier before
hanging up.
* &L2--enables cellular mode
* &H1--enables hardware flow control
* &I0--disables software flow control
* &R2--sets the modem so it sends received data to the computer or terminal
when the Ready To Send (RTS) signal is high, only if the computer or
terminal supports RTS.
The modem uses the U.S. Robotics proprietary HST cellular protocol to make
connections. The call starts at 1200 bps, a V.42 error control connection
is negotiated, then the modem switches to 4800 bps and begins measuring the
line conditions. Depending on line conditions, the modem decreases or
increases its connection rate, to a minimum speed of 300 bps and a maximum
of 12K bps. If a connection terminates before data transfer is completed,
the system tries to re-establish the link and complete the transfer.
If a large number of blocks are being resent (shown by the ARQ LED flashing
randomly; some software displays the blocks retransmitted in the file
transfer window), you may want to reduce the packet size by doing the
following:
1. Be sure DIP switch 9 is ON so that the modem remains online if it
receives +++.
2. If DIP switch 9 is OFF, switch it to ON and reset the modem by issuing
the ATZ command.
3. Send the modem the escape sequence by typing +++ so that the
transmission is interrupted, and wait 1 second.
4. Type AT S33=1 to reduce the packet size.
5. Then type ATO so that the modem returns online and continues to transmit.
NOTE: HST cellular connections can only be made with other U.S. Robotics
modems in HST cellular mode. The modem cannot be used to place a voice or
data call to another phone or modem when it is in this mode.
__________________________________________________________________________
VOICE/DATA (EXTERNAL MODEMS ONLY)
The voice/data switch is located on the modem's front panel. While the
switch's primary function is to toggle back and forth between voice and
data communications, this feature also allows you to perform other
functions at the touch of a switch. Use Register S32 to select these
functions, as shown in Table G.1.
Additionally, the Courier modem allows you to use the voice/data switch to
set the modem for remote access if attached to certain synchronous devices.
This is described in Enabling Remote Access in Appendix F.
NOTE: Use the voice/data switch when the modem is in Command mode
(offline). If you press the switch while the modem is online, the modem
hangs up and returns a NO CARRIER result code.
**************************************************
VOICE/DATA OPERATIONS--S32=1, S32=2 or AT COMMANDS
When you install the Courier, you have the option of plugging your phone
into the second modular jack of the modem so it's available for voice calls.
You can also switch between the phone and modem during a call.
If the remote modem has handset exclusion, you can change from voice to
data and back again, with or without issuing a command.
Handset exclusion means that if the modem is using the phone line, your
phone (handset) is automatically disconnected. However, if you keep
the handset off hook, once you hang up the modem the handset takes over
the phone line and you can use voice communications again. If the remote
user does not have handset exclusion, you may not be able to switch back
to voice mode successfully once you have switched to Data mode.
The following instructions describe how to toggle voice/data communications
with the switch. This is followed by instructions for doing the same
thing with AT commands. If the remote user does not have a switch, he
or she can follow the instructions for using the appropriate AT command.
*******************************
Voice/Data Switch--S32=1, S32=2
1. Phone the other user to establish the bit rate, parity, word length
and number of Stop bits the other person's modem accepts. (Both
modems should be offline, in Command mode.)
You and the other user must also agree on which modem will go off hook
in Originate mode and which in Answer mode. The Courier is factory
set to go off hook in Originate mode, S32=1. The Answer modem should
have S32 set to 2.
NOTE: If the stored command string command has been used (&ZC=s), the
modem will default to S32=9, which executes the stored command string
when the voice/data switch is pushed.
Either party's device can be the originate or answer modem; it doesn't
matter who made the phone call. But one modem must first enter
Originate mode and the other then enter Answer mode.
2. Without hanging up the phone, press the voice/data switch.
If S32 is set to 2, Answer mode, press the voice/data switch immediately
after the remote user forces the remote modem off hook in Originate mode.
3. The other party should force the remote modem off hook in Answer mode
by pressing the switch.
If yours is the Answer modem (S32=2), the other party should press the
voice/data switch immediately before you do so.
4. If the remote modem has handset exclusion, the remote user should also
keep the phone off hook in order to switch back to voice later. If the
remote modem doesn't have handset exclusion, you can try to switch back
to voice later. Or, you both can hang up your phones as soon as the
modems go off hook.
***************************
Software Commands--ATD, ATA
If your voice/data switch is set for a function other than voice/data
operations and you don't wish to change it, use AT commands.
1. Call the other user to establish the bit rate, parity, word length and
number of Stop bits the other person's modem accepts. Determine which
modem will originate and which will answer.
2. If you are to originate the connection, type the following command:
ATD <Enter>
NOTE: Be sure the modem is not set to X2, X4, X6 or X7, or it will
return the NO DIAL TONE result code and hang up.
3. The other party must then have the remote modem go off hook in Answer
mode. The following command is used to do this:
ATA <Enter>
4. If the remote modem also has handset exclusion, leave both phones off
hook in case you wish to switch back again to voice after your data
transfer. If the remote modem doesn't have handset exclusion, switching
back to voice may not be successful. If you don't want to switch back
to voice later, hang up both phones as soon as the modems go off hook.
*************************************
ALLOWABLE VOICE/DATA AWITCH FUNCTIONS
Use Register S32 to set the voice/data switch for the function you desire.
The default is S32=1--pressing the switch forces the modem off hook in
Originate mode. Pressing the switch when you power on the modem causes
it to perform a power-on self-test. See Table G.1--S32 Functions below.
NOTE: Some of the applications listed below require some sort of
preconfiguration. Review the Chapter/Appendix referenced before using
the Voice/Data switch function.
Table G.1--S32 Functions
S32
Value Voice/Data Switch Function Related Command
0 Disabled --
1 Voice/Data--Originate Mode (Default*) ATD (Appendix G)
2 Voice/Data--Answer Mode ATA (Appendix G)
3 Redial Last Number ATDL (Chapter 4)
4 Dial Number Stored at position 0 ATDS0 (Chapter 4)
5 Auto Answer On/Off Toggle ATS0=0 or 1 (Chapter 4)
6 Reset Modem ATZ (Chapter 4)
7 Initiate Remote Digital Loopback AT&T6, S16=8 (Appendix H)
8 Busy Out Phone Line Toggle --
9 Execute Stored Command (Default*) AT&ZC=s (Chapter 4,
Appendix F, G)
* The modem is shipped from the factory set at S32=9. If a command string
has been stored (&ZC=s), the modem executes the stored command string
when the voice/data switch is pushed. If no command string is stored,
the modem still reports that S32=9, but actually behaves as if it is set
to S32=1, Originate mode.
__________________________________________________________________________
HEWLETT PACKARD INSTALLATIONS
During error control connections, the Courier recognizes the ASCII ENQ/ACK
characters exchanged between many Hewlett Packard host computers and their
terminals. The HP host sends the terminal an ENQ character at predefined
intervals, and sends no more data until the terminal responds with an ACK
character.
Courier modems manage this ENQ/ACK protocol so that communication is
speeded up, thereby enabling HP terminals to achieve high speeds on
dial-up lines. Special flow control settings, using the &I command,
are required for HP users. These settings apply to ARQ connections only
and to Courier modems set to either B0 or B1. Disregard other Courier
flow control commands.
Set the Courier to Host mode if it is attached to the host computer, or
to Terminal mode if it is attached to a terminal, as follows:
Host mode AT&I3 <Enter>
Terminal mode AT&I4 <Enter>
___________________________________________________________________________
MI/MIC OPERATIONS (EXTERNAL MODEMS ONLY)
Mode Indicate/Mode Indicate Common (MI/MIC) closure is required by some
installations whose existing hardware does the dialing. The modems do
not Auto Dial.
In these situations, the modem must be forced off hook in Originate mode.
This is done by shorting (closing) two of the pins (not Tip and Ring) in
the phone connector. The modem is then ready to go online and accept data
when it connects with the number dialed by the system equipment.
Courier modems are shipped with MI/MIC disabled, that is, for normal use.
To set the modems for MI/MIC closure, you must do two things: physically
set jumpers on the modem<65>s printed circuit board, and enable bit 5 of
Register S34 (ATS34=32 or ATS34.5=1). We recommend you then write that
setting to NVRAM as a power-on default.
Once you've set Register S34, have the system force the modem off hook
by closing the MI/MIC leads in the phone line connector. The modem's OH
(Off Hook) status light, or LED, goes on when the modem goes off hook.
***************************
SETTIING THE MI/MIC JUMPERS
You'll have to dismantle the modem case to set the two jumper switches on
the printed circuit board, as follows:
1. Power off the modem and disconnect all of its cables.
2. Turn the modem upside down. Remove the two square vinyl feet near
the back of the case, on either side of the bottom label's DIP switch
diagram. Be careful to put the vinyl feet aside, upside down, where
they won't become stuck to another object.
3. Remove the two Phillips screws located in the wells beneath the vinyl
feet.
4. Gently pry off the plastic volume slide-switch cover.
5. Raise the back end of the case bottom until it is at about a 60 degree
angle; lift it away from inside the front of the modem. Put the case
bottom aside.
6. Locate the voice/data switch at the front of the modem. Lift up and
remove the modem (printed circuit board), carefully easing the
voice/data switch out of its opening in the front panel.
7. Turn the modem rightside up and locate jumper switches J4 and J6,
8. The jumpers are black shunts that cover two out of three upright metal
contacts. As shown in the figure, set the jumpers so they cover the
two contacts on each switch that are closest to the front panel. The
third contact on each switch is exposed.
9. Replace the modem in the case top: ease the voice/data switch into
the opening in the front panel and make sure the back of the board
rests on the locator pins at the rear (from which you removed the
screws).
10. Connect the modem's RS-232, power and phone cables, in that order
(see Chapter 2). Be sure the phone cable is plugged into the jack
closest to the center of the modem--the jack represented by the wall
jack icon on the case bottom label.
CAUTION: When you power on the modem there will be potentially
hazardous voltage, particularly near the phone jacks. Do not touch
the board when the power is on.
11. Power on the modem. Try MI/MIC closure. Check to see that the Off
Hook (OH) status light goes on. If you dialed a number, listen for
an answer tone from the remote modem. Then drop the DTR signal. The
modem should go on hook and the OH status light should go off.
12. When you are sure the equipment is working correctly, disconnect the
modem's RS-232, power and phone cables, and replace the bottom of the
modem case. Ease the two nibs near the front corners into their
openings in the front of the case top, guide the rectangular slot
over the volume switch, and ease the back of the case bottom into
place. Replace the two screws, the two vinyl feet, and the volume
slide-switch cover.
***************
TROUBLESHOOTING
You may find that the modem does not respond to MI/MIC closure, which you
can monitor by observing the LED. Or the modem may fail to go back on hook
when the computer or terminal drops the Data Terminal Ready (DTR) signal.
The probable reason for either of these conditions is that your phone
equipment reverses MI/MIC polarity.
It's possible to solve this problem by reversing the modem's MI/MIC wiring.
You'll have to dismantle the modem case again and reset the two jumper
switches on the printed circuit board, as follows:
1. Lift off the jumpers from J4 and J6. Reverse the positions. That is,
on each switch, cover the center and rightmost contacts. Make sure
the jumpers cover two contacts on each switch, or you'll disable the
MI/MIC function.
2. Replace the modem in the case top: ease the voice/data switch into
the opening in the front panel and make sure the back of the board
rests on the locator pins at the rear (from which you removed the
screws).
3. Reconnect the modem's RS-232, power and phone cables, in that order.
Be sure the phone cable is plugged into the jack closest to the center
of the modem--the jack represented by the wall jack icon on the case
bottom label.
CAUTION: When you power on the modem there will be potentially
hazardous voltage, particularly near the phone jacks. Do not touch
the board when the power is on.
4. Power on the modem. Try MI/MIC closure again. Check to see that the
Off Hook (OH) status light goes on. If you dialed a number, listen for
an answer tone from the remote modem. Then drop the DTR signal. The
modem should go on hook and the OH status light should go off.
5. If closure is not working properly, review the steps in this section.
Be sure the jumper switches are in the correct positions. If you still
have problems, there may be a problem with the phone cable. Or there
may be a problem with your hardware.
6. When the equipment is working correctly, disconnect the modem's
RS-232, power and phone cables, and replace the bottom of the modem
case. Ease the two nibs near the front corners into their openings
in the front of the case top, guide the rectangular slot over the
volume switch, and ease the back of the case bottom into place.
Replace the two screws, the two vinyl feet, and the volume slide-switch
cover.
Appendix H--Modem Testing
Testing is available with the &T command or Register S16. All loopback
testing conforms to ITU-T Recommendation V.54. Earlier U.S. Robotics high
speed modems, however, did not perform the &T test repertoire.
Only one test can be performed at a given time. If you send a test
command while the modem is in test mode, you'll receive an ERROR message.
NOTE: Testing is not available when the modem is in synchronous mode:
&M1, &M6, &M7.
***************
Testing With &T
The tests supported through the &T command include analog loopback, digital
loopback and remote digital loopback. Users can key in their own data
during testing, or use the modem's internal test pattern and error detector.
In all cases, disable error control before testing. If the modem is
detecting errors and retransmitting the affected data, your results will
be invalid.
During testing, the MR status light flashes.
***********************
Ending a Test--&T0, S18
Issuing the &T0 command terminates a test. Alternatively, set Register
S18 to a specified number of seconds, for example, S18=10. When the 10
seconds are up, the modem automatically ends the test and returns to
Command mode. If the test was Analog Loopback, the &T0 command hangs up
the modem. If the test was Digital or Remote Digital Loopback, issue an
ATH command to hang up the modem, or an ATZ command to hang up the modem
and reset it to its defaults.
NOTE: If you use the S18 test timer, but in the process of testing you
issue an ATZ command, S18 resets to zero and the timer is disabled. You cannot store a value for S18 in nonvolatile memory; its power-on and reset default is always zero.
*************************
Analog Loopback--&T1, &T8
This test checks the operation of the modem's transmitter and receiver.
There are two analog loopback options. The first, &T1, involves your
typing data that you can verify at your screen.
The second option, &T8, is an internal self-test that does not involve
the keyboard or screen. It isolates the modem from the computer
interface to give you a more specific result.
NOTE: Dual Standard modems must be set to B0 (default) or tested at
2400 bps or lower to avoid HST asymmetrical modulation at higher speeds.
***
&T1
1. If you are testing an HST or Dual Standard modem, set your terminal or
software to 2400 bps.
2. The modem must be in Command mode. If you wish, set Register S18 as a
test timer, as explained earlier.
3. Send the modem the following command:
AT &M0 &T1 <Enter>
The modem disables error control, enters analog loopback (AL) mode, and
sends a CONNECT message. The MR status light flashes.
4. Type recognizable data so that you can verify it when it is looped back
to the screen.
5. End the test. If you set S18, the modem automatically stops the test
at the timeout, exits AL mode and responds OK.
If you didn't set Register S18, wait one second and type +++ to bring the
modem back to Command mode. If DIP switch 9 is OFF, the modem also
hangs up and ends the test.
If DIP switch 9 is ON, type AT&T0 to end the test. Or send either ATH
or the command that resets the modem, ATZ. The latter two commands end
the test and hang up the modem. The modem responds OK. If the modem
sends an ERROR message, you have issued an invalid command.
6. If there were no errors, reset the modem to &M4, for error control,
unless you've issued the ATZ reset command.
NOTE: If the modem is in online-command mode, that is, still connected
to a remote modem, and you send it an &T1 or &T8 command, it drops the
call, enters AL mode, sends a CONNECT result and waits for loopback
characters.
***
&T8
This AL option causes the modem to send an internal test pattern to its
transmitter and loop it back to the receiver. An internal error detector
counts any errors and, when the test is ended, sends the number of errors
or 000 (no errors) to the screen.
Since you don't type anything during this test, and the modem does not send
anything to the screen, this option verifies only the modem. If there are
no errors but your problem continues, it may be at the computer interface.
1. If you are testing an HST or Dual Standard modem, set your terminal
or software to 2400 bps.
2. The modem must be in Command mode. If you wish, set Register S18 as a
test timer, as explained earlier.
3. Send the modem the following command:
AT &M0 &T8 <Enter>
The modem disables error control and enters AL mode. The MR status
light flashes. The modem sends its internal test pattern to the
transmitter, and loops the pattern back to the receiver. You will
not see any data on your screen.
4. End the test. If you set S18, the modem automatically stops the test
at the timeout. If you didn't set Register S18, type AT&T0 to end the
test. Or use ATH or the command that resets the modem, ATZ. Both of
the latter end the test and hang up the modem.
The modem hangs up and returns a three-digit code, followed by OK. A
code of 000 indicates no errors were found. A code of 255 indicates
255 or more errors. An ERROR message indicates that you issued an
invalid command.
5. If there were no errors, reset the modem to &M4 for error control
unless you issued the ATZ command.
***
&T2
This option is reserved.
*********************
Digital Loopback--&T3
If your modem has passed the AL test, this test can help you locate
a problem with a remote modem or the telephone channel.
NOTE: This test requires the modem to establish a connection and return
to online-command mode in response to the +++ escape code. DIP switch 9
must be set ON so that the modem does not hang up on receipt of the escape
code. After you change the switch, issue ATZ to the modem to initiate
the new setting.
As with AL testing, HST and Dual Standard modems should be tested at
2400 bps or lower.
1. Set the modem to &M0, to disable error control. HST and Dual Standard
modems should be set to 2400 bps or lower to avoid asymmetrical
modulation at higher speeds. Establish a connection with the remote
modem.
2. Bring the modem back to Command mode with the +++ escape code. Then
send it the AT&T3 command. The modem enters DL mode and the MR
status light flashes.
3. The remote user should type a short message. It will be looped back
by your modem's transmitter for verification on the remote screen.
You will not see the message or any other data.
4. When the remote user has completed the test, issue the AT&T0 command
to end the test. Or send either ATH or the command that resets the
modem, ATZ. The latter two commands end the test and hang up the
modem. The modem responds OK. If the modem sends an ERROR message,
you have issued an invalid command.
5. Reset DIP switch 9 OFF if you normally use the factory default. Reset
the modem to &M4 unless you used the reset command, ATZ.
********
&T4, &T5
The &T4 option causes the modem to grant a remote modem's request for a
Remote Digital Loopback test.
The &T5 option cancels &T4, and the modem fails to recognize such a
request. This is the default so that your modem isn't subject to
another user calling and tying up your modem without your permission.
*********************************
Remote Digital Loopback--&T6, &T7
This test, like the local digital loopback test, verifies the condition of
both modems and the phone link.
The request for and granting of Remote Digital Loopback testing requires
that both modems use ITU-T V.22 standard signaling. The test must be
performed at 2400 bps or lower. If the remote modem does not have the
capability or is not set to respond (&T4), you will get an ERROR result
code.
As with Analog Loopback, there are two Remote Digital Loopback options.
If you select &T6, you send keyboard data to the modem and verify it
when it is returned over the phone lines and to your screen. If you
select &T7, the modem sends its internal test pattern and returns an
error count to your screen.
NOTE: Both test options require the modem to establish a connection and
return to online-command mode in response to the +++ escape code. DIP
switch 9 must be set ON so that the modem does not hang up on receipt
of the escape code. If necessary, set the switch ON and then issue the
ATZ command to the modem to initiate the new switch setting.
***
&T6
1. Set the software to 2400 bps or lower. Set the modem to &M0. If you
wish, set the S18 timer.
Establish a connection with the remote modem. If you haven't already
done so, arrange with the remote user to cooperate with your testing
and, if necessary, set the remote modem to acknowledge the RDL request.
For example, older U.S. Robotics high speed modems need to be set to
S16=8.
2. Bring the Modem back to Command mode with the +++ escape code. Send it
the AT&T6 command. The modem enters RDL mode and the MR status light
flashes.
3. Type a short message. It will be looped back to your modem by the
remote modem and to your screen for verification. (The remote user
will not see your data.)
4. End the test. If you set Register S18 the modem automatically ends the
test when the test timeout is reached. If you didn't set S18, type AT&T0
to end the test. Or send either ATH or the command that resets the modem,
ATZ. The latter two commands end the test and hang up the modem. The
modem responds OK. If you issue an invalid command, the modem sends an
ERROR message.
Data errors indicate a problem with the remote modem or the phone link.
If you have not performed analog loopback testing with your modem, the
problem may also lie with your modem.
5. Reset DIP switch 9 OFF unless you normally set that switch ON, and issue
ATZ to the modem to initiate the new setting. Reset the modem to &M4
unless you used the reset command, ATZ.
***
&T7
This test option causes the modem to send an internal test pattern through
the Remote Digital Loopback. An internal error detector counts any errors
and, when the test is ended, sends the number of errors or 000 (no errors)
to the screen.
You don't need to type anything during this test. The modem sends only
its final error count to your screen.
1. Set the software to 2400 bps or lower. Set the modem to &M0. If you
wish, set the S18 timer.
Establish a connection with the remote modem. If you haven't already
done so, arrange with the remote user to cooperate with your testing
and, if necessary, set the remote modem to acknowledge the RDL
request. For example, older U.S. Robotics high speed modems need to
be set to S16=8.
2. Bring the modem back to Command mode with the +++ escape code. Then
send it the AT&T7 command. The modem enters RDL mode and the MR
status light flashes.
The modem sends its internal test pattern to the remote modem, which
loops it back to your modem. You will not see the data on your screen.
3. End the test. If you set S18, the modem automatically stops the test
when the timer times out. If you didn't set Register S18, type AT&T0
to end the test. Or send either ATH or the command that resets the
modem, ATZ. The latter two commands end the test and hang up the modem.
The modem responds OK. If you issue an invalid command, the modem
sends an ERROR message.
When you terminate the test, the modem returns a three-digit code,
followed by OK. A code of 000 indicates no errors were found. A code
of 255 indicates 255 or more errors.
If you've performed an Analog Loopback and know your modem is working
properly, errors indicate a problem with either the phone connection
or the remote modem.
4. Reset DIP switch 9 OFF unless you normally operate with it ON. Issue
an ATZ command to initiate the new switch setting. Reset the modem to
&M4 unless you've sent it the ATZ reset command.
*************************
TESTING WITH REGISTER S16
Register S16 is a bit-mapped register with the following bit functions:
Bit Value Function
0 1 Analog Loopback (AL)
1 2 Dial Test
2 4 Test Pattern
3 8 Remote Digital Loopback (RDL)
NOTE: Earlier U.S. Robotics modems require bit 3 to be enabled in order
to grant RDL to a remote modem. The modem now requires its default &T4
setting instead. To perform RDL with a U.S. Robotics modem that does
not use the &T test repertoire, that modem should be set to S16=8 before
it can grant RDL testing.
****************************
Analog Loopback (AL)--S16=1D
As with the &T AL test, do not attempt this test under error control. HST
and Dual Standard modems should be tested at 2400 bps or lower, to avoid
asymmetrical modulation at higher speeds.
To use the modem's Test Pattern (S16, bit 2) instead of typing your own
data, see Test Pattern--S16=4 later in this appendix.
1. To initiate testing, type AT&M0S16=1D. The modem disables error control,
enters AL mode and sends a CONNECT result code. The MR status light
flashes.
2. Type data to the modem for the modem to transmit, loop to its receiver,
and output to the screen. An alternative is to use the Test Pattern,
described later.
3. End the test by not typing anything for one second, then typing three
pluses (+++), and waiting another second. This forces the modem back
to Command mode. If DIP switch 9 is OFF, the modem exits AL mode and
returns to Command mode. If DIP switch 9 is ON, the modem maintains
the connection when it receives the +++ escape code. Issue the ATH
command to end AL mode.
4. Reset the modem to Data mode, S16=0, and error control (&M4), or issue
the ATZ (reset) command.
****************
Dial Test--S16=2
The Dial Test is used for factory testing the frequencies of tone values.
When S-Register 16 is set to 2 and a single tone is dialed (e.g., ATD7
<Enter>), the modem continues to transmit that tone until you type another
Carriage Return.
*******************
Test Pattern--S16=4
The test pattern can be used instead of your typed data during Analog
Loopback (AL) or Remote Digital Loopback (RDL), using &T commands or S16.
The test pattern is available at all speeds. At 300 bps, the modem's
serial port rate must be fixed (&B1) and the link rate fixed at 300 bps
(&N1). At rates over 9600 bps, just set the modem for a fixed serial
port rate (&B1).
To use the test pattern during AL testing with S16, type the following
command. The test pattern is sent through the loopback.
AT&M0S16=5D
To use the test pattern during RDL testing with S16, type the following
command:
AT&M0S16=12
To use the test pattern with the &T AL or RDL tests, insert the test
pattern command, S16=4, before issuing the test command. The first of
the following commands initiates AL, the second RDL:
ATS16=4&T1
ATS16=4&T6
The test pattern alone (ATS16=4) is used for testing equipment and the
phone line. When S16 is set to 4, the modem transmits the test pattern
upon connection with a remote modem.
Ending Testing with the Test Pattern
Pressing any character key cancels all test pattern tests and hangs up the
modem. If you used Register S16, be sure to reset Register S16 to Data
mode when you reset the modem to its error control defaults, for example,
ATZ or AT&M4S16=0.
******************************
Remote Digital Loopback--S16=8
Responding Modem
The responding modem must be ready to act on the Courier's RDL request.
U.S. Robotics high speed modems should be set to &T4. If they do not
have &T testing capability, they should be set to S16=8.
Initiating Modem
1. If DIP switch 9 is OFF, set it ON so that it does not hang up on
receipt of the +++ escape code. Issue an ATZ command to initiate the
new switch setting.
2. Set the software to 2400 or 1200 bps. The ITU-T-specified RDL signals
are defined only for connections at 2400 or 1200 bps.
3. Disable error control by setting the modem to &M0. Then establish a
connection with the remote modem.
4. Bring the modem back to Command mode by sending it the escape code:
one second of no data, three pluses (+++), and another second of no
data.
5. When the OK result code appears, send the modem the following command:
ATS16=8 O
The modem enters RDL mode (S16=8), the MR status light flashes, and the
modem goes back online (O command). Then it transmits the ITU-T-defined
RDL signals, causing the remote modem to enter RDL mode.
6. Type any data at the keyboard. (Or send the test pattern.)
7. To end the test, send the modem the +++ escape code again to bring it
back to Command mode.
8. When the modem sends the OK result, reset the modem to Data mode with
the following command:
ATS16=0
The modem signals the responding modem that RDL testing is over.
Terminate the call as you normally would, and reset the modem to its
normal error control setting, &M4 or &M5.
Or, if you wish to resume data transmission with the remote modem, add
the O command to the ATS16=0 string to return the modem online. Keep in
mind, however, that error control is disabled. Because error control
is negotiated during the connection sequence, its status cannot be
changed until the modem is back on hook and in Command mode.
Appendix I--Software Upgrades
The Courier V.34 modem is software upgradable. You can download upgrades
from the USR Bulletin Board Service (BBS) to obtain maintenance fixes or
new features.
We suggest you retain a copy of the most recent upgrade on disk so you can
download it to your modem again, should the modem lose its code for any
reason.
The software download program requires DOS version 3.0 or higher and may
be run from the DOS shell under Microsoft Windows.
****************
Call the USR BBS
1. Call the USR BBS:
ATDT 708 982 5092 <Enter>
2. Unless you are running an ASCII-based communications program, answer
YES at the graphics prompt when you connect to the BBS.
3. Press Enter with each prompt until you come to the main menu.
*************************
Download the Upgrade File
1. At the command line of the main menu, type F (File) and press Enter.
Select area 5 (Courier) from the file area menu The most recent
zipped files will display.
2. Use the Enter key to scroll through the list and use the spacebar key
to highlight a file.
Scroll through the list and highlight the file named USRSDL.EXE.
Press Enter when it is highlighted to flag the file for download.
3. Press Enter to go back to the main menu.
4. At the command line on the main menu, type D and press Enter to
initiate a download.
5. Answer the download prompts according to your system requirements.
The file will be downloaded to the directory specified in your
communications software.
6. When the file transfer is complete and you are ready to leave the
BBS, type G (Goodbye) from the main menu.
******************
Upgrade your Modem
NOTE: Your modem must be turned on for the following operation.
1. At the DOS prompt of the directory where your copy of the file has been
downloaded, type USRSDL and press Enter. The zipped file will
self-extract several files onto your computer hard disk.
2. Type SDL and press Enter.
The .EXE file checks the code embedded in itself. If there is a problem,
an error message appears and the operation is terminated. If you receive
an error message, download the file again.
3. A screen appears with default COM port information.
If you want to alter the defaults, use the guidelines below.
/c=n Enter this command to select one of four predefined COM ports
on an IBM-compatible PC. Valid entries for n are 1, 2, 3, and 4.
The default is COM 2. If you change the COM port setting, a
compatible IRQ will be displayed.
/i=n Enter this command to set up a custom port. It specifies which
IRQ (interrupt request) the COM port will use to interrupt the
processor for service. Valid entries for n are 2, 3, 4, 5, and 7.
The default is IRQ 3.
/a=n Enter this command to specify a port address, where n is the
hexadecimal address of a custom port only.
/b=n Enter this command to specify the bit rate at which the COM
port will communicate with the modem. Valid entries for n are
9600, 19200, 38400, 57600, and 115200. The default is 57600 bps.
/q This command allows you to shut off most of the screen display
as the program upgrades your modem code for batch-mode execution.
You will not be prompted to accept settings.
/? This command displays a help screen.
4. A prompt asks if you want to "Download Using These Settings? (Y/N)."
Type Y if you want to continue. Type N if you want to abort the
operation.
NOTE: This is the only opportunity you will have to abort the operation.
5. Once you have accepted the settings, the software download will begin.
During this operation, the Modem Ready (MR) LED goes out.
6. When the operation has successfully completed, the "Modem reports
download successful" message displays and the MR LED lights up again.
***************
Troubleshooting
If your modem indicates an error, try running the SDL program at a lower
serial port rate. If your computer doesn<73>t have a 16550 UART, a slower
serial port rate can make all the difference.
You can also try running the program on a different PC. An idiosyncracy
of an off-brand PC or an uncommon version of DOS my hang up the SDL program.
Appendix J--Glossary
Adaptive Speed Leveling (ASL)
Courier V.32 bis and V.32 terbo modems detect improved line conditions
and shift upward again to the next higher speed. The modems at both
ends of the connection adapt independently, each detecting and adjusting
to line conditions. ASL keeps the modems online, always operating at
the highest possible speed, and constantly ensuring data integrity.
Analog Loopback
A modem self-test in which data from the keyboard is sent to the modem's
transmitter, modulated into analog form, looped back to the receiver,
demodulated into digital form, and returned to the screen for
verification.
Analog Signals
Continuous, varying waveforms such as the voice tones carried over
phone lines. Contrast with digital signals.
Answer Mode
A state in which the modem transmits at the predefined high frequency of
the communications channel and receives at the low frequency. The
transmit/receive frequencies are the reverse of the calling modem
which is in Originate mode.
Application (application program)
A computer program designed to perform a specific function, such as
a word processor or a spreadsheet.
ARQ
Automatic Repeat Request. A general term for error control protocols
which feature error detection and automatic retransmission of defective
blocks of data. See HST, MNP, and V.42.
ASCII
American Standard Code for Information Interchange. A 7-bit binary code
(0's, 1's) used to represent letters, numbers, and special characters
such as $, !, and /. Supported by almost every computer and terminal
manufacturer.
Asymmetrical Modulation
A duplex transmission technique which splits the communications channel
into one high speed channel and one slower channel. During a call under
asymmetrical modulation, the modem with the greatest amount of data to
transmit is allocated the high speed channel. The modem with less data
is allocated the slow, or back channel (450 bps). The modems dynamically
reverse the channels during a call if the volume of data transfer changes.
Asynchronous Transmission
Data transmission in which the length of time between transmitted
characters may vary.
Because the time lapses between transmitted characters are not uniform,
the receiving modem must be signaled as to when the data bits of a
character begin and when they end. The addition of Start and Stop bits
to each character serves this purpose.
Auto Answer
A feature in modems enabling them to answer incoming calls over the phone
lines without the use of a telephone receiver.
Auto Dial
A feature in modems enabling them to dial phone numbers over the phone
system without the use of a telephone transmitter.
Baud Rate
The number of discrete signal events per second occurring on a
communications channel. Although not technically accurate, baud rate is commonly used to mean bit rate.
Binary Digit
A 0 or 1, reflecting the use of a binary numbering system (only two
digits). Used because the computer recognizes either of two states,
OFF or ON. Shortened form of binary digit is bit.
Bisync
Binary Synchronous Control. An earlier protocol developed by IBM for
software applications and communicating devices operating in synchronous
environments. The protocol defines operations at the link level of
communications, for example, the format of data frames exchanged between
modems over a phone line. See Protocol, HDLC, SDLC.
Bit Rate
The number of binary digits, or bits, transmitted per second (bps).
Communications channels using telephone channel modems are established
at set bit rates, commonly 300, 1200, 2400, 4800, 9600, and 14400.
BPS
The bits (binary digits) per second rate.
Buffer
A memory area used as temporary storage during input and output
operations. An example is the modem's command buffer. Another is the
Transmit Data flow control buffer used for flow control and to store
copies of transmitted frames until they are positively acknowledged by
the receiving modem.
Byte
A group of binary digits stored and operated upon as a unit. A byte may
have a coded value equal to a character in the ASCII code (letters,
numbers), or have some other value meaningful to the computer. In
user documentation, the term usually refers to 8-bit units or characters.
1 kilobyte (K) is equal to 1,024 bytes or characters; 64K indicates
65,536 bytes or characters.
Call Indicate
A call originating tone defined by ITU-T recommendation V.8.
Carrier
A continuous frequency capable of being either modulated or impressed
with another information-carrying signal. Carriers are generated and
maintained by modems via the transmission lines of the telephone
companies.
CCITT
Formerly, an international organization that defined standards for
telegraphic and telephone equipment. It has been incorporated into
its parent organization, International Telecommunication Union (ITU).
Telecommunication standards are now covered under Telecommunications
Standards Sector (TSS). ITU-T replaces CCITT. For example, the
Bell 212A standard for 1200 bps communication in North America was
referred to as CCITT V.22. It is now referred to as ITU-T V.22.
Character
A representation, coded in binary digits, of a letter, number, or other
symbol.
Characters Per Second
A data transfer rate generally estimated from the bit rate and the
character length.
For example, at 2400 bps, 8-bit characters with Start and Stop bits
(for a total of ten bits per character) will be transmitted at a rate
of approximately 240 characters per second (cps). Some protocols,
such as USR-HST and MNP, employ advanced techniques such as longer
transmission frames and data compression to increase cps.
Class 1/EIA-578
An American standard used between facsimile application programs and
facsimile modems for sending and receiving Class 1 faxes.
Class 2.0/EIA-592
An American standard used between facsimile application programs and
facsimile modems for sending and receiving Class 2.0 faxes.
Cyclic Redundancy Checking (CRC)
An error-detection technique consisting of a cyclic algorithm performed
on each block or frame of data by both sending and receiving modems.
The sending modem inserts the results of its computation in each data
block in the form of a CRC code. The receiving modem compares its
results with the received CRC code and responds with either a positive
or negative acknowledgment. In the ARQ protocol implemented in U.S.
Robotics high speed modems, the receiving modem accepts no more data
until a defective block is received correctly.
Data Communications
A type of communications in which computers and terminals are able to
exchange data over an electronic medium.
Data Compression
When the transmitting modem detects redundant units of data, it recodes
them into shorter units of fewer bits. The receiving modem then
decompresses the redundant data units before passing them to the
receiving computer.
Data Compression Table
A table of values assigned for each character during a call under data
compression. Default values in the table are continually altered and
built during each call: the longer the table, the more efficient
throughput gained.
If a destructive Break is sent during a call (see the &Y command),
causing the modems to reset the compression tables, you can expect
diminished throughput.
Data Mode
The mode in which the fax modem is capable of sending and receiving
data files. A standard modem without fax capabilities is always in
Data mode.
DCE
Data Communication (or Circuit-Terminating) Equipment. In this manual,
the term applies to dial-up modems that establish and control the data
link via the telephone network.
Dedicated Line
A user-installed telephone line used to connect a specified number of
computers or terminals within a limited area, for example, one building.
The line is a cable rather than a public-access telephone line. The
communications channel may also be referred to as nonswitched because
calls do not go through telephone company switching equipment.
Default
Any setting assumed, at startup or reset, by the computer's software
and attached devices, and operational until changed by the user.
Digital Loopback
A test that checks the modem's RS-232 interface and the cable that
connects the terminal or computer and the modem. The modem receives
data (in the form of digital signals) from the computer or terminal,
and immediately returns the data to the screen for verification.
Digital Signals
Discrete, uniform signals. In this manual, the term refers to the
binary digits 0 and 1.
Duplex
Indicates a communications channel capable of carrying signals in both
directions. See Half Duplex, Full Duplex.
EIA
Electronic Industries Association, which defines electronic standards in
the U.S.
Equalization
A compensation circuit designed into modems to counteract certain
distortions introduced by the telephone channel. Two types are used:
fixed (compromise) equalizers and those that adapt to channel conditions.
U.S. Robotics high speed modems use adaptive equalization.
Error Control
Various techniques which check the reliability of characters (parity) or
blocks of data. V.42, MNP and HST error control protocols use error
detection (CRC) and retransmission of errored frames (ARQ).
Facsimile
A method for transmitting the image on a printed page from one point to
another. Commonly referred to as Fax.
Fax Mode
The mode in which the fax modem is capable of sending and receiving files
in a facsimile format.
Flash ROM
Read Only Memory that can be erased and reprogrammed.
Flow Control
A mechanism that compensates for differences in the flow of data input
to and output from a modem or other device.
Frame
A data communications term for a block of data with header and trailer
information attached. The added information usually includes a frame
number, block size data, error-check codes, and Start/End indicators.
Full Duplex
Signal flow in both directions at the same time. In microcomputer
communications, may refer to the suppression of the online Local Echo.
Half Duplex
Signal flow in both directions, but only one way at a time. In
microcomputer communications, may refer to activation of the online
Local Echo, which causes the modem to send a copy of the transmitted
data to the screen of the sending computer.
HDLC
High Level Data Link Control. A standard protocol developed by the
International Standards Organization for software applications and
communicating devices operating in synchronous environments. The
protocol defines operations at the link level of communications,
for example, the format of data frames exchanged between modems over
a phone line. See Bisync, Protocol, SDLC.
HST
High Speed Technology, U.S. Robotics' proprietary signaling scheme,
design and error control protocol for high-speed modems. HST
incorporates trellis-coded modulation, for greater immunity from
variable phone line conditions, and asymmetrical modulation for more
efficient use of the phone channel at speeds of 4800 bps and above. HST
also incorporates MNP-compatible error control procedures adapted to
asymmetrical modulation.
Hz
Hertz, a frequency measurement unit used internationally to indicate
one cycle per second.
ITU-T
International Telecommunication Union-Telecommunication sector.
Formerly referred to as CCITT. An international organization that
defines standards for telegraphic and telephone equipment. For example,
the Bell 212A standard for 1200 bps communication in North America is
observed internationally as ITU-T V.22. For 2400 bps communication,
most U.S. manufacturers observe V.22 bis.
LAPM
Link Access Procedure for Modems, an error control protocol incorporated
in ITU-T Recommendation V.42. Like the MNP and HST protocols, LAPM
uses cyclic redundancy checking (CRC) and retransmission of corrupted
data (ARQ) to ensure data reliability.
Local Echo
A modem feature that enables the modem to send copies of keyboard
commands and transmitted data to the screen. When the modem is in
Command mode (not online to another system) the local echo is invoked
through the ATE1 command. The command causes the modem to display your
typed commands. When the modem is online to another system, the local
echo is invoked through the ATF0 command. This command causes the
modem to display the data it transmits to the remote system.
MI/MIC
Mode Indicate/Mode Indicate Common, also called Forced or Manual
Originate. Provided for installations where other equipment, rather
than the modem, does the dialing. In such installations, the modem
operates in Dumb mode (no Auto Dial capability), yet must go off
hook in Originate mode to connect with answering modems. See MI/MIC
Closure in Appendix G.
MNP
Microcom Networking Protocol, an asynchronous error control protocol
developed by Microcom, Inc. and now in the public domain. The protocol
ensures error-free transmission through error detection (CRC) and
retransmission of errored frames. U.S. Robotics modems use MNP
Levels 1-4 and Level 5 data compression. MNP Levels 1-4 have been
incorporated into ITU-T Recommendation V.42. Compare HST.
Modem
A device that transmits/receives computer data through a communications
channel such as radio or telephone lines. The Courier is a telephone
channel modem that modulates, or transforms, digital signals from a
computer into the analog form that can be carried successfully on a
phone line. It also demodulates signals received from the phone line
back to digital signals before passing them to the receiving computer.
Nonvolatile Memory (NVRAM)
User-programmable random access memory whose data is retained when
modem power is turned off. Used in Courier modems to store a
user-defined default configuration loaded into random access memory
(RAM) at power on.
OFF/ON Hook
Modem operations which are the equivalent of manually lifting a
phone receiver (taking it off hook) and replacing it (going on hook).
Online Fallback
A feature that allows high speed error-control modems to monitor line
quality and fall back to the next lower speed if line quality degrades.
The modems fall forward as line quality improves.
Originate Mode
A state in which the modem transmits at the predefined low frequency
of the communications channel and receives at the high frequency. The
transmit/receive frequencies are the reverse of the called modem which
is in Answer mode.
Parallel Transmission
The transfer of data characters using parallel electrical paths for
each bit of the character, for example, 8 paths for 8-bit characters.
Data is stored in computers in parallel form, but may be converted to
serial form for certain operations. See Serial Transmission.
Parity
An error-detection method that checks the validity of a transmitted
character. Character checking has been surpassed by more reliable
and efficient forms of block-checking, including Xmodem-type protocols
and the ARQ protocol implemented in Courier modems.
The same type of parity must be used by two communicating computers,
or both may omit parity. When parity is used, a parity bit is added
to each transmitted character. The bit's value is 0 or 1, to make the
total number of 1's in the character even or odd, depending on which
type of parity is used.
Protocol
A system of rules and procedures governing communications between two
or more devices. Protocols vary, but communicating devices must
follow the same protocol in order to exchange data. The format of
the data, readiness to receive or send, error detection and error
correction are some of the operations that may be defined in protocols.
RAM
Random Access Memory. Memory that is available for use when the modem
is turned on, but that clears of all information when the power is
turned off. The modem's RAM holds the current operational settings,
a flow control buffer, and a command buffer.
Remote Access
A feature that allows a remotely-located user to view the Courier's
configuration screens and change the Courier's configuration. Password
protection is available.
Remote Digital Loopback
A test that checks the phone link and a remote modem's transmitter and
receiver. Data entered from the keyboard is transmitted from the
initiating modem, received by the remote modem's receiver, looped
through its transmitter, and returned to the local screen for
verification.
Remote Echo
A copy of the data received by the remote system, returned to the
sending system and displayed on the screen. Remote echoing is a
function of the remote system.
ROM
Read Only Memory. Permanent memory, not user-programmable. The
Courier's factory settings are stored in ROM and can be read (loaded)
into RAM as an operational configuration if DIP switch S10 is ON at
power on.
Serial Transmission
The transfer of data characters one bit at a time, sequentially, using
a single electrical path. See Parallel Transmission.
Start/Stop Bits
The signaling bits attached to a character before the character is
transmitted during Asynchronous Transmission.
SDLC
Synchronous Data Link Control. A protocol developed by IBM for software
applications and communicating devices operating in IBM's Systems
Network Architecture (SNA). The protocol defines operations at the
link level of communications, for example, the format of data frames
exchanged between modems over a phone line. See Bisync, Protocol, HDLC.
Synchronous Transmission
A form of transmission in which blocks of data are sent at strictly
timed intervals. Because the timing is uniform, no Start or Stop
bits are required. Compare Asynchronous Transmission.
Some mainframes only support synchronous communications unless their
owners have installed a synchronous adapter and appropriate software.
Terminal
A device whose keyboard and display are used for sending and receiving
data over a communications link. Differs from a microcomputer in that
it has no internal processing capabilities. Used to enter data into
or retrieve processed data from a system or network.
Terminal Mode
An operational mode required for microcomputers to transmit data. In
Terminal mode the computer acts as if it were a standard terminal such
as a teletypewriter, rather than a data processor. Keyboard entries
go directly to the modem, whether the entry is a modem command or data
to be transmitted over the phone lines. Received data is output
directly to the screen. The more popular communications software
products control Terminal mode as well as enable more complex
operations, including file transmission and saving received files.
Throughput
The amount of actual user data transmitted per second without the
overhead of protocol information such as Start and Stop bits or frame
headers and trailers. Compare characters per second.
Transmission Rate
Same as Bit Rate.
V.17
An ITU-T standard for facsimile operations that specifies modulation
at 14.4K bps, with fallback to 12K bps.
V.21--Fax
An ITU-T standard for facsimile operations at 300 bps. U.S. Robotics
or compatible fax devices then transmit or receive at higher speeds.
V.21--Modem
An ITU-T standard for modem communications at 300 bps. Modems made in
the U.S. or Canada follow the Bell 103 standard. However, the modem
can be set to answer V.21 calls from overseas.
V.22
A ITU-T standard for modem communications at 1200 bps, compatible with
the Bell 212A standard observed in the U.S. and Canada.
V.22 bis
An ITU-T standard for modem communications at 2400 bps. The standard
includes an automatic link negotiation fallback to 1200 bps and
compatibility with Bell 212A/V.22 modems.
V.23
An ITU-T standard for modem communications at 1200 bps with a 75 bps
back channel. Used in the U.K.
V.25
An ITU-T standard for modem communications. Among other things, V.25
specifies an answer tone different from the Bell answer tone. All U.S.
Robotics modems can be set with the B0 command so that they use the
V.25 2100 Hz tone when answering overseas calls.
V.25 bis
An ITU-T standard for synchronous communications between the mainframe
or host and the modem using the HDLC or character-oriented protocol.
Modulation depends on the serial port rate and setting of the
transmitting clock source, &X.
V.27 ter
An ITU-T standard for facsimile operations that specifies modulation
at 4800 bps, with fallback to 2400 bps.
V.29
An ITU-T standard for facsimile operations that specifies modulation
at 9600 bps, with fallback to 7200 bps.
V.32
An ITU-T standard for modem communications at 9600 bps and 4800 bps.
V.32 modems fall back to 4800 bps when line quality is impaired, and
fall forward again to 9600 bps when line quality improves.
V.32 bis
An ITU-T standard that extends the V.32 connection range: 4800, 7200,
9600, 12K and 14.4K bps. V.32 bis modems fall back to the next lower
speed when line quality is impaired, and fall back further as necessary.
They fall forward to the next higher speed when line quality improves.
V.32 terbo
Modulation scheme that extends the V.32 connection range: 4800, 7200,
9600, 12K, 14.4K, 16.8K, 19.2K, and 21.6K bps. V.32 terbo modems fall
back to the next lower speed when line quality is impaired, and fall
back further as necessary. They fall forward to the next higher speed
when line quality improves.
V.34
An ITU-T standard that allows data rates as high as 28.8K bps.
V.42
An ITU-T standard for modem communications that defines a two-stage
process of detection for LAPM error control.
V.42 bis
An extension of ITU-T V.42 that defines a specific data compression
scheme for use with V.42 error control.
V.8
ITU-T recommendation that defines procedures for starting and ending
sessions of data transmission.
V.Fast Class (V.FC)
Proprietary modulation scheme developed by Rockwell International for
data communication speeds up to 28.8K bps.
Word Length
The number of bits in a data character without parity, start or stop
bits.
Xmodem
The first of a family of error control software protocols used to
transfer files between modems. These protocols are in the public
domain and are available from many bulletin board services.
XON/XOFF
Standard ASCII control characters used to tell an intelligent device
to stop/resume transmitting data. In most systems typing <Ctrl>-S sends
the XOFF character. Some devices, including the Courier, understand
<Ctrl>-Q as XON; others interpret the pressing of any key after
<Ctrl>-S as XON.
Appendix K--Tecnical Specifications
Your modem uses multiple standard modulation protocols and is also
compatible with many nonstandard schemes.
V.34
28.8K, 26.4K, 24K, 21.6K, 19.2K, 16.8K, 14.4K, 12K, 9600, 7200,
4800, and 2400 bps asynchronous Trellis Coded Modulation (TCM)
V.Fast Class (V.FC)
28.8K, 26.4K, 24K, 21.6K, 19.2K, 16.8K, 14.4K bps asynchronous
Trellis Coded Modulation (TCM)
U.S. Robotics V.32 terbo
21.6K, 19.2K, 16.8K, 14.4K. 12K, 9600, 7200 bps asynchronous, 19.2K,
16.8K, 14.4K. 12K, 9600, 7200 bps synchronous, Trellis Coded
Modulation (TCM)
4800 bps, synchronous/asynchronous, Quadrature Amplitude Modulation
(QAM)
U.S. Robotics High Speed Technology (HST)
16.8K, 14.4K, 12K, 9600, 7200 bps, asynchronous,
asymmetrical, 450 bps back channel with automatic handshake
adjustment to 300 bps, Trellis Coded Modulation (TCM), Quadrature
Amplitude Modulation (QAM)
4800 bps, asynchronous, asymmetrical, 450 bps back
channel with automatic handshake adjustment to 300 bps, Quadrature
Amplitude Modulation (QAM)
ITU-T V.32 bis
14.4K. 12K, 9600, 7200 bps, synchronous/asynchronous, Trellis Coded
Modulation (TCM)
4800 bps, synchronous/asynchronous, Quadrature Amplitude Modulation
(QAM)
Additional Compatibility Features
ITU-T V.32, 9600 bps, synchronous, asynchronous, Trellis Coded Modulation
(TCM); 4800 bps, synchronous, asynchronous, Quadrature Amplitude
Modulation (QAM)
ITU-T V.25 2100 Hz tone
ITU-T V.23, 1200 bps, asymmetrical (1200/75 bps), Frequency Shift
Keying (FSK)
ITU-T V.22 bis, 2400 bps, synchronous/asynchronous, Quadrature Amplitude
Modulation (QAM)
ITU-T V.22, 1200 bps, synchronous/asynchronous, Differential Phase
Shift Keying (DPSK)
Bell 212A, 1200 bps, synchronous/asynchronous, Differential Phase
Shift Keying (DPSK)
Bell 103, 300 bps, asynchronous, Frequency Shift Keying (FSK)
ITU-T V.21, 300 bps, asynchronous, Frequency Shift Keying (FSK)
Error Control Standards
ITU-T V.42 error control protocol at 14.4K, 12K, 9600, 7200, 4800 bps
(V.32 bis mode) and at 2400/1200 bps
U.S. Robotics HST error control protocol, asymmetrical mode, at 16.8K,
14.4K, 12K, 9600, 7200, 4800 bps, 450/300 bps back channel
Microcom Networking Protocol (MNP) error control protocol, Levels 2-4
at 14.4K, 12K, 9600, 7200, 4800 bps (V.32 bis mode) and at 2400/1200 bps
Data Compression Protocols
ITU-T V.42 bis data compression (all modes and speeds of 1200 bps and
higher)
Microcom Networking Protocol (MNP) Level 5 data compression (all modes
and speeds of 1200 bps and higher)
Fax Standards
The Courier modem provides Group III-compatibility when combined with
Class 1 or Class 2.0 fax software. In addition, the modem adheres to
the following standards.
TIA/EIA-578 Service Class 1 Asynchronous Facsimile DCE Control
Standard
TIA/EIA-592 Service Class 2.0 Asynchronous Facsimile
DCE Control Standard
ITU-T V.17 14.4K/12K bps
ITU-T V.29 9600/7200 bps
ITU-T V.27 ter 4800/2400 bps
ITU-T V.21 300 bps
Serial Port Rates
115.2K, 57.6K, 38.4K, 19.2K, 9600, 4800, 2400, 1200, 300 bps
Adaptive Speed Leveling
21.6K, 19.2K, 16.8K, 14.4K, 12K, 9600, 7200, 4800 bps
Phone Line Interface
RJ11 phone jacks
Communications Channel
Full/half duplex on 2-wire dial-up, dedicated, or leased phone lines;
demand-driven high speed channel turnaround in HST mode; symmetrical
speeds in V.32 bis mode
Operational Modes
Synchronous/Asynchronous, Auto Dial/Answer, Manual Originate/Answer,
Smart/Dumb mode, Auto Dial/Auto Answer, Auto Answer only, Forced
Originate (MI/MIC)
Fax Modems: The above modes plus fax mode
Dialing
Dialing Rotary (pulse 0-9), Tone (DTMF 0-9, #, *), a-z when in Quote
(") Mode
Data Format
Binary, serial; defaults to 8-bit word length, no parity, and 1 stop bit
Word Parity Stop
Length (1 Bit) Bits
7 Even, Odd 1
Mark, Space
7 None 2
8 None 1
Front Panel status lights
HS High Speed (above 2400 bps)
AA Auto Answer/Answer
CD Carrier Detect
OH Off Hook
RD Received Data
SD Send Data
TR Terminal Ready (DTR)
MR Modem Ready/Test mode
RS Request to Send
CS Clear to Send
SYN Synchronous mode
ARQ/ Error control connection established
FAX Modem in Fax mode
Flow Control Buffers
Transmit Buffer
Error control: 3.25k bytes
Non-Error control: 1.5k bytes, 128-byte option
Receive Buffer: 2K bytes
Command Buffer
60 characters, exclusive of AT prefix, Carriage Return and spaces
Test Options
Analog loopback with test pattern
Remote digital loopback
Digital loopback
Test pattern
Dial test
Call Progress Codes
FAX
DATA
NO DIAL TONE
BUSY
NO ANSWER
RINGING
VOICE
Failed Call Timeout
60-sec. default, programmable 2-255 sec.
Answer Tone Timeout
60 sec.
Fax Service Class 1 Commands
+FCLASS=n (0,1) Class identification and control
+FTS=n (0,255) Stop transmission and pause, 10ms.
+FRS=n (0,255) Wait for silence, 10 ms.
+FTM=n (3,24,48,72,73,74,96,121,122,145,146)
Transmit data with carrier
+FRM=n (3,24,48,72,73,74,96,121,122,145,146)
Receive data with carrier
+FTH=n (3,24,48,72,73,74,96,121,122,145,146)
Transmit HDLC data with carrier
+FRH=n (3,24,48,72,73,74,96,121,122,145,146)
Receive HDLC data with carrier
FAX service class 2.0 commands
Class 2.0 fax commands are too numerous to be listed here. For
information on Class 2.0 technical specifications, contact Global
Engineering Documents, at 1-800-854-7179. The document that covers
this information is:
ANSI/EIA/TIA-592-1993 (EIA-592)
Asynchronous Facsimile DCE Control Standard
May, 1993
Optional Class 2.0 FAX commands supported
U.S. Robotics implements the following optional Class 2.0 fax commands:
+FNS=0,1 Pass-through non-Standard negotiation byte string
+FCR=0,1 Capability to receive
+FAA=0,1 Adaptive Answer mode
+FCT=0-255 sec. Phase C Timeout
+FHS=0-255 Hangup Status Code, read only
+FMS=0-3 Minimum Phase C Speed
+FBS?=500,100 Buffer size, read only
V.25 bis Synchronous Commands and Result Codes
Commands: Connect incoming call (CIC); Call request using number
provided (CRN); Call Request with memory location (CRS); Disregard
incoming call (DIC); Program number (PRNn); Request list of forbidden
numbers (RFN); Request list of stored numbers (RLN).
Dial options: 0-9 & : > < = P T);
Result Codes: Call failure indication (CFI) with optional parameters:
Abort call (CFAB); local modem busy (CFCB); Engaged tone (CFET);
Forbidden call (CFFC); Number not stored (CFNS); Answer tone not
detected (CFNT); Ring tone (CFRT); Connect (CNX); List of numbers
(LS); List of forbidden numbers (LSF); List of stored numbers (LSN);
Incoming call (INC); Invalid (INV) with optional parameters: Message
syntax error (INVMS); Command Unknown (INVCU); Parameter syntax error
(INVPS); Parameter value error (INVPV); Valid (VAL).
Commands and Result Codes not supported: Call request with
identification number (CRI); Program identifier (PRI); Request list of
identification numbers (RLI); List of delayed call numbers (RLD).
Answer Tone Detector
2200-2300 Hz
Loss of Carrier (Disconnect Timer)
0.7-sec. default, programmable 0.2-25.5 sec.
Equalization
Adaptive
Transmitter Carrier Frequencies
V.34
Originate Mode: 1800 Hz
Answer Mode: 1800 Hz
Originate Mode: 1829 Hz
Answer Mode: 1829 Hz
Originate Mode: 1867 Hz
Answer Mode: 1867 Hz
Originate Mode: 1920 Hz
Answer Mode: 1920 Hz
Originate Mode: 1959 Hz
Answer Mode: 1959 Hz
Originate Mode: 2000 Hz
Answer Mode: 2000 Hz
V.Fast Class
Originate Mode: 1800 Hz
Answer Mode: 1800 Hz
Originate Mode: 1875 Hz
Answer Mode: 1875 Hz
Originate Mode: 1920 Hz
Answer Mode: 1920 Hz
USR-V.32 terbo/V.32 bis/V.32
Originate Mode: 1800 Hz
Answer Mode: 1800 Hz
USR-HST, 450 bps back channel
Originate Mode: 375 Hz
Answer Mode: 1800 Hz
USR-HST, 300 bps back channel
Originate Mode: 350 Hz
Answer Mode: 1800 Hz
V.23
Originate Mode:
Mark: 390 Hz
Space: 450 Hz
Answer Mode:
Mark: 1300 Hz
Space: 2100 Hz
V.22 bis, V.22, Bell 212A
Originate Mode: 1200 Hz
Answer Mode: 2400 Hz
Bell 103
Originate Mode:
Mark: 1270 Hz
Space: 1070 Hz
Answer Mode:
Mark: 2225 Hz
Space: 2025 Hz
V.21
Originate Mode:
Mark: 980 Hz
Space: 1180 Hz
Answer Mode:
Mark: 1650 Hz
Space: 1850 Hz
Receiver Carrier Frequencies
V.34
Originate Mode: 1800 Hz
Answer Mode: 1800 Hz
Originate Mode: 1829 Hz
Answer Mode: 1829 Hz
Originate Mode: 1867 Hz
Answer Mode: 1867 Hz
Originate Mode: 1920 Hz
Answer Mode: 1920 Hz
Originate Mode: 1959 Hz
Answer Mode: 1959 Hz
Originate Mode: 2000 Hz
Answer Mode: 2000 Hz
V.Fast Class
Originate Mode: 1800 Hz
Answer Mode: 1800 Hz
Originate Mode: 1875 Hz
Answer Mode: 1875 Hz
Originate Mode: 1920 Hz
Answer Mode: 1920 Hz
USR-V.32 terbo/V.32 bis/V.32
Originate Mode: 1800 Hz
Answer Mode: 1800 Hz
USR-V.32 terbo/V.32 bis/V.32
Originate Mode: 1800 Hz
Answer Mode: 1800 Hz
USR-HST, 450 bps back channel
Originate Mode: 1800 Hz
Answer Mode: 375 Hz
USR-HST, 300 bps back channel
Originate Mode: 1800 Hz
Answer Mode: 350 Hz
V.23
Originate Mode:
Mark: 1300 Hz
Space: 2100 Hz
Answer Mode:
Mark: 390 Hz
Space: 450 Hz
V.22 bis, V.22, Bell 212A
Originate Mode: 2400 Hz
Answer Mode: 1200 Hz
Bell 103
Originate Mode:
Mark: 2225 Hz
Space: 2025 Hz
Answer Mode:
Mark: 1270 Hz
Space: 1070 Hz
V.21
Originate Mode:
Mark: 1650 Hz
Space: 1850 Hz
Answer Mode:
Mark: 980 Hz
Space: 1180 Hz
Receive Sensitivity
- 44 dBm + 2 dBm
Transmit Level
- 9 dBm maximum
Transmitter Frequency Tolerance
.01%
Certification
FCC Part 68 and Part 15, Class B Domestic; IC (Canada), UL listed
Power Consumption
5 watts
Size
6.375 x 10.3 x 1.337 inches