USRobotics COURIER User Manual

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COURIER

HIGH SPEED MODEM

Courier V.34 Dual Standard Fax

USER MANUAL

COURIER HIGH SPEED MODEMS

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

ii How to Use This Manual

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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.

How to Use This Manual iii

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.

COURIER HIGH SPEED MODEMS

TABLE OF CONTENTS

How to Use this Manual ii Table of Contents v Limited Warranty ix FCC Registration Numbers x IC (Industry Canada) x Connecting to the Telephone Company x Radio and Television Interference x For Canadian Modem Users xi

PART I. INSTALLATION AND OPERATION

Chapter 1Features and Compatibility

Introduction 1-1

Features 1-1

Compatibility 1-6

Fax Standards 1-7 Other Compatibility Features 1-7

Chapter 2External Modem Set-Up

Switches on the Modem 2-1 Front Panel Indicators on the Modem 2-2 Package Components 2-2 What You Need 2-2

An RS-232 Cable 2-2 Communications Software. . . 2-3 Telephone Adapter. . . 2-3

You Should. . . 2-3

Refer to Appendix F. . . 2-3 Refer to Appendix G. . . 2-4

Installing the Modem 2-4 Testing the Installation 2-6

Chapter 3Internal Modem Setup

Package Components 3-1 What You Need 3-1

Communications Software. . . 3-1 A Telephone Adapter 3-2

You Should. . . 3-2

Refer to Appendix F. . . 3-2 Refer to Appendix G. . . 3-2

Before Installing the Modem 3-2

Select a Serial Port 3-3 Select an Interrupt Request (IRQ) 3-4

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Reset the Jumpers 3-5

Set DIP Switches 3-6 Installing the Modem 3-6 Testing the Installation 3-8

Chapter 4Data Mode Command Summary

Command Set Usage 4-1 Basic Commands 4-3 Dialing/Answering 4-4

Dialing 4-4

Dial Options 4-4

Cancel Dialing 4-6

Store Phone Numbers 4-7

Redialing 4-7

Answer Mode 4-8

Hanging Up 4-9 Setting/Using Defaults 4-11

Customizing NVRAM 4-12

Resetting the Modem 4-13 Configuration 4-13

Echo/Speaker 4-13

Result Codes 4-14

Additional Result Code Sets 4-17

Modulation 4-19

Error Control/Data Compression 4-19

Data Rates 4-21

RS-232 Signal Operations 4-23

Flow Control 4-24 S-Registers 4-29 Inquiry and Help 4-30 Testing 4-30 International Calls (&Gn, &Pn) 4-30 Miscellaneous Commands 4-31

Chapter 5Fax Operations and Call Detection

Fax Operations 5-1 Notes to Programmers 5-3 Call Detection 5-4

Chapter 6Queries and Help Screens

User Inquiries (In) 6-1 S-Register Query (Sr?) 6-7 Phone Number Query (&Zn?) 6-7

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Last-Dialed Number Inquiry (DL?) 6-8 Stored Command String Query (&ZC?) 6-8 Help Screens 6-8

Stop/Restart Display 6-8 Cancel Display 6-8

Basic Command Set ($) 6-8 Extended Command Set (&$) 6-9 Dialing (D$) 6-10 S-Register Functions (S$) 6-10 Percent Commands (%$) 6-11

PART II. REFERENCE

Appendix ALink Negotiation (Handshaking)

and Error Control

V.34 Handshaking A-1 V.Fast Class (V.FC) Handshaking A-2 U.S. Robotics V.32 terbo to U.S. Robotics V.32 terbo A-2 Other V. Protocol Operations A-3

Dual Standard Handshaking A-4

Error Control and Throughput A-4

V.42 Handshaking A-5 MNP Handshaking A-5 Data Compression A-5 Flow Control A-6 Throughput Guidelines A-7

Typical Throughput A-8

Appendix BSummaries and Tables

The RS-232 Interface B-2 Front Panel Indicators B-5 DIP Switch Summary B-7 Default Settings B-9

Factory Templates

&F1 Hardware Flow Control (Default) B-10 &F2 Software Flow Control B-11 &F3 HST Cellular B-12 &F0 No Flow Control B-13

NVRAM Options B-14 S-Register Summary B-15 ASCII Chart B-28

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Appendix CAlphabetical Command Summary

Command Set Usage C-1 Basic Command Set C-2 Ampersand (&) Command Set C-9 Percent (%) Command Sets C-18

Appendix DDial Security/Remote Access

Dial Security D-1 Remote Access D-10

Appendix ETroubleshooting Appendix FSynchronous and Leased Line Operations

Synchronous F-1

V.25 bis F-4 Online synchronous F-9

Dedicated Line and Leased Line Operations F-15

Appendix GAdditional Operations

Cellular Operations G-2 Voice/Data (External Modems Only) G-4 Hewlett Packard 3000 Installations G-8 MI/MIC Operations (External Modems Only) G-9

Appendix HModem Testing

Testing with &T H-1

Ending a Test&T0, S18 H-1 Analog Loopback&T1, &T8 H-2 &T2 H-4 Digital Loopback&T3 H-4 &T4, &T5 H-5 Remote Digital Loopback&T6, &T7 H-5

Testing with Register S16 H-8

Analog LoopbackS16=1D H-9 Dial TestS16=2 H-9 Test PatternS16=4 H-10 Remote Digital LoopbackS16=8 H-10

Appendix ISoftware Upgrades Appendix JGlossary Appendix KTechnical Specifications Index

viii Table of Contents

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.

COURIER HIGH SPEED MODEMS

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.

Warranty Information ix

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FCC REGISTRATION

FCC68: CJEUSA-73130-FA-E

RINGER EQUIVALENCE: 0.4B

FCC15:

CJE-0263 (External modem) CJE-158-243 (Internal modem) 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 radioelectriques 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

x Warranty Information

COURIER HIGH SPEED MODEMS

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

Regulatory Information xi

COURIER HIGH SPEED MODEMS

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.

xii Regulatory Information

CHAPTER 1. 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

COURIER HIGH SPEED MODEMS

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.

Features and Compatibility 1-1

COURIER HIGH SPEED 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—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.

1-2 Features and Compatibility

COURIER HIGH SPEED MODEMS

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.

Features and Compatibility 1-3

COURIER HIGH SPEED MODEMS

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.

1-4 Features and Compatibility

COURIER HIGH SPEED MODEMS

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

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.

Features and Compatibility 1-5

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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

1-6 Features and Compatibility

MNP Levels 2, 3 and 4 error control, level 5 data

ITU-T V.54 Analog, digital and remote digital loopback

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

TIA/EIA-592 Service Class 2.0 Asynchronous Facsimile

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

COURIER HIGH SPEED MODEMS

compression, 1200 bps and higher

testing

DCE Control Standard

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.

Features and Compatibility 1-7

COURIER HIGH SPEED MODEMS

CHAPTER 2. MODEM SET UP

HS AA CD OH RD SD TR MR RS CS SYN ARQ/

Figure 2.1—Courier V.34 Modem

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.

FAX

VOICE/DATA

V.34 Fax with

V.FC and V.32 bis

External Modem Set Up 2-1

COURIER HIGH SPEED MODEMS

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 inter- ference 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.

2-2 External Modem Set Up

• 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.

COURIER HIGH SPEED MODEMS

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.

External Modem Set Up 2-3

COURIER HIGH SPEED MODEMS

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.

4. Make sure that the modem’s power switch is OFF; press it towards the zero in the 0/1 icon on the bottom label.

5. 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.

6. 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).

7. 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.

1 2 3 4 5 6 7 8 9 10

OFF ON

Figure 2.2—DIP Switch Factory Settings

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.

2-4 External Modem Set Up

COURIER HIGH SPEED MODEMS

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.

8. 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.

To wall outlet

Figure 2.3—Cabled Courier Modem

POWER

ON/OFF PHONE JACKS SERIAL PORT INTERFACE

To wall jack

To phone

External Modem Set Up 2-5

To computer

COURIER HIGH SPEED MODEMS

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—it doesn't matter which at this time—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:

Go on to step 5.

2-6 External Modem Set Up

COURIER HIGH SPEED MODEMS

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>

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COURIER HIGH SPEED MODEMS

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>.

2-8 External Modem Set Up

CHAPTER 3. 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

COURIER HIGH SPEED MODEMS

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.

Review Chapter 4 so that you have a basic understanding of the modem's requirements and operation.

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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.

3-2 Internal Modem Set Up

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.

COURIER HIGH SPEED MODEMS

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.

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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 Serial Port

Port IRQ 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.

3-4 Internal Modem Set Up

Reset the Jumpers

Figure 3.1 shows an enlarged view of the modem's jumper switches. 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.

COURIER HIGH SPEED MODEMS

WARNING: Do not select an IRQ position until you've read the previous guidelines and reviewed your software documentation.

Figure 3.1Jumper Switch/Serial Port Settings

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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.

Figure 3.2Removing the Computer Cover

3-6 Internal Modem Set Up

COURIER HIGH SPEED MODEMS

3. Unscrew the solid bracket at the back of any available standard half-card slot.)

The bracket will pop out of the back, leaving an opening in DIP switches.

4. and a 2-inch groove. These grooves are lined on both sides with metal guides. Insert the modem board into the slot

modem board's edge connector firmly in the 3-inch groove.

Figure 3.3Inserting the Modem

Screw the vertical bracket at the back of the modem firmly to the computer's rear panel, as shown in Figure 3.3. This

and keeps the modem board firmly in place.

Internal Modem Set Up 3-

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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

3-8 Internal Modem Set Up

COURIER HIGH SPEED MODEMS

Review your communications software documentation for instructions.

AT <Enter>

If everything is correct, the modem responds as follows:

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.

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COURIER HIGH SPEED MODEMS

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>

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>.

3-10 Internal Modem Set Up

CHAPTER 4. 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:

COURIER HIGH SPEED MODEMS

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).

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COURIER HIGH SPEED MODEMS

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

4-2 Data Mode Operations

COURIER HIGH SPEED MODEMS

• 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>).

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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>

4-4 Data Mode Operations

COURIER HIGH SPEED MODEMS

" 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 switchhook (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.

Data Mode Operations 4-5

COURIER HIGH SPEED MODEMS

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 = 0−9.

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.

4-6 Data Mode Operations

Cancel Dialing

COURIER HIGH SPEED MODEMS

Store Phone Numbers

&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 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 = 0−9).

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.

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 twosecond pause, it redials.

Data Mode Operations 4-7

COURIER HIGH SPEED MODEMS

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>

4-8 Data Mode Operations

COURIER HIGH SPEED MODEMS

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=1−256.

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.

Hn On/off hook control.

H0 Hang up (go on hook). H1 Go off hook.

Hanging Up

Data Mode Operations 4-9

COURIER HIGH SPEED MODEMS

+++ 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.

4-10 Data Mode Operations

COURIER HIGH SPEED MODEMS

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−&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.

Data Mode Operations 4-11

COURIER HIGH SPEED MODEMS

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>

4-12 Data Mode Operations

COURIER HIGH SPEED MODEMS

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 1−7 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 1−7 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.

Data Mode Operations 4-13

COURIER HIGH SPEED MODEMS

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.

4-14 Data Mode Operations

COURIER HIGH SPEED MODEMS

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 • • • • • • • • 1/CONNECT • • • • • • • • 2/RING • • • • • • • • 3/NO CARRIER • • • • • • • • 4/ERROR • • • • • • • •

5/CONNECT 1200 • • • • • • • 6/NO DIAL TONE • • • • 7/BUSY • • • • • 8/NO ANSWER • • • • • 9/RESERVED

10/CONNECT 2400 • • • • • • • 11/RINGING • • • 12/VOICE • • 13/CONNECT 9600 • • • • • • • 18/CONNECT 4800 • • • • • • • 20/CONNECT 7200 • • • • • • • 21/CONNECT 12000 • • • • • • • 25/CONNECT 14400 • • • • • • • 47/CONNECT 16800 • • • • • • • 85/CONNECT 19200 • • • • • • • 91/CONNECT 21600 • • • • • • • 99/CONNECT 24000 • • • • • • • 103/CONNECT 26400 • • • • • • • 107/CONNECT 28800 • • • • • • •

Functions

Adaptive Dialing • • • • • • Wait for 2nd Dial Tone (W) • • • • • Wait for Answer (@) • • • • • Fast Dial • • • •

Table 4.1Result Code Options

NOTE: Additional messages indicate an error control

connection and the modulation for a call. See the next section, Additional Result Code Subsets.

Data Mode Operations 4-15

COURIER HIGH SPEED MODEMS

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 Dialing The modem attempts to use tone dialing and, if that

doesn't work, reverts to rotary dialing. Wait for Another The modem continues dialing as soon as it detects Dial Tone (W) another dial tone. See the dial options earlier in this

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.

Table 4.2Result Code Definitions

4-16 Data Mode Operations

COURIER HIGH SPEED MODEMS

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 57/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

Data Mode Operations 4-17

COURIER HIGH SPEED MODEMS

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 NONE) 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.

4-18 Data Mode Operations

COURIER HIGH SPEED MODEMS

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.

Data Mode Operations 4-19

COURIER HIGH SPEED MODEMS

&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.

4-20 Data Mode Operations

COURIER HIGH SPEED MODEMS

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).

Most communications programs support variable rates, but not all software supports fixed rates.

WARNING: To connect above 9600 bps, the serial port rate must be 19.2K, 38.4K, 57.6K, or 115.2K bps. If the local computer is limited to 9600 bps, V.32 terbo modems are limited to 9600 bps maximum, that is, V.32. Disable V.32 terbo modulation so that the modem does not switch its serial port rate up higher than 9600 bps. Do this by setting Register S34 to 3 (S34=3) and including that setting in the defaults you write to nonvolatile memory, as shown in Setting/Using Defaults earlier in this chapter.

&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.

Data Mode Operations 4-21

COURIER HIGH SPEED MODEMS

&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. This is the recommended setting, and is required for the Courier V.32 terbo to connect at 21.6K bps. Both modems must be U.S. Robotics modems with V.32 terbo to make a

21.6K bps connection.

&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.

4-22 Data Mode Operations

COURIER HIGH SPEED MODEMS

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)

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 poweron/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 poweron/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.

Data Mode Operations 4-23

COURIER HIGH SPEED MODEMS

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.

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.

4-24 Data Mode Operations

Flow Control

COURIER HIGH SPEED MODEMS

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.

Data Mode Operations 4-25

COURIER HIGH SPEED MODEMS

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.

4-26 Data Mode Operations

COURIER HIGH SPEED MODEMS

&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.

Data Mode Operations 4-27

COURIER HIGH SPEED MODEMS

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 Packard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 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 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.

4-28 Data Mode Operations

COURIER HIGH SPEED MODEMS

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 nontext (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.

Data Mode Operations 4-29

COURIER HIGH SPEED MODEMS

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.

4-30 Data Mode Operations

COURIER HIGH SPEED MODEMS

&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.

Data Mode Operations 4-31

COURIER HIGH SPEED MODEMS

&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.

4-32 Data Mode Operations

COURIER HIGH SPEED MODEMS

CHAPTER 5. FAX OPERATIONS AND CALL DETECTION

FAX OPERATIONS

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.

Fax Operations 5-1

COURIER HIGH SPEED MODEMS

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.

5-2 Fax Operations

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

COURIER HIGH SPEED MODEMS

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.

Fax Operations 5-3

COURIER HIGH SPEED MODEMS

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.

5-4 Fax Operations

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.

COURIER HIGH SPEED MODEMS

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

on the following page is an example.

Queries and Help Screens 6-1

COURIER HIGH SPEED MODEMS

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 #:

Figure 6.1Sample Result of ATI4 Command

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.

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 =

Figure 6.2Sample NVRAM Settings Screen

6-2 Queries and Help Screens

COURIER HIGH SPEED MODEMS

I6 During a connection, the modem monitors and stores infor-

mation 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.

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

Figure 6.3Sample Link Diagnostics Screen (ATI6)

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.

Queries and Help Screens 6-3

COURIER HIGH SPEED MODEMS

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, HST, 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.

6-4 Queries and Help Screens

COURIER HIGH SPEED MODEMS

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.

Queries and Help Screens 6-5

COURIER HIGH SPEED MODEMS

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 nonerror 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

6-6 Queries and Help Screens

COURIER HIGH SPEED MODEMS

I10 View Dial Security Account status. For security

administrators only, unless local security is disabled, S53=0 or S53.2=0.

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]

Figure 6.4Sample Dial Security Account Status Screen

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 SRegister, 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

Queries and Help Screens 6-7

COURIER HIGH SPEED MODEMS

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.

6-8 Queries and Help Screens

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 . .

Figure 6.5Sample Basic Commands HELP Screen

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.

COURIER HIGH SPEED MODEMS

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 . . .

Figure 6.6Sample Ampersand Commands HELP Screen

Queries and Help Screens 6-9

COURIER HIGH SPEED MODEMS

Dialing (D$)

At ATD$, the Courier displays this Dial command summary:

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

Figure 6.7Sample Dial Command HELP Screen

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.

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 . . .

Figure 6.8Sample S-Register HELP Screen

6-10 Queries and Help Screens

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.

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 . . .

COURIER HIGH SPEED MODEMS

Figure 6.9Sample Percent HELP Screen

Queries and Help Screens 6-11

COURIER HIGH SPEED MODEMS

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).

Link Negotiation and Error Control A-1

COURIER HIGH SPEED MODEMS

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.

A-2 Link Negotiation and Error Control

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.

COURIER HIGH SPEED MODEMS

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.

Link Negotiation and Error Control A-3

COURIER HIGH SPEED MODEMS

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

Overview

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.

A-4 Link Negotiation and Error Control

V.42 Handshaking

This international standard includes a two-stage handshaking process:

• A Detection phase that is based on an exchange of

• LAPM (Link Access Procedures for Modems) Negoti-

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.)

COURIER HIGH SPEED MODEMS

predefined characters.

ation. 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.

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.)

Link Negotiation and Error Control A-5

COURIER HIGH SPEED MODEMS

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.

A-6 Link Negotiation and Error Control

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.

COURIER HIGH SPEED MODEMS

• 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 turnaround delay. With earlier versions, however, throughput may be severely reduced due to short block lengths (possibly under 128 bytes) and acknowledgment turnaround time.

Link Negotiation and Error Control A-7

COURIER HIGH SPEED MODEMS

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.

A-8 Link Negotiation and Error Control

COURIER HIGH SPEED MODEMS

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

Link Negotiation and Error Control A-9

COURIER HIGH SPEED MODEMS

28.8K bps

File Type Typical throughput (cps)

Text file 6800 .ZIP files 3200 Database files 9600 Graphic files 5800

A-10 Link Negotiation and Error Control

CONTENTS

Default Settings S-Register Summary

COURIER HIGH SPEED MODEMS

APPENDIX B. SUMMARIES AND TABLES

The RS-232 Interface, with Pin Definitions Front Panel Indicators DIP Switch Summary

ASCII Chart

Summaries and Tables B-1

COURIER HIGH SPEED MODEMS

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 DB25P, DB-9P or, more typically, an 8-pin round plug connector. Check your computer documentation or with your computer dealer.

B-2 Summaries and Tables

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 ATcompatible 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.

DB-25 DB-9 Circuit Function Computer

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

COURIER HIGH SPEED MODEMS

Signal Flow

Modem

* Indicates Transmitter (TX) or Receiver (RX)

Table B.1RS-232 Interface Pin Definitions

Summaries and Tables B-3

COURIER HIGH SPEED MODEMS

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.

B-4 Summaries and Tables

COURIER HIGH SPEED MODEMS

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 setting) and

Ready the modem receives a DTR signal from the

computer or terminal. Also ON when the DTR override is on, DIP switch 1 ON.

Summaries and Tables B-5

COURIER HIGH SPEED MODEMS

Symbol Meaning Status

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 RTS

Send 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 Trans-

mit 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.

B-6 Summaries and Tables

USRobotics COURIER User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual