Usrobotics V 34 Users Manual FRONT

V.34 to the manual c7c4e21b-5d51-4e33-a32a-084b603c9f54

2015-02-03

: Usrobotics Usrobotics-V-34-Users-Manual-461193 usrobotics-v-34-users-manual-461193 usrobotics pdf

Open the PDF directly: View PDF .
Page Count: 245 [warning: Documents this large are best viewed by clicking the View PDF Link!]

COURIER

HIGH SPEED MODEM

Courier V.34 Dual Standard Fax

USER MANUAL

COURIER HIGH SPEED MODEMS

ii How to Use This Manual

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

COURIER HIGH SPEED MODEMS

How to Use This Manual iii

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 require-

ments and operation.

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 v

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

COURIER HIGH SPEED MODEMS

vi Table of Contents

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

COURIER HIGH SPEED MODEMS

Table of Contents vii

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

COURIER HIGH SPEED MODEMS

viii Table of Contents

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

COURIER HIGH SPEED MODEMS

Warranty Information ix

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 PUR-

CHASER. THIS WARRANTY IS IN LIEU OF ALL OTHER

WARRANTIES, EXPRESS OR IMPLIED, INCLUDING ANY

IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS

FOR A PARTICULAR USE OR PURPOSE, AND U.S.

ROBOTICS SHALL IN NO EVENT BE LIABLE TO

PURCHASER FOR INDIRECT OR CONSEQUENTIAL

DAMAGES OF ANY KIND OR CHARACTER.

Some states do not allow the exclusion or limitation of

incidental or consequential damages or allow limitations on

how long an implied warranty lasts, so the above limitations or

exclusion may not apply to you. This warranty gives you

specific legal rights. You may also have other rights which vary

from state to state.

Should you encounter problems in operating this device, follow

the instructions in Appendix E in Part II of this manual. The

appendix contains solutions to operating problems as well as

procedures to follow if there is an apparent modem

malfunction.

COURIER HIGH SPEED MODEMS

x Warranty Information

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 radio-

electriques depassant les limites applicables aux appareils

numeriques de la classe B prescrites dans le Reglement sur le

brouillage radioelectrique edicte par le ministere des

Communications du Canada.

CONNECTING TO THE TELEPHONE COMPANY

It is not necessary to notify the telephone company before

installing the modem. However, the telephone company may

request the telephone number(s) to which the Courier is

connected and the FCC information printed above.

If the modem is malfunctioning, it may affect the telephone

lines. In this case, disconnect the modem until the source of the

difficulty is traced. Do not use the modem on party or coin

telephone lines.

RADIO AND TELEVISION INTERFERENCE

This equipment generates and uses radio frequency energy,

and, if not installed and used properly in strict accordance with

the manufacturer's instructions, may cause interference to radio

and television reception. Courier high speed modems have

been tested and found to comply with the limits for a Class B

computing device in accordance with the specifications in Part

COURIER HIGH SPEED MODEMS

Regulatory Information xi

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

COURIER HIGH SPEED MODEMS

xii Regulatory Information

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.

COURIER HIGH SPEED MODEMS

Features and Compatibility 1-1

CHAPTER 1. FEATURES AND COMPATIBILITY

INTRODUCTION

Congratulations! The Courier modem you've purchased repre-

sents powerful, advanced electronic design that offers excep-

tional reliability, compatibility and flexibility at all standard

rates up to 28,800 or 28.8K bits per second (bps). The

transmission rate between the computer and modem,

depending on your equipment and software support, can be as

high as 115.2K bps.

Features

The following features and capabilities assure you of superior

reliability and performance.

Connections up to 28.8K bps

With the V.34 standard and the V.Fast Class modulation

scheme, two modems can connect at rates up to 28.8K bps,

twice as fast as the rates of standard ITU-T (formerly CCITT)

V.32 bis modems, which are limited to calls of 14.4K bps or less.

Software Upgrades

Courier high speed modems are now software upgradable,

allowing you quick, easy access to the latest advances in data

communication technology. See Appendix I.

Quick Connect

In V.32 terbo mode, Courier high speed modems can handshake

and start transmitting much faster than typical training times

that range between 9 and 18 seconds for other modems.

COURIER HIGH SPEED MODEMS

1-2 Features and Compatibility

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.

COURIER HIGH SPEED MODEMS

Features and Compatibility 1-3

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.

COURIER HIGH SPEED MODEMS

1-4 Features and Compatibility

Programmable Nonvolatile Memory

You can tailor your own default settings and store them in non-

volatile 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 con-

taining 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 speci-

fied 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.

COURIER HIGH SPEED MODEMS

Features and Compatibility 1-5

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 espe-

cially 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 alpha-

betic acronym instead of a numeric number. See Chapter 4.

COURIER HIGH SPEED MODEMS

1-6 Features and Compatibility

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

COURIER HIGH SPEED MODEMS

Features and Compatibility 1-7

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

compression, 1200 bps and higher

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

testing

Fax Standards

The Courier modem provides Group III-compatibility when

combined with Class 1 or Class 2.0 fax software. In addition,

the modem adheres to the following standards.

TIA/EIA-578 Service Class 1 Asynchronous Facsimile

DCE Control Standard

TIA/EIA-592 Service Class 2.0 Asynchronous Facsimile

DCE Control Standard

ITU-T V.17 14.4K/12K bps

ITU-T V.29 9600/7200 bps

ITU-T V.27 ter 4800/2400 bps

ITU-T V.21 300 bps

Other Compatibility Features

Other compatibility features include the following standards

and certification:

•Can be used with any computer or terminal that is com-

patible 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.

COURIER HIGH SPEED MODEMS

External Modem Set Up 2-1

CHAPTER 2. MODEM SET UP

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

FAX

VOICE/DATA V.34 Fax with

V.FC and V.32 bis

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.

COURIER HIGH SPEED MODEMS

2-2 External Modem Set Up

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 com-

puter 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.

COURIER HIGH SPEED MODEMS

External Modem Set Up 2-3

•If your machine has other than a 25- or 9-pin port, check

your computer documentation or consult your dealer to

find out what type of RS-232 connector is required.

WARNING: If you're planning to use the high speed

computer-to-modem rates of 115.K, 57.6K or 38.4K bps, follow

the instructions concerning the RS-232 cable in Appendix B.

The guidelines there will help you to avoid signal degradation

at very high speeds.

Communications Software. . .

. . .if the modem is attached to a computer instead of a terminal.

The software uses the modem's AT command set to control

many communications functions, including configuring the

modem, dialing, and answering calls, and also enables the

transfer of files and other operations.

Some users prefer their communications software to take

control of the modem, and are more comfortable with a

program that makes the modem almost transparent. Others

prefer a program that allows them to use the modem's AT

command set sometimes, and their software at other times,

depending on the task at hand.

Review Chapter 4 so that you have a basic understanding of the

modem's requirements and operation.

Telephone Adapter. . .

. . .if you have an older telephone installation that does not

have the appropriate modular wall jack and plug.

Adapters and RJ11C connectors are available from your

telephone company or computer dealer.

YOU SHOULD. . .

Refer to Appendix F. . .

. . .if your phone line is user-installed or if it is leased from the

telephone company.

COURIER HIGH SPEED MODEMS

2-4 External Modem Set Up

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 conven-

tional 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.

OFF

1 2 3 4 5 6 7 8 9 10

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.

COURIER HIGH SPEED MODEMS

External Modem Set Up 2-5

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.

POWER

ON/OFF PHONE JACKS SERIAL PORT INTERFACE

To wall outlet

To wall jack

To phone

To computer

Figure 2.3—Cabled Courier Modem

COURIER HIGH SPEED MODEMS

2-6 External Modem Set Up

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.

COURIER HIGH SPEED MODEMS

External Modem Set Up 2-7

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>

COURIER HIGH SPEED MODEMS

2-8 External Modem Set Up

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>.

COURIER HIGH SPEED MODEMS

Internal Modem Set Up 3-1

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

The Courier modem has minimal operational requirements. Be

sure to read the information in the front of this manual about

radio and television interference and connecting to the phone

company. In addition, you should be aware of the following

requirements.

Communications Software. . .

. . .if the modem is attached to a computer instead of a terminal.

The software uses the modem's AT command set to control

many communications functions, including configuring the

modem, dialing, and answering calls, and also enables the

transfer of files and other operations.

Some users prefer their communications software to take

control of the modem, and are more comfortable with a

program that makes the modem almost transparent. Others

prefer a program that allows them to use the modem's AT

command set sometimes, and their software at other times,

depending on the task at hand.

Review Chapter 4 so that you have a basic understanding of the

modem's requirements and operation.

COURIER HIGH SPEED MODEMS

3-2 Internal Modem Set Up

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 recog-

nizes up to four COM ports, although more can be pro-

grammed. 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.

COURIER HIGH SPEED MODEMS

Internal Modem Set Up 3-3

If you're only using COM1 for a device, you can skip this sec-

tion 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 configura-

tion, as described below. Remember which serial port you

assign to the modem, because you must specify it to your

communications software later. The table in the next section

includes hexadecimal addresses, required by some software.

COM1: You may use this port if the computer does not have an

installed serial connector at COM1. (This situation is unlikely.)

You will have to modify some switches on the modem, so be

sure to read this entire section of the chapter. However, you

may prefer to leave the modem set to COM2 and proceed to

DIP Switches, just before the installation instructions.

COM2: If your computer is equipped with one serial connector

at COM1, and if you are not already using COM2 for another

device, use this port. (This is the most common configuration.)

Since the modem is already set to operate at COM2, skip the

rest of this section and proceed to DIP Switches, just before the

installation instructions.

COM3, COM4: If you have two serial devices that already use

COM1 and COM2, you can set the modem for either COM3 or

COM4. Review your communications software documentation

to be sure your program supports these additional serial ports.

(Most programs do.) If your software doesn't, you will have to

remove one of the other devices.

COURIER HIGH SPEED MODEMS

3-4 Internal Modem Set Up

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 prob-

ably 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 Depart-

ment 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.

COURIER HIGH SPEED MODEMS

Internal Modem Set Up 3-5

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.

WARNING: Do not select an IRQ position until you've read

the previous guidelines and reviewed your software docu-

mentation.

Figure 3.1Jumper Switch/Serial Port Settings

COURIER HIGH SPEED MODEMS

3-6 Internal Modem Set Up

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 man-

ual, if necessary, to see which rear panel screws to remove

before sliding the cover off.

NOTE: Our illustration shows expansion slots lined up ver-

tically on the floor of the computer. Some computers are

configured so that the expansion slots are stacked horizon-

tally, one on top of another. The following instructions

apply for both configurations.

Figure 3.2Removing the Computer Cover

COURIER HIGH SPEED MODEMS

Internal Modem Set Up 3-

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.

COURIER HIGH SPEED MODEMS

3-8 Internal Modem Set Up

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 tele-

phone 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 con-

nector from your phone company or computer dealer.

8. If you wish, plug your phone's cord into the second jack on

the modem, labeled PHONE. This enables you to use your

phone for conventional voice calls, and also allows you to

switch between voice and data transmission in the same

call. See Voice/Data Communications in Appendix G for more

information.

TESTING THE INSTALLATION

Use the following procedures to verify that your modem is

working properly.

1. Turn on your computer. Then turn the Courier's power

switch ON. The following front panel indicators, or LEDs,

will light up on the modem.

CD Carrier Detect, if you have set DIP switch 6 ON,

enabling the CD override

TR Data Terminal Ready, if you have set DIP switch 1

ON, enabling the DTR override

MR Modem Ready/Power ON

CS Clear to Send

2. If you're using a personal computer, load your software to

start the program. Set your terminal or software to 19.2K

bps or 9600 bps. In addition, set a word length of either 7

bits plus 1 parity bit, or 8 bits with no parity—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).

COURIER HIGH SPEED MODEMS

Internal Modem Set Up 3-9

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.

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.

COURIER HIGH SPEED MODEMS

3-10 Internal Modem Set Up

c. Make sure your software has put the computer in

Terminal mode, so that you can send the modem

commands. Then review Step 4, on the previous page.

d. Be sure that DIP switches 1 and 6 are set ON or OFF

according to your terminal or software requirements.

The table in Appendix B explains each function, and

you may also need to review your terminal or

communications software documentation.

e. If you set DIP switch 8 OFF, for Dumb mode, reset the

modem to Smart mode: set DIP switch 8 to ON.

f. The modem is shipped with DIP switch 3 ON, enabling

the result codes. If DIP switch 3 is OFF, set it to the ON

position. Then initiate the new switch setting with the

following reset command:

ATZ <Enter>

5. As a final check, make sure the modem gets a dial tone.

Type the following Dial command:

ATD <Enter>

On receipt of the command, the modem goes off hook and

waits for a dial tone. The OH indicator lights up, and you'll

hear the dial tone from the modem's speaker. To cancel the

operation, press any key.

Troubleshooting

If you don't hear the dial tone, first increase the volume by

using the L command. If that doesn't work, check to see

that the phone cable from the wall jack is connected to the

correct jack on the modem. If necessary, reconnect the

phone cable correctly. Then try the Dial command again,

ATD <Enter>.

COURIER HIGH SPEED MODEMS

Data Mode Operations 4-1

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:

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 stan-

dard 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).

COURIER HIGH SPEED MODEMS

4-2 Data Mode Operations

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

COURIER HIGH SPEED MODEMS

Data Mode Operations 4-3

•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>).

COURIER HIGH SPEED MODEMS

4-4 Data Mode Operations

DIALING/ANSWERING

Dialing

DnDial 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

DDial the number that follows and enter Originate mode.

Optional parameters:

P Pulse dial. Default.

TTone 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>

COURIER HIGH SPEED MODEMS

Data Mode Operations 4-5

" Dial the letters that follow (in an alphabetical phone

number). NOTE: If you are including another command

after the dial string, use closing quotation marks before

the additional command.

!Transfer a call (flash the switch-hook). This command

applies to modems in installations where other modems

share the phone line. The modem flashes the switch-

hook (goes off hook 0.5 seconds, on hook for 0.5 seconds

and off hook again) to dial the specified extension.

WThis 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.

COURIER HIGH SPEED MODEMS

4-6 Data Mode Operations

RReverse 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.

DSnDial the number stored in nonvolatile random access memory at

position n, where n = 0−9.

Cancel Dialing

To cancel Dial-command execution, press any key. If you

inadvertently hit a key on the keyboard while the modem is

dialing, the call is canceled. If this occurs, type the A/

command explained under Automated Redialing below.

When the modem receives a command, it stores the instruction

in its command buffer until it receives the next AT command.

Note that if you've sent the modem an additional command

since the Dial command, A/ re-executes that command instead

of redialing.

COURIER HIGH SPEED MODEMS

Data Mode Operations 4-7

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 two-

second pause, it redials.

COURIER HIGH SPEED MODEMS

4-8 Data Mode Operations

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

AForce 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>

COURIER HIGH SPEED MODEMS

Data Mode Operations 4-9

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 con-

ventional calls, disable Auto Answer when you are not

expecting incoming data calls. Otherwise, your modem

may answer the phone before you do, greeting a voice caller

with a high-pitched answer tone.

Hanging Up

HnOn/off hook control.

H0 Hang up (go on hook).

H1 Go off hook.

COURIER HIGH SPEED MODEMS

4-10 Data Mode Operations

+++ 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 dura-

tion 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.

COURIER HIGH SPEED MODEMS

Data Mode Operations 4-11

Returning Online

OnIf 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.

&FnThe 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.

COURIER HIGH SPEED MODEMS

4-12 Data Mode Operations

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>

COURIER HIGH SPEED MODEMS

Data Mode Operations 4-13

Resetting the Modem

ZSoftware 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

EnCommand 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.

FnOnline 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.

COURIER HIGH SPEED MODEMS

4-14 Data Mode Operations

In some microcomputer documentation, the term duplex is

applied to local online echoing, although the term is not techni-

cally 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.

MnSpeaker (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 non-

volatile random access memory.

Q0 Result codes displayed.

Q1 Result codes suppressed (quiet).

Q2 Result codes suppressed in Answer mode.

VnReturn 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.

COURIER HIGH SPEED MODEMS

Data Mode Operations 4-15

XnResult 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.

COURIER HIGH SPEED MODEMS

4-16 Data Mode Operations

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

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

COURIER HIGH SPEED MODEMS

Data Mode Operations 4-17

Additional Result Code Subsets

NOTE: ARQ (Automatic Repeat Request) is used in this

manual to denote calls under error control.

&AnEnable/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

COURIER HIGH SPEED MODEMS

4-18 Data Mode Operations

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 syn-

chronous 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.

COURIER HIGH SPEED MODEMS

Data Mode Operations 4-19

Modulation

BnHandshake 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

&MnEnable 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.

COURIER HIGH SPEED MODEMS

4-20 Data Mode Operations

&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.

&KnEnable/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 dif-

ferent kinds of files.

COURIER HIGH SPEED MODEMS

Data Mode Operations 4-21

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.

&BnSerial 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.

COURIER HIGH SPEED MODEMS

4-22 Data Mode Operations

&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.

&NnConnection 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.

COURIER HIGH SPEED MODEMS

Data Mode Operations 4-23

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

&CnCarrier Detect operations. At power-on and reset, the modem

operates according to the setting of DIP switch 6. This

command is not stored in nonvolatile memory as a power-

on/reset default.

&C0 CD override, CD always ON.

&C1 Normal CD operations. The Courier sends a CD signal

when it connects with another modem and drops the CD

when it disconnects.

&DnData Terminal Ready (DTR) operations. At power-on and reset,

the modem operates according to the setting of DIP switch 1.

This command is not stored in nonvolatile memory as a power-

on/reset default.

&D0 DTR override. The modem operates as though the DTR

is always ON.

&D1 Advance usage: If issued before connecting with another

modem, the modem can enter online command mode

during a call by toggling DTR. (Most communications

software packages have a method for toggling DTR.)

&D1 functions similarly to the escape code (+++), except

that this setting is independent of DIP switch 9.

If DIP Switch 1 is ON (DTR override) when you issue the

&D1 command, the DTR override is automatically turned

off. However, if you change the setting of DIP switch 1

after issuing &D1, the DIP switch setting takes

precedence.

COURIER HIGH SPEED MODEMS

4-24 Data Mode Operations

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.

&SnThe 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

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.

COURIER HIGH SPEED MODEMS

Data Mode Operations 4-25

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.

COURIER HIGH SPEED MODEMS

4-26 Data Mode Operations

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

&HnThis 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.

COURIER HIGH SPEED MODEMS

Data Mode Operations 4-27

&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), con-

trol 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.

COURIER HIGH SPEED MODEMS

4-28 Data Mode Operations

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 com-

mands, 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.

COURIER HIGH SPEED MODEMS

Data Mode Operations 4-29

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 com-

mands, the Courier either resumes or stops transmitting

data over the link and drops the characters from the data

stream.

If both modems are set to &I5, operators at each end can

signal the remote modem to stop sending, thereby

controlling the data flow on the phone link and

preventing their own modem's buffer from overflowing.

At the computer or terminal/modem interfaces, the

modems independently control the flow of data through

their Transmit Data (&H) settings.

Guidelines

Use of software flow control may prove satisfactory if you're

only transferring text files. However, if you're transferring non-

text (binary) files, or using an Xmodem-type protocol, disable

flow control entirely (&R1, &I0). In addition, set the modem to

&B0 and &N0, so that the serial port and connection rates are

equal.

S-REGISTERS

The S-Registers are used to set various timing parameters,

redefine selected ASCII characters, and other configuration

options. A detailed summary of the S-register functions is in

Appendix B. A less detailed summary is in the Quick-Reference

card.

Sr=nSet S-Register value: r is any S-Register; n must be a decimal

number between 0 and 255.

Sr.b=nAlternative 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.

COURIER HIGH SPEED MODEMS

4-30 Data Mode Operations

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.

&GnThis 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.

COURIER HIGH SPEED MODEMS

Data Mode Operations 4-31

&PnThis 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 Common-

wealth countries.

&P0 Make/break ratio, U.S./Canada: 39%/61%. Default.

&P1 Make/break ratio, United Kingdom, some

Commonwealth countries: 33%/67%.

MISCELLANEOUS COMMANDS

CnTransmitter enabled/disabled.

C0 Transmitter disabled; receive-only condition.

C1 Transmitter enabled. Default.

KnModem 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.

&YnBreak 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.

COURIER HIGH SPEED MODEMS

4-32 Data Mode Operations

&ZC=sWrite 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 set-

ting 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.

COURIER HIGH SPEED MODEMS

Fax Operations 5-1

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.

COURIER HIGH SPEED MODEMS

5-2 Fax Operations

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.

COURIER HIGH SPEED MODEMS

Fax Operations 5-3

FCC Notice

FCC part 68, rules regarding fax operation, has been amended

as follows:

Telephone facsimile machines—identification of the sender

of the message: It shall be unlawful for any person within

the United States to use a computer or other electronic

device to send any message via a telephone facsimile

machine unless such a message clearly contains, in a margin

at the top or bottom of each transmitted page or on the first

page of the transmission, the date and time it is sent and an

identification of the business, other entity, or individual

sending the message and the telephone number of the

sending machine or of such business, other entity, or

individual. Telephone facsimile machines manufactured on

and after December 20, 1992 must clearly mark such

identifying information on each transmitted page.

NOTES TO PROGRAMMERS

Lists of supported Class 1 fax commands and optional Class 2.0

commands are in Appendix K.

If you want to know more about the supported Class 1 fax

commands, refer to the standard for the Service Class 1 fax

protocol.

ANSI/EIA/TIA-578-1990 (EIA-578)

Asynchronous Facsimile DCE Control Standard

November, 1990 Approved: October 22, 1990

For more information on Class 2.0, refer to the standard for the

Service Class 2.0 fax protocol.

ANSI/EIA/TIA-592-1993 (EIA-592)

Asynchronous Facsimile DCE Control Standard

May, 1993

You can obtain copies of these standards by contacting Global

Engineering Documents, at 1-800-854-7179.

COURIER HIGH SPEED MODEMS

5-4 Fax Operations

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

COURIER HIGH SPEED MODEMS

Queries and Help Screens 6-1

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 Depart-

ment, you may be asked for this product code.

I1 The modem performs a checksum of its read-only memory

(ROM) and returns the result to the screen. This function is

used only in factory testing. The modem should always

read the same number.

I2 The modem performs a test of its random access memory

(RAM) and returns either the OK (0) or ERROR (4) result

code, followed by OK when the test is completed. You may

want to use this command as a checkpoint if the modem

appears to be malfunctioning.

I3 The modem returns the duration of the last call if set to K0.

It displays the actual time if set to K1. See the description of

the Kn command in Chapter 4.

I4 The modem displays its current configuration. Figure 6.1

on the following page is an example.

COURIER HIGH SPEED MODEMS

6-2 Queries and Help Screens

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

COURIER HIGH SPEED MODEMS

Queries and Help Screens 6-3

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 0Chars Received 0

Chars lost 0

Octets sent 0Octets Received 0

Blocks sent 0Blocks Received 0

Blocks resent 0

Retrains Requested 0Retrains Granted 0

Line Reversals 0Blers 0

Link Timeouts 0 Link Naks 0

Data Compression NONE

Equalization Long

Fallback Disabled

Last Call 00:00:00

Disconnect Reason is Keypress Abort

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.

COURIER HIGH SPEED MODEMS

6-4 Queries and Help Screens

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.

COURIER HIGH SPEED MODEMS

Queries and Help Screens 6-5

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

hangs up at loop loss.

Loss of carrier: The modem detected loss of the remote

modem's carrier and waited the duration specified in

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.

COURIER HIGH SPEED MODEMS

6-6 Queries and Help Screens

Unable to Retrain: After several attempts, disturbances on

the phone line prevented the modems from retraining, and

they could no longer transmit or receive data.

XID Timeout: The modems failed to negotiate the V.42

Detection (XID Exchange) phase.

Dial Security Disconnect Reason: Possible reasons the

answering modem may have hung up during a Dial Security

session are as follows:

Security Abort: The modem hung up because it received an

invalid password three times.

Prompting Not Enabled: The modem hung up because the

originating modem did not send an autopass password, and

prompting wasn't enabled.

No Prompting in Sync: The originating modem did not send

an autopass password, and the answering modem cannot

prompt for a password in any synchronous mode.

Non-ARQ Mode: The modem hung up because the

originating modem was set for error control and the

answering modem was set for non-error control.

Mode Incompatible: The modem hung up because both

modems were not set to the same error control setting.

No Prompting in Non-ARQ: Prompting was enabled, but the

modem hung up because the originating modem was set for

error control, and the answering modem was set for non-

error control. The answering modem cannot prompt when it

is set for non-error control.

I7 The modem returns a product configuration. If you have a

problem and call U.S. Robotics' Technical Support staff, you

may be asked to read this screen.

I8 Not used

I9 Not used

COURIER HIGH SPEED MODEMS

Queries and Help Screens 6-7

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 S-

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

COURIER HIGH SPEED MODEMS

6-8 Queries and Help Screens

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.

COURIER HIGH SPEED MODEMS

Queries and Help Screens 6-9

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 TTone 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.

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

COURIER HIGH SPEED MODEMS

6-10 Queries and Help Screens

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

PPulse Dialing

RCall 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

COURIER HIGH SPEED MODEMS

Queries and Help Screens 6-11

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 . . .

Figure 6.9Sample Percent HELP Screen

COURIER HIGH SPEED MODEMS

Link Negotiation and Error Control A-1

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 opera-

tions 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).

COURIER HIGH SPEED MODEMS

A-2 Link Negotiation and Error Control

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.

COURIER HIGH SPEED MODEMS

Link Negotiation and Error Control A-3

OTHER V. PROTOCOL OPERATIONS

Earlier, lower-speed V. protocols do not employ line probing.

Instead they use predefined answer tones to specify, or identify,

speed capabilities. These protocols define the following

maximum speeds.

•V.32 terbo: 19.2K bps, with an additional Courier-to-

Courier speed of 21.6K bps.

•V.32 bis: 14.4K bps.

•V.32: 9600 bps.

ASL (used in V.32 terbo and V.32 bis modes) is a strategy that

allows the modems' receivers and transmitters to act

independently of each other. We have always featured a

fallback/fall forward feature with error-correcting modems that

allows them to slow down if there are problems with the phone

line, in order to avoid data errors, and then speed up again. But

the independence of the receiving and transmitting channels

means that one channel or the other may slow down and then

speed up, without affecting the data flow on the other. The

result is more efficient line operation.

WARNING: Answering V.32 terbo modems shift their serial

port rate up to 38.4K (for 21.6K connections) if the calling V.32

terbo modem dials in at 21.6K. The answering V.32 terbo modem

then sends data to its computer at 38.4K bps. V.32 bis modems

shift their serial port rate to 19.2K bps in order to make 14.4K

bps connections. If your ocomputer or terminal does not

support these higher serial port rates, you need to disable V.32

terbo and/or V.32 bis. See Appendix B, Register S34.

NOTE: While many modems on the market now use the more

efficient speeds, there may be a problem in answering older,

"dumb" V.32 modems at 9600 bps. Register S28 is used to

modify the duration of the extra tones used in V.32 negotiations,

in the rare instance that this may be necessary. See S-Registers,

in Appendix B.

COURIER HIGH SPEED MODEMS

A-4 Link Negotiation and Error Control

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.

COURIER HIGH SPEED MODEMS

Link Negotiation and Error Control A-5

V.42 Handshaking

This international standard includes a two-stage handshaking

process:

•A Detection phase that is based on an exchange of

predefined characters.

•LAPM (Link Access Procedures for Modems) Negoti-

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.

MNP Handshaking

This protocol is supported by the ITU-T V.42 Recommendation.

It was originally developed by Microcom, Inc. and is now in the

public domain.

MNP is based on special protocol frames. If the remote modem

doesn't recognize an MNP Link Request, error control isn't

possible. (In HST asymmetrical mode, U.S. Robotics modems

use a proprietary scheme similar to MNP.)

Data Compression

If the modems successfully establish a V.42 connection, they

also negotiate for V.42 bis data compression. If they successfully

establish an MNP connection, they negotiate for MNP5 data

compression. The type of compression for a call, if any, is

reported in the ATI6 display, and in the CONNECT message if

the modem is set to &A3.

Modems using V.42 bis compression negotiate the following

options and report them in the ATI6 display.

•Dictionary size, that is, the amount of memory available

for compression table entries. (Entries are codes

devised for redundant data. The data is packed into

shorter data units, called code words, and unpacked by

the receiving modem.)

COURIER HIGH SPEED MODEMS

A-6 Link Negotiation and Error Control

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.

COURIER HIGH SPEED MODEMS

Link Negotiation and Error Control A-7

Throughput Guidelines

The following guidelines should help to make the most of the

modem's advanced performance features. In many instances,

experimentation and experience will indicate what works best

for your applications.

1. Optimal throughput is attained under the following

conditions:

•The communications software allows fixing the serial

port rate higher than the connection rate, by setting the

software to 115.2K, 57.6K, or 38.4K bps and setting the

modem to &B1.

If the software automatically switches serial port rates

to follow the connection rate, the modem's serial port

rate must be also set to follow the connection rate for

each call, &B0, and throughput will be limited.

Installations with specialized software may want to

enable a fixed serial port rate for ARQ calls and a

variable serial port rate for non-ARQ calls. See the &B2

command in Chapter 4.

•The call is under data compression.

•The data is comprised of text files rather than binary

files such as .EXE or .COM files. See the table at the end

of this appendix.

2. MNP5 compression is disabled for files that are already

compressed, and 8-bit binary files that appear to the modem

to be already compressed. MNP5 is disabled by setting the

modem to &K3.

3. The file transfer is not slowed down by a file-transfer

protocol. Many non-text files require a file transfer

protocol, but the results vary. For example, certain public

domain file transfer protocols have the following effects:

Kermit Newer versions support packets up to 9K and

a sliding window design to eliminate turn-

around delay. With earlier versions, however,

throughput may be severely reduced due to

short block lengths (possibly under 128 bytes)

and acknowledgment turnaround time.

COURIER HIGH SPEED MODEMS

A-8 Link Negotiation and Error Control

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.

COURIER HIGH SPEED MODEMS

Link Negotiation and Error Control A-9

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

COURIER HIGH SPEED MODEMS

A-10 Link Negotiation and Error Control

28.8K bps

File Type Typical throughput (cps)

Text file 6800

.ZIP files 3200

Database files 9600

Graphic files 5800

COURIER HIGH SPEED MODEMS

Summaries and Tables B-1

APPENDIX B. SUMMARIES AND TABLES

CONTENTS

The RS-232 Interface, with Pin Definitions

Front Panel Indicators

DIP Switch Summary

Default Settings

S-Register Summary

ASCII Chart

COURIER HIGH SPEED MODEMS

B-2 Summaries and Tables

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 accom-

modates 25 or 9 pins. For example, the port on the IBM PC,

PC/XT and most compatibles requires a DB-25S (socket) con-

nector, while the port on the IBM PC/AT and some compatibles

requires a DB-9S connector. Apple computers require a DB-

25P, DB-9P or, more typically, an 8-pin round plug connector.

Check your computer documentation or with your computer

dealer.

COURIER HIGH SPEED MODEMS

Summaries and Tables B-3

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 assign-

ments in the following table. DB-9 connectors for AT-

compatible computers should be wired at the computer end of

the cable as shown in the DB-9 column. If you're using an

Apple computer, we strongly recommend that you purchase a

Hardware Handshaking cable to get the highest possible reliability

performance.

Signal Flow

DB-25 DB-9 Circuit Function Computer

Modem

1 _ AA Chassis Ground both directions

2 3 BA Transmitted Data to modem

3 2 BB Received Data to computer

4 7 CA Request to Send to modem

5 8 CB Clear to Send to computer

6 6 CC Data Set Ready to computer

7 5 AB Signal Ground both directions

8 1 CF Carrier Detect to computer

12 _ SCF Speed Indicate to computer

15 _ DB Synchronous TX* Timing to computer

17 _ DD Synchronous RX* Timing to computer

20 4 CD Data Terminal Ready to modem

22 9 CE Ring Indicate to computer

24 _ DA Synchronous TX* Timing to modem

* Indicates Transmitter (TX) or Receiver (RX)

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

COURIER HIGH SPEED MODEMS

B-4 Summaries and Tables

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.

COURIER HIGH SPEED MODEMS

Summaries and Tables B-5

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 trans-

mits 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.

COURIER HIGH SPEED MODEMS

B-6 Summaries and Tables

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.

COURIER HIGH SPEED MODEMS

Summaries and Tables B-7

DIP SWITCH SUMMARY

PURPOSE

The DIP switches, located at the rear of the modem, are for

adapting the modem to your equipment and personal require-

ments. If necessary, review your software documentation.

Some users are able to move a single switch with a finger tip. If

this doesn't work for you, use a toothpick or other small

instrument. Do not use a lead pencil.

OPERATIONS

The DIP switch settings are power-on defaults, read by the

Courier when it is turned on. If changed when the modem is

on, switches 1-7, and 9 require the ATZ (software reset)

command to initiate the new settings. If you've set switch 8

OFF to disable command recognition, and want to return the

modem to Smart mode so that it responds to commands, just

reset switch 8 to ON.

When you issue the ATZ command, the modem reads its DIP

switch settings and resets either to its defaults (DIP switch 10

OFF) or factory settings (DIP switch 10 ON).

Factory

Switch Setting Function

1OFF Data Terminal Ready Operations

OFF Normal DTR operations: computer must

provide DTR signal for modem to accept

commands; dropping DTR terminates a

call

ON DTR always ON (Override)

2OFF Verbal/Numeric Result Codes

OFF Verbal (word) results

ON Numeric results

COURIER HIGH SPEED MODEMS

B-8 Summaries and Tables

Factory

Switch Setting Function

3ON Result Code Display

OFF Results suppressed

ON Results enabled

4OFF Command Mode Local Echo

OFF Keyboard commands displayed

ON Echo suppressed

5ON Auto Answer

OFF Modem answers on first ring

ON Auto answer disabled

6OFF Carrier Detect Operations

OFF Courier sends CD signal when it connects

with another modem, drops CD on

disconnect

ON CD always ON (Override)

7OFF Auxiliary, DIP Switch 3 ON

OFF Result codes in Originate and Answer

mode

ON Result codes in Answer mode disabled

8ON AT Command Set Recognition

OFF Command recognition disabled (Dumb

mode)

ON Recognition enabled (Smart mode)

9OFF Escape Code (+++) Response

OFF Modem hangs up, returns to Command

mode, sends NO CARRIER result

ON Modem maintains connection, returns to

Command mode, sends OK result

10 OFF Power-on and ATZ Reset Software Defaults

OFF Load from nonvolatile memory (NVRAM)

ON Load factory settings from read only

memory (ROM)

COURIER HIGH SPEED MODEMS

Summaries and Tables B-9

DEFAULT SETTINGS

USER-PROGRAMMABLE DEFAULTS

You can create your own default configuration and store it in

nonvolatile random access memory (NVRAM) using the &W

command described in Chapter 4. As long as DIP switch 10 is

OFF when you power on the modem, your defaults are loaded

into the modem's random access memory (RAM). To view your

NVRAM settings at any time, use the ATI5 command.

Tables on the next several pages list the options you can store in

NVRAM, including S-Register settings. If DIP switch 10 is ON

at power-on, the factory template 0 settings are loaded instead.

The modem has four factory setting templates (&F0−F3). By

default, the first time the modem is turned on, the modem loads

the settings stored in NVRAM, which are the same as the

settings in factory template 1 (&F1).

The following command example substitutes several user-

defined defaults for factory settings. The modem also stores the

rate, word length and parity it detects from the AT command

prefix.

AT X1 &B0 &M5 &H0 M3 &W <Enter>

The modem is shipped with DIP switch 10 OFF, so when it is

powered on it loads the settings from NVRAM. Until these

settings are changed, they are the same as the settings

permanently stored in factory settings template 1 (&F1). You

can alter any of these settings, create your own power-on

defaults, and then save them with the &W command. See

Chapter 4.

COURIER HIGH SPEED MODEMS

B-10 Summaries and Tables

Table B.3&F1 Hardware Flow Control Default Template

NVRAM Options Setting Description

Handshake option B0 ITU-T answer sequence

Error control/sync &M4 Normal/error control

Data compression &K1 Enabled

Transmit data hardware &H1 Hardware flow control

Rec'd data hardware flow control &R2 Enabled

Rec'd data software flow control &I0 Disabled

Serial port rate select &B1 Serial port rate fixed higher than

connect rate

Link rate select &N0 Variable

Result code subset X7 Extended. Includes all codes

except VOICE

Protocol response codes &A3 Full protocol codes

Tone/Pulse dialing PPulse dial

Online local echo F1 Disabled

Speaker control M1 ON during dial through connect

Remote Digital Loopback (RDL) &T5 Deny RDL

Normal/Leased/Cellular line &L0 Normal phone line

Data Set Ready operations &S0 Override enabled

Break handling &Y1 Clear buffer, send immediately

Stored telephone number &Z0−9=0 Blank

Pulse dial make/break ratio &P0 U.S./Canada

Guard tone &G0 U.S./Canada

Word length* 8

Parity* 0None

DTE rate* (Kbps) 19.2 _

* Detected by the modem from the AT prefix of the &W command

that writes your defaults to NVRAM. Set your software to the desired

word length, parity, and serial port rate defaults before sending the

modem the AT . . . &W string.

COURIER HIGH SPEED MODEMS

Summaries and Tables B-11

The &F2 and &F3 factory setting templates are similar to the

&F1, with the exception of the commands which are highlighted

in bold in tables B.4 and B.5.

Table B.4&F2 Software Flow Control Template

NVRAM Options Setting Description

Handshake option B0 ITU-T answer sequence

Normal/error control/sync &M4 Normal/error control

Data compression &K1 Enabled

Transmit data flow control &H2 Software flow control

Rec'd data hardware flow control &R1 Disabled

Rec'd data software flow control &I2 Enabled

Serial port rate select &B1 Serial port rate fixed higher than

connect rate

Link rate select &N0 Variable

Result code subset X7 Extended. Includes all codes

except VOICE

Protocol response codes &A3 Full protocol codes

Tone/Pulse dialing PPulse dial

Online local echo F1 Disabled

Speaker control M1 ON during dial through connect

Remote Digital Loopback (RDL) &T5 Deny RDL

Normal/Leased/Cellular line &L0 Normal phone line

Data Set Ready operations &S0 Override enabled

Break handling &Y1 Clear buffer, send immediately

Stored telephone number &Z0−9=0 Blank

Pulse dial make/break ratio &P0 U.S./Canada

Guard tone &G0 U.S./Canada

Word length* 8

Parity* 0None

DTE rate* (Kbps) 19.2 _

* Detected by the modem from the AT prefix of the &W command

that writes your defaults to NVRAM. Set your software to the desired

word length, parity, and serial port rate defaults before sending the

modem the AT . . . &W string.

COURIER HIGH SPEED MODEMS

B-12 Summaries and Tables

Table B.5&F3 HST Cellular Template

NVRAM Options Setting Description

Handshake option B1 HST-mode/Bell answer tone

Normal/error control/sync &M4 Normal/error control

Data compression &K1 Enabled

Transmit data flow control &H1 Hardware flow control

Rec'd data hardware flow control &R2 Enabled

Rec'd data software flow control &I0 Disabled

Serial port rate select &B1 Serial port rate fixed higher than

connect rate

Link rate select &N0 Variable

Result code subset X7 Extended. Includes all codes

except VOICE.

Protocol response codes &A3 Full protocol codes

Tone/Pulse dialing PPulse dial

Online local echo F1 Disabled

Speaker control M1 ON during dial through connect

Remote Digital Loopback (RDL) &T5 Deny RDL

Normal/Leased/Cellular line &L2 HST Cellular

Carrier loss wait time S10=30 Waits 3 seconds before hanging up

Data Set Ready override &S0 Enabled

Break handling &Y1 Clear buffer, send immediately

Stored telephone number &Z0−9=0 Blank

Pulse dial make/break ratio &P0 U.S./Canada

Guard tone &G0 U.S./Canada

Word length* 8

Parity* 0None

DTE rate* (Kbps) 19.2 _

* Detected by the modem from the AT prefix of the &W command

that writes your defaults to NVRAM. Set your software to the desired

word length, parity, and serial port rate defaults before sending the

modem the AT . . . &W string.

COURIER HIGH SPEED MODEMS

Summaries and Tables B-13

If DIP switch 10 is ON when the modem is powered on, or you

load factory template 0 (&F0), the following settings take effect.

The differences between factory template 0 (&F0) and factory

template 1 (&F1) are noted in bold.

Table B.6&F0 No Flow Control Low PerformanceTemplate

NVRAM Options Setting Description

Handshake option B0 ITU-T answer sequence

Normal/error control/sync &M4 Normal/error control

Data compression &K1 Enabled

Transmit data flow control &H0 Disabled

Rec'd data hardware flow control &R1 Disabled

Rec'd data software flow control &I0 Disabled

Serial port rate select &B0 Detect from AT command:

variable rate

Link rate select &N0 Variable

Result code subset X1 Basic

Error-control response codes &A1 Enabled

Tone/Pulse dialing PPulse dial

Online local echo F1 Disabled

Speaker control M1 ON during dial through connect

Remote Digital Loopback (RDL) &T5 Deny RDL

Normal/Leased/Cellular line &L0 Normal phone line

Data Set Ready operations &S0 Override enabled

Break handling &Y1 Clear buffer, send immediately

Stored telephone number &Z0−9=0 Blank

Pulse dial make/break ratio &P0 U.S./Canada

Guard tone &G0 U.S./Canada

Word length* 7

Parity* 1Even

DTE rate* (bps) 9600 _

* Detected by the modem from the AT prefix of the &W command

that writes your defaults to NVRAM. Set your software to the desired

word length, parity, and serial port rate defaults before sending the

modem the AT . . . &W string.

COURIER HIGH SPEED MODEMS

B-14 Summaries and Tables

Table B.7NVRAM Options

Factory

NVRAM S-Register Options Setting

S0 Auto Answer 1

S2 Escape code character 43

S3 Carriage Return character 13

S4 Line Feed character 10

S5 Backspace character 8

S6 Dial wait-time, sec. 2

S7 Carrier wait-time, sec. 60

S8 Dial pause, sec. 2

S9 Carrier Detect time, 1/10th sec. 6

S10 Carrier loss wait-time, 1/10th sec. 7

S11 Tone duration, spacing, msec. 70

S12 Escape code guard time, 1/50th sec. 50

S13 Bit-mapped functions* 0

S15 Bit-mapped functions* 0

S19 Inactivity/hang up timer 0

S21 Break length, 1/100th msec. 10

S22 XON character 17

S23 XOFF character 19

S24 Pulsed DSR duration, 2/100th sec. 150

S26 RTS/CTS delay time, 1/100th sec. 1

S27 Bit-mapped functions* 0

S28 V.32 handshake time, 1/10th sec. 8

S29 V.21 handshake time, 1/10th sec. 20

S32 Voice/Data Switch Options 9

S33 Bit-mapped functions* 0

S34 Bit-mapped functions* 0

S38 Disconnect wait time, sec. 0

S41 Allowable remote login attempts 0

S42 Remote Access ASCII character 126

S43 Remote guard time, 1/50th sec. 200

S44 Re-establish leased-line connect, sec. 15

S51 Bit-mapped functions* 0

S53 Bit-mapped functions* 0

S54 Bit-mapped functions* 0

S55 Bit-mapped functions* 0

S56 Bit-mapped functions* 0

S57 Bit-mapped functions* 0

* Bit-mapped registers have up to eight functions. See

descriptions later in this appendix or a briefer summary in the

Quick Reference Card.

COURIER HIGH SPEED MODEMS

Summaries and Tables B-15

S-REGISTER SUMMARY

USAGE

The default values are those users typically require. Change the

settings of an S-Register with the ATSr=n command, where r is

the register and n is a decimal value from 0-255:

ATS13=8 <Enter>

The modem does not perform a value-range check. Some

values you select may not work with some equipment, and

you'll have to readjust the settings.

Some registers (S13, S14, S15, S16, S27, S34) are bit-mapped (bits

0-7). For example, turning on bit 0 of S13 causes the modem to

reset each time the computer or terminal drops its Data

Terminal Ready (DTR) signal. Turning on bit 3 of S13 causes

the modem, on receipt of DTR, to auto dial the number stored at

position 0 in NVRAM.

To turn on one or more bits in any bit-mapped register, use the

total of the values shown below. For example, S13=9 turns on

bits 0 (value of 1) and 3 (value of 8).

Alternatively, identify the bits to be turned on with the

following format: Sr.b=1, where r is the register and .b is the bit.

This format does not require knowledge of the bit's value.

S13.0=1 .3=1 is the equivalent of S13=9, above. To turn off a bit

function, set it to zero: S13.0=0.

To display the contents of a register, use ATSr? as in this

example:

ATS19? <Enter>

COURIER HIGH SPEED MODEMS

B-16 Summaries and Tables

S0 See DIP Sets the number of rings on which to

Switch 5 answer when in Auto Answer mode. S0=0

disables Auto Answer, the same as DIP

switch 5 ON (factory setting). S0=1

enables Auto Answer and the modem

answers on the first ring.

NOTE: If DIP switch 5 is OFF and S0=0,

Auto Answer remains disabled.

S1 0Counts and stores the number of rings

from an incoming call.

S2 43 Stores the ASCII decimal code for the

escape code character. Default character is

“+”. A value of 128-255 disables the

escape code.

S3 13 Stores the ASCII decimal code for the

Carriage Return character. Valid range is

0−127.

S4 10 Stores the ASCII decimal code for the Line

Feed character. Valid range is 0−127.

S5 8Stores the ASCII decimal code for the

Backspace character. A value of 128-255

disables the Backspace key's delete

function.

S6 2Sets the number of seconds the modem

waits before dialing. If set to X2, X4, X6,

or X7, the modem dials as soon as it

detects a dial tone (fast dials). If there is

no dial tone, the modem observes the

normal S6 timeout.

S7 60 Sets the number of seconds the modem

waits for a carrier. May be set for much

longer duration if, for example, the

modem is originating an international

connection.

COURIER HIGH SPEED MODEMS

Summaries and Tables B-17

S8 2Sets the duration, in seconds, for the pause

(,) option in the Dial command and the

pause between command re-executions (>

and A> commands).

S9 6Sets the required duration, in tenths of a

second, of the remote modem's carrier

signal before recognition by the Courier.

S10 7Sets the duration, in tenths of a second,

that the modem waits after loss of carrier

before hanging up. This guard time

allows the modem to distinguish between

a line hit, or other disturbance that

momentarily breaks the connection, from a

true disconnect (hanging up) by the

remote modem.

While we do not recommend connecting

the modem to a line with call waiting, if

you have call waiting you may wish to

adjust this setting upward to prevent the

modem from misinterpreting the signal for

a second call as a disconnect by the remote

modem. A better alternative is to contact

your phone company to find out how to

temporarily disable call waiting.

S11 70 Sets the duration and spacing, in

milliseconds, of dialed tones.

S12 50 Sets the duration, in fiftieths of a second,

of the guard time for the escape code

(+++) sequence.

COURIER HIGH SPEED MODEMS

B-18 Summaries and Tables

S13 0Bit-mapped register. Select the bit(s) you

want on and set S13 to the total of the

values in the Value column. For example,

ATS13=20 enables bit 2 (value = 4) and bit

4 (value = 16). Or use ATSr.b=0 (OFF) or 1

(ON). For example, ATS13.0=1 .3=1 turns

on bits 0 and 3. To turn a bit off, set that

bit to zero, as in ATS13.3=0.

Bit Value Result

0 1Reset when DTR drops

1 2Reverse normal Auto Answer

operation: on incoming RING,

enter Originate Mode and look

for Answer tone

2 4Disable 250 msec. pause before

result code display

3 8On DTR signal, Auto Dial the

number stored in NVRAM at

position 0

4 16 At power on/reset, Auto Dial

number stored in NVRAM at

position 0

5 32 Disable HST (used for testing

V.32 terbo in Dual Standard

modems)

6 64 Disable MNP Level 3 (used for

testing Level 2)

7 128 Custom applications

S14 0Bit-mapped register. Select the bit(s) you

want on and set S14 to the total of

the values in the Value column.

Bit Value Result

0 1 Disconnect on escape code

1–6 –Reserved

7 128 Disable retrains

COURIER HIGH SPEED MODEMS

Summaries and Tables B-19

S15 0Bit-mapped register. To set the register,

see the instructions for S13.

Bit Value Result

0 1Disable the modem's extra

high-frequency equalization if

it causes problems on shorter-

link callsHST-modems only

1 2Disable online fallback

2 4Disable 450 bps back channel

HST only

3 8Reset non-ARQ mode

Transmit buffer from 1.5K

bytes to 128*

4 16 Disable MNP Level 4; retrans-

mitting the larger Level 4 data

blocks may be a problem if you

expect a great number of

errors during a call

5 32 Set backspace key to delete

6 64 Some earlier 2400 bps MNP

modems, not made by U.S.

Robotics or Microcom, were

not fully compatible with the

MNP protocol. If you have

difficulty making a successful

2400 bps MNP connection with

a remote MNP modem, it may

be because of this incompati-

bility. Set S15 to 64 and try

again to make the connection.

7 128 Custom applications only

* The default 1.5K byte non-ARQ buffer allows data transfer

with X- and Ymodem-type file transfer protocols without using

flow control.

The 128-byte option allows remote users with slower modems

to stop data you're transmitting from scrolling off their screens.

When remote users send your computer an XOFF (<Ctrl-S>)

and you stop transmitting, the data in transit from your

modem's buffer doesn't exceed the size of their screen.

COURIER HIGH SPEED MODEMS

B-20 Summaries and Tables

S16 0Bit-mapped test register. To set the

information on testing, see Appendix H.

Bit Value Result

0 1Analog Loopback

1 2Dial test

2 4Test pattern

3 8Remote Digital Loopback

4 16 Reserved

5 32 Reserved

6 64 Reserved

S17 0Reserved.

S18 0Test timer for software-initiated loopback

testing (&Tn), disabled when S18 is set to

0. See Appendix H. Used to set the

duration of testing, in seconds, before the

modem automatically times out and

terminates the test.

S19 0Sets the duration, in minutes, for the

Inactivity Timer. The timer activates

when there is no data activity on the

phone line and at the timeout the modem

hangs up. S19=0 disables the timer.

S20 0Reserved.

S21 10 Sets, in 10-millisecond units, the length of

Breaks sent from the modem to the

computer or terminal. Applies to ARQ

mode only.

S22 17 Stores the ASCII decimal code for the

XON character.

S23 19 Stores the ASCII decimal code for the

XOFF character.

COURIER HIGH SPEED MODEMS

Summaries and Tables B-21

S24 150 Sets the duration, in 20-millisecond units,

between pulsed DSR signals when the

modem is set to &S2 or &S3. The default

is 3 seconds.

S25 5Sets DTR recognition time in 1/100th of a

second units.

S26 1Sets the duration, in 1/100th of a second

units, of the delay between RTS and the

modem's CTS response in synchronous

mode.

S27 0Bit-mapped register. To set the register,

see the instructions for S13.

Bit ValueResult

0 1 Enable ITU-T V.21 modulation

at 300 bps for overseas calls. In

V.21 mode, the modem an-

swers both Bell 103 and V.21

calls, but only originates V.21

calls.

1 2 Enable unencoded (non-trellis-

coded) modulation in V.32

mode; this option is part of the

ITU-T V.32 recommendation,

but is rarely used.

2 4 Disable V.32 modulation; used

for testing HST modulation in

Dual Standard modems.

3 8 Disable 2100 Hz answer tone to

allow two V.42 modems to

connect more quickly.

4 16 See next page.

5 32 See next page.

6 64 Reserved.

COURIER HIGH SPEED MODEMS

B-22 Summaries and Tables

7 128 Unusual software incompati-

bility. Some software may not

accept 7200, 12000, 14400,

16800, 19200 and 21600 bps

result codes. This setting

disables the codes and displays

the 9600 code instead. The

call's actual rate can be viewed

on the ATI6 screen.

Error control handshaking options: select the

total values of bits 4 and 5.

Bit 4 Bit 5 Result

0 0 Complete handshaking

sequence: V.42 Detection,

LAPM error control, MNP

16 0 Disable MNP

0 32 Disable V.42 Detection and

LAPM

16 32 Disable Detection phase, if you

know that the remote modem

does LAPM, but not the

Detection phase.

S28 8Sets the duration, in tenths of a second, of

the extra 3000/600 Hz answer tones sent

during V.32 handshaking. This gives V.32

modems additional time to connect in V.32

mode before timing out.

If there is difficulty answering older,

manually operated V.32 modems, for

example, modems that require a button to

be pushed in order to dial, try lengthening

the duration of the extra tones.

COURIER HIGH SPEED MODEMS

Summaries and Tables B-23

Setting S28 to zero eliminates the extra

tones, resulting in a faster connect time if,

for example, the modem is set to use V.21

modulation (300 bps) or V.23 modulation

(1200 bps).

S29 20 Sets the duration, in tenths of a second, of

the answer tones sent during V.21 hand-

shaking. Default = 20 (2 seconds). This

gives V.21 modems additional time to

connect in V.21 mode before timing out.

S30−S31 0Reserved.

S32 9Sets the function for the voice/data

switch. This is not a bit-mapped register.

Select the value for the desired function,

for example, ATS32=6.

ValueResult

0Disabled

1Voice/data, Originate mode.

See value 9.

2Voice/data, Answer mode

3Redial last number

4Dial number stored at

position 0

5Auto Answer on/off toggle

6Reset the modem

7Initiate Remote Digital

Loopback

8Busy out phone line toggle

9Default if a command string is

stored with the &ZC=string

command. When voice/data

switch is pushed and &ZC has

been enabled, modem executes

stored command string.

Otherwise acts like value 1,

Originate mode

NOTE: Only use the voice/data switch

when the modem is in Command mode .

COURIER HIGH SPEED MODEMS

B-24 Summaries and Tables

S33 0Setting this register to 1 (S33=1) enables a

reduced packet size.

S34 0Bit-mapped register. See instructions for

S13.

Bit Value Result

0 1 Disable V.32 bis. Used for

troubleshooting; U.S. Robotics'

Technical Support may require

that you disable V.32 bis for

testing purposes.

1 2 Disable the modem's

enhanced, proprietary V.32 bis

modulation. Used for

troubleshooting.

2 4 Disable the faster retrains that

occur during proprietary V.32

terbo modulation. Used for

troubleshooting.

3 8 Enable V.23. Required for

some British connections.

4 16 Change MR LED to DSR.

5 32 Enable MI/MIC; see Appendix

6 64 Disable the remote access busy

message.

7 128 Disable V.32 terbo.

S35−S37 0Reserved.

S38 0Sets the duration, in seconds, before a

forced hang-up and clearing of the

Transmit buffer, when DTR drops during

an ARQ call. This is provided to allow

time for a remote modem to acknowledge

receipt of all transmitted data. Default =

0: the modem immediately hangs up

when DTR drops. If the modem receives

the ATH command, it ignores S38 and

immediately hangs up.

COURIER HIGH SPEED MODEMS

Summaries and Tables B-25

S39−S40 0Reserved.

S41 0Sets the number of allowable remote

access login attempts, thus enabling or

disabling remote access. The default

setting of zero allows no remote login

attempts, thus disabling remote access. A

value of 1 or greater enables remote

access. If the number of unsuccessful

any further login attempts during the

remainder of that connection are refused.

S42 126 Stores the ASCII decimal code for the

remote access escape character. The

default character is a tilde (~).

S43 200 Sets the duration, in fiftieths of a second,

of the guard time for the remote access

(~~~~) sequence.

S44 15 Sets the duration, in seconds, of the delay

between when the modem senses loss of

carrier and when it attempts to re-

establish a leased-line connection.

S45−S50 0Reserved.

COURIER HIGH SPEED MODEMS

B-26 Summaries and Tables

S51 0Bit-mapped register. See instructions

for S13.

Bit Value Result

01Disable MNP/V.42 for

V.22 (1200 bps)

12Disable MNP/V.42 for

V.22 bis (2400 bps)

24Disable MNP/V.42 for

V.32/V.32 bis/V.32 terbo

(9600/14,400/19,200/

21,600 bps).

3−6 _ Reserved

7 128 Custom Applications.

Handset Exclusion Delay.

If the telephone and

modem share the same

line, and DTR is raised,

the modem takes control

of the phone line and

disconnects the voice call.

The modem stays on hook

for the duration specified

in S6 before it becomes a

data call.

Since there is no way to

detect if the telephone is in

use, the S6 delay occurs

even if the telephone is not

in use.

The phone is re-enabled

once the modem returns

on hook.

S52 Reserved.

COURIER HIGH SPEED MODEMS

Summaries and Tables B-27

S53 0Bit-mapped register. Select the Dial

Security features you want enabled by

setting S53 to the total of the values in the

Value column in the table below. For

example, S53=3, enables Dial Security with

prompting. S53=5 enables Dial Security,

and local-access password protection. Or

use ATSr.b=0 (OFF) or 1 (ON). For

example, ATS53.0=1 .2=1 turns on bits 0

and 2. To turn a bit off, set that bit to

zero, as in ATS53.2=0.

Bit Value Result

01Dial security enabled

12Prompting enabled

24Local-access password

protection enabled

NOTE: In addition, enabling local access

password protection disables the &Zn=s

command which stores up to ten phone

numbers because stored phone numbers

occupy the same space in NVRAM as the

dialback numbers for Dial Security

accounts.

S54 0Symbol rate bit-mapped register used

primarily by U.S.Robotics Technical

Support for debugging purposes.

Bit 6 (ATS54.6=1) disables Call Indicate

(CI).

Bit 7 (ATS54.7=1) disablesV.8.

COURIER HIGH SPEED MODEMS

B-28 Summaries and Tables

S55 0Trellis code bit-mapped register used

primarily by U.S.Robotics Technical

Support for debugging purposes.

S56 0Bit-mapped register primarily used

by U.S.Robotics Technical Support for

debugging purposes.

Bit 6 (ATS56.6=1) disables V.34

modulation.

Bit 7 (ATS56.7=1) disables V.FC

modulation.

S57 0Reserved for German operations.

COURIER HIGH SPEED MODEMS

Alphabetical Command Summary C-1

APPENDIX C. ALPHABETICAL COMMAND SUMMARY

Additional command summaries are in Chapter 4, on the

bottom panel of the modem, and in the Quick-Reference Card.

COMMAND SET USAGE

Follow these guidelines:

1. Your software must be loaded and if you are using a

computer, it must be in Terminal mode.

Some communications programs put the computer in

terminal mode automatically when they are loaded.

Others require you to display a communications

terminal screen, press a Function key, or perform some

other operation. Refer to your communications

software documentation for instructions.

In Terminal mode the computer acts as if it were a stan-

dard terminal such as a teletypewriter, rather than a

data processor. Keyboard entries go directly to the

modem, whether the entry is a modem command or

data to be transmitted over the phone lines. Received

data is output directly to the screen.

2. Type commands in either upper or lower case, not a

combination (AT or at—not At).

3. All commands except A/, A> and +++ are preceded by

the AT (attention) prefix and are executed with the

Enter/Carriage Return key (<Enter>).

4. Command length = 60 characters maximum. The

modem doesn't count the AT prefix, Carriage Return

character, or spaces. It counts (but doesn't act on)

punctuation such as hyphens and parentheses.

5. A missing numeric parameter is assumed to be zero, as

in the command to hang up: ATH <Enter> is the

equivalent of ATH0 <Enter>.

COURIER HIGH SPEED MODEMS

C-2 Alphabetical Command Summary

Example (spaces are not required, but are added here for

readability):

AT &K3 X2 DT 071 312 1234 <Enter>

AT Attention; a command follows.

&K3 Disable MNP5 data compression; use only

V.42 bis compression.

X2 Use the X2 result code subset.

DT Dial the following number using tone dialing.

<Enter> Execute the commands.

NOTE: The defaults listed are based on the modem's shipping

configuration: load from nonvolatile random access memory

(NVRAM), DIP switch 10 OFF, which is the same as the &F1

configuration template. For a complete listing of default

configuration templates, see Appendix B.

BASIC COMMAND SET

+++ Escape code operations. Once the modem is online to another

system, the only command it recognizes is an escape code of three

typed pluses, which forces the modem back to Command mode.

Do the following when issuing the command:

•Wait one second after sending the last item of data

•Type: +++

•Wait one second before typing any data

Do not type the AT prefix or a Carriage Return. The guard time

of one second before and after the code prevents the modem

from misinterpreting the occurrence of +++ in the transmitted

data stream.

If necessary, the character used in the escape code or the dura-

tion 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:

COURIER HIGH SPEED MODEMS

Alphabetical Command Summary C-3

DIP Switch 9 Response to +++

OFF Modem goes on hook (hangs up), sends NO

CARRIER result code (factory setting)

ON Modem maintains connection (Online-Command

mode), sends OK result code

The factory setting (OFF) forces an automatic disconnect when

you issue +++. An advantage of this is that you are not likely

to inadvertently run up an all-night phone bill.

Set DIP switch 9 ON if you want the modem to respond to +++

by entering Online-Command mode, enabling it to execute

commands and return online. (See the O command later in this

appendix.)

>If you know the modem you are calling is frequently busy,

include the Repeat command in the Dial string, as follows:

AT > DT 1234567 <Enter> or

AT DT 1234567 > <Enter>

The modem enters Repeat mode, dials the number, waits 60

seconds for a carrier (default), and hangs up. Then after a two-

second pause, it redials.

The cycle continues until the modems connect or the modem

reaches a maximum of 10 attempts.

AForce Answer mode when the modem hasn't received an

incoming call.

A/ Re-execute the last issued command. A/ doesn't take the AT

prefix or a Carriage Return, and can be used to redial.

A> This command combines the features of both the A/ and >

commands. The modem enters Repeat mode and redials the

Dial string in the command buffer. Like the A/ command, A>

does not take the AT prefix or a Carriage Return.

AT Attention command prefix. Use AT alone to test for the OK

result code. AT must prefix all commands except A/, A> and

+++.

Any Terminate the current dialing operation resulting from an

key issued Dial command; terminate Repeat mode (> or A>).

COURIER HIGH SPEED MODEMS

C-4 Alphabetical Command Summary

BnHandshake options for international calls above 1200 bps.

B0 ITU-T (formerly CCITT) answer sequence. Default. This

is required to answer all V.32-type calls as well as calls

from overseas.

B1 Bell answer tone. This setting selects HST modulation in

Dual Standard modems; but should only be used if the

modem is not required to answer V.32-type calls.

NOTE: This setting is required for HST cellular calls.

CnTransmitter enabled/disabled.

C0 Transmitter disabled; receive-only condition.

C1 Transmitter enabled (Default).

DnDial the specified phone number; also execute Dial options.

The maximum number of characters allowed is 36, including the

AT prefix, punctuation and spaces. The Carriage Return (Enter

key) isn't counted as a character.

NOTE: With the exception of the Dial options, the modem

ignores any commands issued after D in the same command

string.

DDial the number that follows and enter Originate mode.

Optional parameters:

P Pulse dial (Default).

TTone dial.

,(Comma) Pause for 2 seconds before continuing to dial.

;Return to Command mode after dialing.

" Dial the letters that follow (in an alphabetical phone

number).

!Transfer a call (flash the switch-hook). This command

applies to modems in installations where other modems

share the phone line. The modem flashes the switch-

hook (goes off hook 0.5 seconds, on hook for 0.5 seconds

and off hook again) to dial the specified extension.

WThis command is useful in situations where you must

wait for a second dial tone before continuing dialing.

COURIER HIGH SPEED MODEMS

Alphabetical Command Summary C-5

@Wait for an answer (with X3 or higher). The @ command

can be used in the Dial string to tell the modem to detect

at least one ring, wait for five seconds of silence at the

other end of the call, and then continue to execute the

Dial string.

/A slash (/) causes a pause of only 125 milliseconds.

RReverse frequencies. This command allows calls to an

originate-only modem. It reverses the modem's

originate/answer frequencies, forcing the Courier to dial

out at the answer frequency.

DL Dial the last-dialed number. The modem stores each Dial

command until it receives the next Dial command. Use DL

instead of A/, described on the next page, if you wish to send

the modem non-Dial commands before dialing again.

DSnDial the number stored in nonvolatile random access memory at

position n, where n = 0−9.

EnCommand mode local echo. Enables/disables the display of

your typed commands. If double characters appear on the

screen, both the modem's local echo and your software's local

echo are on.

The Courier is shipped with DIP switch 4 OFF, enabling local

echo. The En command controls the local echo for a current

session, independently of the switch setting.

E0 Command mode echo OFF. The modem does not

display keyboard commands.

E1 Command mode echo ON.

FnOnline local echo. This command causes the modem to display

a copy of the data it is transmitting to another system.

F0 Online echo ON. Sometimes called half duplex. As the

modem transmits data to a remote system, it also sends a

copy of the data to the screen.

F1 Online echo OFF. Sometimes called full duplex. Default.

HnOn/off hook control.

H0 Hang up (go on hook).

H1 Go off hook.

COURIER HIGH SPEED MODEMS

C-6 Alphabetical Command Summary

InInquiry

I0 Display product code

I1 Display results from ROM checksum

I2 Display results from RAM test

I3 Display the duration of the last call

I4 Display current modem settings

I5 Display NVRAM settings

I6 Display Dial diagnostics summary of the last call

I7 Display product configuration information

I8 Reserved

I9 Reserved

I10 Display dial security account status information

I11 Reserved

KnModem 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.

LnSpeaker volume control (internal modems only)

L0 Low

L1 Low

L2 Medium (default)

L3 High

NOTE: External modems will return an OK message to this

command, but the volume will not change. The volume button

must be used to alter volume.

COURIER HIGH SPEED MODEMS

Alphabetical Command Summary C-7

MnSpeaker (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.

OnIf DIP switch 9 is ON (on detection of the escape code the

modem maintains the connection), you can issue commands

and then toggle the modem back online with the On command.

There are two ways to return online.

ATO0 Return online (normal).

ATO1 Return online and retrain. Use to have the modem re-

synchronize if there were errors in a non-ARQ data

transfer.

Qn Enable/suppress the display of result codes. The Courier is

shipped with DIP switch 3 ON, to display result codes. Use the

Qn command to control the display for a current session,

independently of the switch setting.

Q0 Result codes displayed.

Q1 Result codes suppressed (quiet).

Q2 Result codes suppressed in Answer mode.

Sr=nSet S-Register value: r is any S-Register; n must be a decimal

number between 0 and 255.

Sr.b=nAlternative 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.

VnReturn result codes in words or numbers (Verbal/Numeric

mode).

V0 Numeric mode.

V1 Verbal mode.

COURIER HIGH SPEED MODEMS

C-8 Alphabetical Command Summary

XnResult code set options. Use the following table (Default = X7,

all codes except 12/VOICE). For result codes in synchronous

operations, see Appendix F.

Setting

Result Codes X0 X1 X2 X3 X4 X5 X6 X7

0/OK ••••••••

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 • • • •

ZSoftware 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.

COURIER HIGH SPEED MODEMS

Alphabetical Command Summary C-9

AMPERSAND (&) COMMAND SET

&AnEnable/disable additional result code subsets. See the Xn

command.

&A0 ARQ result codes are disabled.

&A1 ARQ result codes enabled.

&A2 Additional VFC, HST, or V32 modulation indicator.

&A3 Additional error control indicator (LAPM, HST, MNP,

SYNC, or NONE) and data compression type (V42BIS or

MNP5). Default.

&BnSerial port rate variable or fixed.

&B0 Variable rates.

&B1 Fixed rate. Default. The modem always communicates

with the computer at the rate at which you have set the

terminal or software, regardless of the connection rate.

This setting is not affected by the &N setting. However,

the serial port rate must be equal to or higher than the &Nn

rate.

&B2 Fixed for ARQ calls/Variable for non-ARQ calls. Answer

mode only. When the modem goes off hook and

connects in ARQ mode, it shifts its serial port rate up to a

user-specified rate, for example, 38.4K bps. If the

connection is not under error control, the modem

behaves as if it were set to &B0 and switches its serial

port rate to match the connection rate of each call.

&CnCarrier Detect operations. At power-on and reset, the modem

operates according to the setting of DIP switch 6. This

command is not stored in nonvolatile memory as a power-

on/reset default.

&C0 CD override, CD always ON.

&C1 Normal CD operations. The Courier sends a CD signal

when it connects with another modem and drops the CD

when it disconnects.

COURIER HIGH SPEED MODEMS

C-10 Alphabetical Command Summary

&DnData Terminal Ready (DTR) operations. At power-on and reset,

the modem operates according to the setting of DIP switch 1.

This command is not stored in nonvolatile memory as a power-

on/reset default.

&D0 DTR override. The modem operates as though the DTR

is always ON.

&D1 Advance usage: If issued before connecting with another

modem, the modem can enter online command mode

during a call by toggling DTR. &D1 functions similarly

to the escape code (+++), except that this setting is

independent of DIP switch 9.

If DIP switch 1 is ON (DTR override) when you issue the

&D1 command, the DTR override is automatically turned

off. However, if you change the setting of DIP switch 1

after issuing &D1, the DIP switch setting tales

precedence.

Return online with the On command, or hang up with the

Hn command.

&D2 Normal DTR operations. The terminal or computer must

send a DTR signal for the modem to accept commands.

Dropping DTR terminates a call.

&FnThe modem is shipped with four configurations (templates),

&F0−&F3, stored in permanent nonprogrammable memory

(ROM). Appendix B includes configuration listings for each

template. Any one of the templates may be loaded into current

memory (AT &Fn) or written to nonvolatile memory and reset

default (AT &Fn &W). Note, however, that &F0 is always

loaded into memory if DIP switch 10 is ON.

&F0 Load No Flow Control template settings

&F1 Load Hardware Flow Control template settings (Default)

&F2 Load Software Flow Control template settings

&F3 Load HST Cellular template settings

COURIER HIGH SPEED MODEMS

Alphabetical Command Summary C-11

&GnThis 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.

&HnTransmit data flow control is for data transmitted to the modem

by its attached computer or terminal. The modem monitors its

buffer as data comes from the computer or modem. If the

buffer approaches 90% capacity, the modem signals the

computer or terminal to stop transmitting. When the modem

has sent enough data over the link to half empty the buffer, it

signals the computer or terminal to resume transmitting.

&H0 Transmit Data flow control disabled.

&H1 Hardware flow control. Default. Requires that your

computer or terminal and software support Clear to Send

(CTS) at the RS-232 interface.

&H2 Software flow control. Requires that your software

support XON/XOFF signaling.

&H3 Use both hardware and software flow control. If you are

unsure about what your equipment supports, select this

option.

&InReceived data software flow control.

&I0 Disables XON/XOFF flow control of received data.

Default.

&I1 The Courier acts on your typed XON/XOFF commands,

Ctrl-S or Ctrl-Q, and passes them to the remote

computer.

COURIER HIGH SPEED MODEMS

C-12 Alphabetical Command Summary

&I2 The Courier acts on your XON/XOFF commands, but

removes them from the data stream instead of passing

them to the remote computer. This is the recommended

setting for ARQ mode.

&I3 Hewlett PackardHost mode. Applies only to modems

attached to an HP mainframe that uses the ENQ/ACK

protocol. Use in ARQ 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 have &I5 capability.

&KnEnable/disable data compression.

&K0 Data compression disabled.

&K1 Auto enable/disable. Default. The modem enables

compression if the serial port rate is fixed, &B1, and

disables compression if the serial port rate follows the

connection rate, &B0, because compression offers no

throughput advantage when the serial port and

connection rates are equal. Compression may even

degrade throughput.

&K2 Data compression enabled. Use this setting to keep the

modem from disabling compression.

&K3 Selective data compression. The modem negotiates only

for V.42 bis compression, and disables MNP Level 5

(MNP5) compression. Use this setting to transfer 8-bit

binary files, .ZIP files, and other files that are already

compressed.

&MnEnable 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.

COURIER HIGH SPEED MODEMS

Alphabetical Command Summary C-13

&M1 This setting is exclusive of the modems' error control and

is used only for online synchronous mode without V.25

bis. See Appendix F for more information.

&M2 Reserved.

&M3 Reserved.

&M4 Normal/ARQ mode. Default. If an ARQ connection isn't

made, the modem operates in Normal mode, as though it

were set to &M0.

&M5 The modem enters ARQ asynchronous mode. The

modem hangs up if an ARQ connection cannot be made.

&M6 The modem enters V.25 bis synchronous mode, using a

character-oriented link protocol similar to BISYNC. See

Appendix F for more information.

&M7 The modem enters V.25 bis synchronous mode, using the

HDLC link protocol.

&NnConnection 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.

COURIER HIGH SPEED MODEMS

C-14 Alphabetical Command Summary

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)

&PnThis 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 Common-

wealth countries.

&P0 Make/break ratio, U.S./Canada: 39%/61%. Default.

&P1 Make/break ratio, United Kingdom, some

Commonwealth countries: 33%/67%.

&RnReceived data hardware (RTS) flow control

&R0 Delay Clear to Send Response after Request to Send

signal (RTS/CTS delay).

&R1 The modem ignores RTS. This setting is required if your

computer or terminal or software does not support RTS.

&R2 Hardware flow control of received data enabled.

Default. The modem sends data to the computer or

terminal only on receipt of the RTS signal.

&SnThe modem sends the computer or terminal a Data Set Ready

(DSR) signal via the RS-232 interface. (Data Set is industry

jargon for modem.)

&S0 DSR is always ON (override). Default.

&S1 In Originate mode, the modem sends the DSR after it

dials, when it detects the remote modem's answer tone.

In Answer mode, the modem sends the DSR after it

sends an answer tone.

COURIER HIGH SPEED MODEMS

Alphabetical Command Summary C-15

&S2 This option is for specialized equipment such as

automatic callback units. On loss of carrier, the modem

sends a pulsed DSR signal with Clear to Send (CTS)

following Carrier Detect (CD).

&S3 This is the same as &S2, but without the CTS following

CD.

&S4 The modem sends the computer a DSR signal at the same

time as it sends the Carrier Detect (CD).

&TnModem testing

&T0 End test

&T1 Initiate Analog Loopback (AL) testing

&T2 Reserved

&T3 Initiate Local Digital Loopback (LDL) testing

&T4 Grant Remote Digital Loopback (RDL)

&T5 Deny RDL

&T6 Initiate RDL testing

&T7 Initiate RDL with self test and error detection

&T8 Initiate AL with self test and error detection

&W Write the desired template to NVRAM, using the &W

command.

&W0 Write to NVRAM template 0

&W1 Write to NVRAM template 1

&XnSynchronous transmit clock timing signals setting. Determines

whether the modem or DTE will generate the timing signals.

&X0 The Courier is the source of the Transmit clock timing

signals and sends them to your DTE over the RS-232

interface. The DTE rate will follow the connection rates.

Default.

COURIER HIGH SPEED MODEMS

C-16 Alphabetical Command Summary

&X1 The DTE is the source of the Transmit clock timing

signals and sends them to the Courier over the RS-232

interface. This setting is used typically in leased line

multiplexed operations. (Multiplexors divide the phone

channel so that the channel carries several calls at the

same time.)

The DTE ignores the Courier's clock timing signals and

negotiates the DTE and connection rates.

&X2 The Courier's Receiver clock is the source of the timing

signals. The signals are looped to the Transmit clock and

sent to your DTE over the RS-232 interface. This setting

is only used in those systems that require

synchronization of data flowing in both directions.

&YnBreak handling. This command allows you to send a break to

abort data transfer without disconnecting from the phone link.

&Y0 Destructive, don't send Break.

&Y1 Destructive, expedited (Default).

&Y2 Nondestructive, expedited.

&Y3 Nondestructive, unexpedited; modem sends Break in

sequence with data received from computer or terminal.

&ZC? Display the stored command string.

&ZC=sWrite the following command string s to NVRAM. The

command string may be up to 40 characters long; spaces are not

counted. This command can be used so that you can call

another modem without loading your communications

software.

After storing a command, you can program the voice/data

switch to execute the stored command string when pressed.

The following example assigns a command string that displays

the link diagnostics screen when you press the voice/data

switch.

AT&ZC=I6 <Enter>

COURIER HIGH SPEED MODEMS

Alphabetical Command Summary C-17

The function of the voice/data switch is determined by the set-

ting of Register S32, as described in Appendix G. Set the

voice/data switch function to execute stored command string by

setting Register S32 to 9 with the following command:

ATS32=9 <Enter>

Note that you can reset the voice/data switch at any time to one

of the other available functions. Additionally, you can

overwrite the stored command string with a new one at any

time.

Once you've stored your command string and set Register S32,

all you need to do is press the voice/data switch whenever you

want the command string executed.

&Zn=s This command stores up to ten numbers, where n is the position

0−9 in nonvolatile memory, and s is the phone number string.

The number-string may be up to 36 characters long, including

any Dial command options.

AT &Z2=555-6789 <Enter>

Do not include modem settings in the &Zn string. If the call

requires a special setting, insert it in the command string before

the DSn command. In the following example, &M0 (no error

control) is inserted before the Dial command:

AT&M0 DS2 <Enter>

NOTE: The &Zn=s command functions differently when Dial

Security is enabled. See Appendix D for more information.

&Zn?Display the phone number stored in NVRAM at position n

(n = 0−9).

COURIER HIGH SPEED MODEMS

C-18 Alphabetical Command Summary

PERCENT COMMAND SET

%AnCreate and configure security accounts. See Appendix D.

%BnRemotely configure the Courier's serial port rate. See Appendix

%B0 110 bps %B6 9600 bps

%B1 300 bps %B7 19,200 bps

%B2 600 bps %B8 38,400 bps

%B3 1200 bps %B9 57,600 bps

%B4 2400 bps %B10 115,200 bps

%B5 4800 bps

%CnRemote configuration control. See Appendix D.

%C0 Defer configuration. This is the default. Configuration

changes are deferred until the call is ended; they take

effect for ensuing connections. You do not need to enter

this command; it is the default unless you enter %C1 or

%C2.

%C1 Restore configuration. Use this command to cancel any

configuration changes made during remote access, and

restore the original configuration. However, commands

that have been written to NVRAM (with &W) will not be

restored to their previous settings. Additionally, if you

have forced immediate configuration changes (with

%C2), those changes cannot be reversed with %C1.

%C2 Execute configuration. Use this command to force

configuration changes to take effect immediately, during

the current connection. We recommend against forcing

immediate configuration changes unless absolutely

necessary, as this can result in an unreliable connection or

even a loss of connection.

%E=n Make security system edits. See Appendix D.

%E=1 Erase local access password.

%E=2 Erase autopass password.

%E=3 Erase passwords in accounts 0–9.

COURIER HIGH SPEED MODEMS

Alphabetical Command Summary C-19

%E=4 Erase phone numbers in accounts 0−9.

%E=5 Disable Account, Dialback, and New Number fields in

accounts 0−9 disabled.

%FnRemotely configure data format. See Appendix D.

%F0 No parity, 8 data bits.

%F1 Mark parity, 7 data bits.

%F2 Odd parity, 7 data bits.

%F3 Even parity, 7 data bits.

%L= Assign an account password as the local access password. See

Appendix D.

%N Works in conjunction with &Xn in synchronous mode. If the

modem is set so that it is the source of the Transmit clock timing

signals (&X0default), the %Nn commands set the computer or

terminal-to-modem V.25 bis clock speed. If the modem is set to

&X1, the computer is the source of the Transmit clock signals.

If %Nn is set to 0 or 1, you will receive an error message, since

they are not valid values. The %Nn rates are as follows:

%N0 Reserved %N6 9600 bps (default)

%N1 Reserved %N7 12.K bps

%N2 1200 bps %N8 14.4K bps

%N3 2400 bps %N9 16.8K bps

%N4 4800 bps %N10 19.2K bps

%N5 7200 bps

%Pn=Disables password security (n=0 or 1) when no character

follows the equal sign. See Appendix D.

%Pn=sSpecify the following password string (s) for viewing privileges

only (n = 0) or view and configuration privileges (n= 1). See

Appendix D.

%Pn?Display password n. See Appendix D.

%S=nObtain access to security accounts without disabling security.

See Appendix D.

COURIER HIGH SPEED MODEMS

C-20 Alphabetical Command Summary

%T Enables the modem, when off hook, to detect the tone

frequencies of dialing modems. %T is meant primarily for use

with network applications, but may also be integrated into

certain software programs. For example, %T could be used in a

security program to identify incoming tone security codes.

To enable %T, type ATH1 <Enter> to force the modem off hook.

Then type AT%T <Enter>.

To return the modem to Command mode, press any key or

drop the computer's or terminal's DTR signal. The modem

responds OK.

%V=PWnAssign the password in account n in your Courier modem’s

security as your autopass password. See Appendix D.

COURIER HIGH SPEED MODEMS

Dial Security D-1

APPENDIX D. DIAL SECURITY AND

REMOTE ACCESS OPERATIONS

Dial Security is designed to protect networks and data centers

from unauthorized access. The kind of security provided by the

Courier modem is different from other kinds of dial security

where software is used by the computer to control user access.

The Courier’s Dial Security is set up in the modem’s firmware,

so access is controlled from modem to modem.

Setting up this kind of security requires action at both the host

and remote modem sites. This appendix contains instructions

for both operations.

WARNINGS:

If you want to set up Security on your Courier modem, you

must complete the steps below in the order listed:

1. Set up your own security account:

•Set up your local access password

•Enable local access password protection

2. Set up remote user accounts.

3. Enable Dial Security.

You must set up your local access security information before

enabling Dial Security and allowing remote calls, as outlined

under Set Up Your Security Account in what follows.

Be sure to remember your local access password; if you enable

security and forget your local access password, you risk being

locked out of your system.

COURIER HIGH SPEED MODEMS

D-2 Dial Security

OVERVIEW

The Courier’s Dial Security allows you to configure up to 10

Security accounts. Each security account is stored in nonvolatile

memory (NVRAM) and may be set up in one of three ways:

•Automatic password access

•Prompted password access

•Password with Dialback protection

Autopass

Autopass is the term we use for the basic implementation of

Dial Security in the Courier modem. It is in effect whenever

Dial Security is enabled.

To use autopass alone, the following requirements must be met:

•Both host and remote modems must be U.S. Robotics

modems with Dial Security enabled.

•The connection must be under V.42 error control (both

modems must be set to &M4 or &M5).

When the remote modem is set for Dial Security, it automa-

tically includes an autopass password (configured by the

remote user to be compatible with the host modem’s security) in

its V.42 error control request. The host modem checks all the

enabled passwords in its security accounts for a match.

If the remote user has set up the modem with an invalid

password, the host modem returns an INVALID PASSWORD

message and hangs up.

If the remote user failed to enable Dial Security on the remote

Courier, the host Courier will not accept the call unless

prompting (below) is enabled on the host modem.

Prompting

While the use of autopass (above) is restricted to U.S. Robotics

Dial Security modems, prompting allows secured connections

with any remote modem whose user has been assigned an

allowed password. When prompting is enabled, and the host

modem doesn’t receive an autopass password, it prompts the

remote user for a password. The host modem checks the

received password against each of its active Security accounts.

COURIER HIGH SPEED MODEMS

Dial Security D-3

If the password is valid, a secure connection is completed.

If the password is invalid, the host modem prompts twice more

before disconnecting.

If there are no password attempts at the remote end, the host

modem times out after 60 seconds and disconnects.

NOTE: There is no prompting capability in synchronous mode.

Prompting is more flexible than autopass because it:

•doesn't require a remote modem to have U.S. Robotics

Dial Security.

•doesn't require a V.42 connection, so remote modems

without V.42 error control capabilities can connect.

Optional Dialback

Dialback offers an additional layer of security. When the host

modem receives a valid password that matches an account and

Dialback is enabled, the host first disconnects. The remote user

receives a NO CARRIER message. Then the host modem dials

back the remote modem.

Typically, the Dialback number is stored in the Security

account’s phone number field. However, if the security account

has been set up to allow a new number, the host prompts the

remote user for the new number before hanging up, and then

dials back.

In order to use dialback, Dial security and prompting must be

enabled.

WHAT THE HOST MODEM OPERATOR NEEDS TO DO

Complete the steps below in the order listed:

1. Set up your own Security account.

2. Set up Security accounts for your remote users.

3. Enable Dial Security.

4. Maintain Security accounts.

COURIER HIGH SPEED MODEMS

D-4 Dial Security

SET UP YOUR SECURITY ACCOUNT

Security accounts are set up via an AT command line structure,

rather than a screen format.

1. Set up your Security account using one of 10 accounts

(numbered 0−9). Each account has five possible fields, as

shown in the following table.

Password Account Dialback Allow New Dialback

Enabled Enabled Enabled Number Number

8 chars. max. YES/NO YES/NO YES/NO up to 37

ASCII 32-127 characters

case sensitive* (0−9)

BILL YYN1-419-555-5555

* If “BILL” is the password, “Bill” is an invalid entry.

Use the %An= command and format (below) to set up

accounts, where n is the account number, 0−9. The fields in

the above table are entered after the equal sign, each

separated by a comma, as in the following example for

account 0 with the password BILL.

WARNING: Do not insert spaces between commas or

between fields and commas. Spaces will invalidate the

command.

AT%A0=BILL,Y,Y,N,1-419-555-5555 <Enter>

This example instructs the modem to store the configuration

for account 0: password (BILL), account enabled (Y),

dialback enabled (Y), allow a new number (N), and the

dialback phone number.

NOTE: The %An= command is automatically written to

NVRAM and does not require an &W.

Some accounts may have fewer security options. The

following example sets the password (Judy) and enables

account 1 without any dialback options.

AT%A1=Judy,Y,,, <Enter>

COURIER HIGH SPEED MODEMS

Dial Security D-5

Each security function can be configured or modified

independently. If a field is to remain as is, just insert a

comma, as shown in the following command. It allows the

remote user to supply a new Dialback number different

from the one stored in the original account record.

AT%A0=,,,Y, <Enter>

2. Set up your local access password. This password protects

the Security accounts from unauthorized users. When this

protection is enabled, you cannot view, modify, or tamper

with the Security accounts unless you enter the correct local

access password. The local access password must be

chosen and protection must be enabled before Dial Security

is enabled.

In the following example, the local access password is the

same as the password in account 0.

AT%L=PW0 <Enter>

SET UP ACCOUNTS FOR REMOTE USERS

Once your account is configured and password protection has

been enabled, you can set up the remote user accounts. Use the

%An= command (using the same guidelines you used to set up

the system administrator’s account in Step 1 of the previous

section) to set up remote user accounts.

Once security accounts have been enabled, you are responsible

for communicating valid password information to your remote

users.

ENABLE DIAL SECURITY

Once you have completed the previous steps, you are ready to

enable Dial Security.

When you enable Dial Security, you must choose either

autopass or prompting as the security method. You must know

what types of modems remote users are using and set the Dial

Security parameters accordingly. Autopass is limited to U.S.

Robotics modems with Dial Security, but prompting is not.

COURIER HIGH SPEED MODEMS

D-6 Dial Security

1. Register S53 is the bit-mapped register used to enable Dial

Security. The &W command must be used to save Register

S53 settings to NVRAM. Otherwise, when the computer is

powered off and on again, or the modem is reset using

ATZ, it will default to S53=0, Dial Security disabled.

To enable Dial Security with autopass and local access

password protection, but without prompting, type the

following command:

AT S53.0=1 .2=1 &W <Enter>

The following command enables Dial Security with

autopass, prompting, and local access password protection.

AT S53.0=1 .1=1 .2=1 &W <Enter>

NOTE: Enabling local access password protection disables

the &Zn=s command that stores up to ten phone numbers.

Stored phone numbers occupy the same space in NVRAM

as the dialback numbers for Dial Security accounts, and

cannot be used when Dial Security is enabled.

If the local access password is not protected, the &Zn=s

command overwrites the corresponding Dial Security

dialback number. For example, the following command

overwrites the dialback number for account 5:

AT &Z5 = 555-8976 <Enter>

However, if the local access password is protected, and a

user tries to use the &Zn=s command, an ACCESS DENIED

message is displayed.

WARNING: Be sure DIP switch 10 is OFF so the modem

will load the settings stored in NVRAM. If someone sets

DIP switch 10 ON, the low performance template settings

(&F0) are loaded, and Dial Security is disabled. If this

should happen, reset DIP switch 10 to OFF, power off the

modem and power it back on, or reset the modem by

typing ATZ <Enter> so that the proper settings take effect.

COURIER HIGH SPEED MODEMS

Dial Security D-7

MAINTAIN SECURITY ACCOUNTS

Once the local access password is set and protected, the system

administrator is the only one who can access account

information. To modify or change account information, use the

%S= and %E= commands described next.

Account Access (%S)

Once Dial Security is enabled, you can access accounts by

entering the local access password using the %S= command,

which allows access to the accounts by disabling local security.

AT%S=(your local access password) <Enter>

NOTE: The modem echoes the local access password, which is

case sensitive. The system will accept an invalid password

entry, but will lock you out from the modem’s security

commands. For example, if the password is Bob, but you enter

BOB, an OK is displayed. However, if you try to type a security

command (for example, ATI10 <Enter> to view accounts), an

ACCESS DENIED message is displayed.

Account Status

Once access has been granted, you can view account

information by typing the I10 option of the Inquiry (I)

command:

ATI10 <Enter>

Remote users may only use this command during a remote

access session if local access security is disabled.

COURIER HIGH SPEED MODEMS

D-8 Dial Security

Erasing Account Information (%E)

Use the %E=n command to make system edits.

%E=1 Erase local access password.

%E=2 Erase autopass password.

%E=3 Erase passwords in accounts 0–9.

%E=4 Erase phone numbers in accounts 0−9.

%E=5 Disable Account, Dialback, and New Number

fields in accounts 0−9.

To edit or overwrite an individual account, or an individual

account field, use the %An= command described in Set Up Your

Security Account, earlier in this appendix.

Remote Configuration

Dial Security accounts may be configured remotely. See

Configuring Dial Security Remotely at the end of this appendix.

WHAT THE REMOTE CALLER NEEDS TO DO

When remote users want to call in to your Courier (assuming

you have enabled Dial Security), they must contact you to

obtain a valid password. They must also find out if they must

set the remote modem for auto answer (necessary if your

modem uses Dialback as a security method).

1. If the host modem security is set up, get a password from

the host modem operator. Passwords are case-sensitive, so

be sure to copy it down correctly.

If the host modem security is set up for prompting and the

host operator enables dialback for your account, skip to

Step 3.

2. For remote users with COURIER modems only. Set up security

on your modem, including an account that uses the

password the host asked you to use. Refer to Set up Your

Security Account, earlier in this appendix, for instructions.

COURIER HIGH SPEED MODEMS

Dial Security D-9

Then assign the password as your autopass password.

Enter the following command, where n is the number of the

account you set up):

AT %V=PWn <Enter>

You can check to see that you've correctly set up your

autopass password by typing the following command:

AT I10 <Enter>

Your autopass password appears in the right-hand column

below FORCED AUTOPASS.

Once the autopass password is set, enable your Courier

modem’s Dial Security with the following command:

ATS53.0=1 &W <Enter>

3. If Dialback is enabled at the host Courier site, set your

modem to answer the host modem when it disconnects and

dials back.

To set the modem to answer the Dialback call, set DIP

switch 5 OFF and reset the modem (ATZ <Enter>).

Alternatively, type the following command:

AT S0=1 <Enter>

4. Call the host modem.

5. When the call is completed, if you want to disable auto

answer, do one of the following:

•Set DIP switch 5 ON and reset the modem

(ATZ<Enter>).

•Type the following command:

AT S0=0 <Enter>

COURIER HIGH SPEED MODEMS

D-10 Remote Access

REMOTE ACCESS OPERATIONS

You can set a Courier modem so that someone at a remote

location can configure your modem.

This might be helpful if you have problems making a connection

with another modem. For example, if you have trouble

connecting with a bulletin board, you can allow the bulletin

board operator to dial in to your modem and view its

configuration settings. If necessary, the bulletin board operator

can send the Courier a configuration string that will make it

compatible with the bulletin board.

Another use might be for Dial Security administration when the

system administrator is unable to be at the host modem site. It

might be urgent, for example, to disable an account.

AT THE HOST COURIER SITE

There are two tasks required to set up remote access:

1. Set up password security.

2. Enable remote access.

Set Up Password Security

You can designate two passwords for remote access security,

each allowing a different level of access to the remote user. You

can assign one password that allows viewing privileges only,

whereby the host Courier's configuration can be remotely

viewed but not changed. You can assign another password that

allows both remote viewing and configuration privileges.

Remote access passwords can be up to eight alphanumeric

characters long, and are not case-sensitive.

%Pn Use the %Pn command to assign remote privileges.

%P0 Viewing privileges only

%P1 Viewing and configuration privileges

COURIER HIGH SPEED MODEMS

Remote Access D-11

To assign a password that allows viewing privileges only, use

the command format below:

AT%P0=[password] <Enter>

To assign a password that allows viewing and configuration

privileges, use the command format below:

AT%P1=[password] <Enter>

Disabling Password Security

If you want to disable an assigned password (and thereby dis-

able remote access security), use the following command

format:

AT%P0= <Enter>

AT%P1= <Enter>

WARNING: If you disable the %P1 password, a remote user

does not need to enter a password for configuration access.

Enable Remote Access

Set Register S41 for a value of 1 or greater. S41 is used to set the

number of allowable login attempts, as explained later. A

setting of zero allows no login attempts, and thus disables

remote access.

AT S41=1 <Enter>

NOTE: This method will not work if your modem is attached

to certain synchronous devices. Refer to Appendix F for more

information.

LED Indicator for Remote Access

The Courier's SYN status light indicator (LED) flashes to

indicate when it is in a remote access session.

COURIER HIGH SPEED MODEMS

D-12 Remote Access

AT THE REMOTE MODEM SITE

Remote configuration can be performed at any time during an

asynchronous connection. The user performing remote configu-

ration can use any modem; it does not have to be a U.S.

Robotics model.

1. Make sure the host Courier has been set for remote

configuration, as described earlier. Then establish a

connection. It does not matter which modem originates the

call.

2. After a connection has been established, send the following

escape sequence:

Pause four seconds,

type four tildes: ~~~~

and

pause another four seconds.

NOTE: You can change the escape sequence character

with Register S42. The pause duration (guard time) can be

modified with Register S43. (These values are set at the

host Courier modem.)

3. When the Courier begins its login sequence, the caller will

see a display similar to the following:

U.S Robotics Courier HST Dual Standard V.34 Fax

Remote Session

Serial Number 000000A000000001

4 . At this point, if password security is active, the caller is

prompted for the password.

Password (Ctrl-C to cancel)?.....

As described earlier in Password Security, entering the pass-

word assigned by the %P0 command allows viewing

privileges only. Entering the password assigned by the %P1

command allows viewing and configuration privileges.

Note that there is a 3-minute time limit for entering the

password.

COURIER HIGH SPEED MODEMS

Remote Access D-13

As mentioned earlier, if the number of unsuccessful login

attempts exceeds the set limit, the modem returns online

and refuses any further login attempts during the

remainder of that connection.

When a password is accepted, the Courier indicates that it

has entered Remote Access mode and the remote prompt

appears on the remote caller's screen.

Access Granted

Remote->

5. If password security is not active (no passwords have been

set or both passwords are disabled), the Courier automati-

cally enters Remote Access mode and the remote prompt

appears on the remote caller's screen.

Remote->

6. Once the remote access session has been established, keep in

mind that there is a 3 minute inactivity timer. If the modem

detects no activity for 3 minutes, it aborts the remote access

session and resumes a normal online connection.

Aborting the Request for Remote Access

If you want to abort the remote access login before you have

entered the password, return online by pressing <Ctrl>-C or

typing ATO <Enter>.

Remote Viewing and Configuration

Once you've gained remote access, you can communicate with

the host Courier as if you are entering commands at its attached

computer. Depending on your access privileges, you can use

the regular Courier AT commands.

If you have view privileges only (with %P0), you can use any of

the view (Inquiry) commands described in Chapter 6.

If you have view and configure privileges (set with %P1), you

can use any of the modem commands, except those commands

that cannot be used while online, such as the Dial command.

You can also use the remote configuration commands explained

later.

COURIER HIGH SPEED MODEMS

D-14 Remote Access

When you make remote configuration changes, the remote

prompt is altered to indicate that changes have been made. The

prompt will change from:

Remote->

Remote+>

If you restore the original configuration (with %C1, explained

next), the original prompt is also restored (back to Remote->),

indicating that the original configuration is intact.

By default, configuration changes do not take effect until the

connection is terminated (see %Cn). However, the new configu-

ration is immediately reflected on the information screens

(ATIn).

Remote Configuration Commands

There are some additional commands that are only executable

during a remote access session. These commands are as

follows.

%BnConfigure the Courier's serial port rate.

%B0 110 bps %B6 9600 bps

%B1 300 bps %B7 19,200 bps

%B2 600 bps %B8 38,400 bps

%B3 1200 bps %B9 57,600 bps

%B4 2400 bps %B10 115,200 bps

%B5 4800 bps

%CnConfiguration control.

%C0 Defer configuration. This is the default. Configu-

ration changes are deferred until the call is ended;

they take effect for ensuing connections. You do

not need to enter this command; it is the default

unless you enter %C1 or %C2.

COURIER HIGH SPEED MODEMS

Remote Access D-15

%C1 Restore configuration. Use this command to

cancel any configuration changes made during

remote access, and restore the original

configuration. However, commands that have

been written to NVRAM (with &W) will not be

restored to their previous settings. Additionally, if

you have forced immediate configuration changes

(with %C2), those changes cannot be reversed with

%C1.

%C2 Execute configuration. Use this command to force

configuration changes to take effect immediately,

during the current connection. We recommend

against forcing immediate configuration changes

unless absolutely necessary, as this can result in an

unreliable connection or even a loss of connection.

%FnConfigure data format.

%F0 No parity, 8 data bits.

%F1 Mark parity, 7 data bits.

%F2 Odd parity, 7 data bits.

%F3 Even parity, 7 data bits.

Password Commands

%Pn=Disables password security (n=0 or 1) when no

character follows the equal sign.

%Pn=sSpecify the following password string (s) for viewing

privileges only (n = 0) or view and configuration

privileges (n= 1).

%Pn?Display password n.

COURIER HIGH SPEED MODEMS

D-16 Remote Access

Command Format

When typing commands during the remote access session, no

delay between command strings is necessary. For example, you

can type the following commands without pausing after each

one:

•a password: ABCDEF <Enter>

•a configuration string: AT&H1&R2&W <Enter>

•and a request for an information screen: ATI5 <Enter>

The maximum number of characters between carriage returns is

40.

Ending a Remote Access Session

One of four commands ends a remote access session.

•<Ctrl>-C aborts the login procedure.

•ATZ resets the modem and terminates the connection.

•ATH terminates the connection.

•ATO or ends the remote access session, but the modems

remain online.

CONFIGURING DIAL SECURITY REMOTELY

The system administrator can configure host Courier security

account information with a Courier modem at a remote site

using the procedures described below.

NOTE: Before remote configuration is possible, the local

modem's remote access must be enabled, and a remote access

password that allows viewing and configuration privileges

must be assigned. For convenience, you may want to use your

local access password as your remote access password.

Dialing In From the Remote Site

1. From the remote site, connect to the host modem using Dial

Security. Once a connection is made, follow the instructions

for beginning a remote access session as described earlier in

this appendix.

COURIER HIGH SPEED MODEMS

Remote Access D-17

2. When remote access has been granted, use the %S=

command to access the Dial Security accounts.

3. If you wish, you can view account information by typing

the following Inquiry (I) command:

AT I10 <Enter>

4. Make any configuration changes and execute them

immediately by typing the following command:

AT %C2 <Enter>

5. To end the remote session and reactivate local access

security on the host modem, reset the modem by typing:

ATZ <Enter>

WARNING: If you do not use the ATZ command to end a

remote access session, local access security will remain

disabled at the host Courier site and anyone dialing in to

your modem for remote access will have access to the I10

screen and all Security accounts.

COURIER HIGH SPEED MODEMS

Troubleshooting E-1

APPENDIX E. TROUBLESHOOTING

You may occasionally encounter one of the problems listed here.

They are divided into three categories: Running the SDL.EXE

Upgrade Program, Before Establishing the Link, and During

Data Transfer.

Running the SDL.EXE Upgrade Program

Your modem . . .

Is indicating an error

Try running the SDL program at a lower serial port rate. If your

computer doesn’t have a 16550 UART, a slower serial port rate

can make all the difference.

You can also try running the program on a different PC. An

idiosyncracy of an off-brand PC or an uncommon version of

DOS may lock up the SDL program.

Before Establishing the Link

Your modem . . .

Doesn't answer the phone or go off hook to dial a number

Review your communications software manual to see what

Data Terminal Ready (DTR) operations your software requires.

Then check to see if DIP switch 1 is set correctly. Also, check to

make sure your terminal or computer is sending a DTR signal

via the RS-232 interface.

Doesn't respond OK when you type AT <Enter>

1. Make sure you're typing in either upper case or lower case

letters, not a combination, and that you press the Enter key.

2. If you're using a computer, make sure it is in Terminal

mode. This is a communications software function. See

Testing the Modem in Chapter 2.

COURIER HIGH SPEED MODEMS

E-2 Troubleshooting

3. Check to see that your terminal or software is set to the

correct bit rate and word length (7 bits with or without a

parity bit, or 8 bits and no parity). If you're using a

computer, make sure your software is set to the correct

communications port.

4. Check that DIP switch 8 is ON, for command set

recognition. If the switch is OFF, power off the modem, set

the switch ON, and power on the modem again. Try typing

AT <Enter> again.

5. Check that DIP switch 3 is ON, for result code display, and

that DIP switch 2 is OFF, for verbal result codes. If not,

change the switch(es) and type ATZ <Enter>. Or type

whichever of these commands is needed:

ATQ0 <Enter> (to enable the message)

ATV1 <Enter> (to display a verbal message)

6. Review your communications software manual to see what

Carrier Detect (CD) operations your software requires.

Then check to see if DIP switch 6 is set correctly.

7. A rare condition is that your terminal or computer reverses

the send/receive functions at the RS-232 interface. See your

equipment documentation.

Displays double characters

Both your modem's and software's local echo are on. You can

turn your software's local echo off. Or turn the modem's echo

off by either resetting DIP switch 4 and sending the modem the

ATZ command, or by sending the modem the ATE0 command.

Your computer . . .

Reacts as though a data link has been established, but no call has

been received

DIP switch 6 is set ON at the factory for Carrier Detect (CD)

override, but your system may require that the override be

turned OFF.

Review your terminal's manual or your communications

software manual to see what CD operations are required. Then

check to see if DIP switch 6 is set correctly.

COURIER HIGH SPEED MODEMS

Troubleshooting E-3

When the modem is in Answer mode, it acts as though a Carriage

Return has been entered, but nothing has been typed at the keyboard

Your software may be misreading signals from the modem as it

automatically sends a Carriage Return and a Line Feed before

and after the RING and CONNECT messages. Sending the

Quiet mode command, ATQ1 <Enter>, should solve the

problem.

Both modems . . .

Exchange carrier signals, but fail to establish a communications link

1. If you have a fax modem, make sure it is in the correct

mode, fax or data, depending on whether the connection is

to be made with a facsimile device or a data modem. See

Fax Operations in Chapter 5 for information on switching

between Fax and Data modes.

2. Asynchronous operations: Check to make sure the proper

bit rate, word length, parity and number of Stop bits have

been selected. Synchronous operations: review the link

instructions in Appendix F. If you've set the modem to the

correct configuration, the problem may be with the

synchronous adapter or with the system you're trying to

call.

3. Check to see that your modem is at the correct Bn setting to

connect with either an HST modem (B1 setting) or V.32 terbo

modem (B0 setting). Type ATI4 for a display of the

Courier's current settings and, if necessary, send the

modem the correct setting.

4. If your modem is attempting to answer a V.32 call, you may

need to lengthen the extra V.32 answer tones. See S28 in

Appendix B.

5. Depending on your model, make sure the modem at the

other end of the line is HST compatible, V.32 terbo

compatible at 14.4K bps, or V.32 compatible at 9600 bps,

V.22 bis-compatible at 2400 bps, Bell 212A-compatible at

1200 bps, or Bell 103-compatible at 300 bps. These are the

common signaling standards for full duplex dial-up

network transmission in the U.S.

COURIER HIGH SPEED MODEMS

E-4 Troubleshooting

6. Make sure your modem's connection rate setting, &Nn is

correct for the call. If the connection rate is locked at a

speed (&N1−&N14) different from the calling modem's, the

Courier hangs up. The factory setting of &N0, variable link

operations, allows the two modems to negotiate the highest

possible connection rate.

7. If none of the above corrects the problem, it's likely that the

quality of the phone connection is poor and that the other

modem is missing the signals your modem is transmitting.

The variable quality of phone line connections may be due

to any number of conditions in the phone service's

equipment or the current environment. Try several calls,

and if you still can't get through, try calling another modem.

If the second modem accepts your call, the problem may lie

with the modem you first tried to call.

During Data Transfer

Your screen displays . . .

Only brackets

Check to make sure that both modems are set to the same bit

rate, word length, parity and number of Stop bits. If the settings

are correct, the problem may be with the phone line. Try the

following measures:

1. Try placing the call again. The phone company routes even

local calls differently each time you call.

2. Try calling a different modem to see if the problem persists.

The problem may be with the modem you first tried to call.

Random or garbage characters

Check to make sure that both modems are set to the same bit

rate, word length, parity, and number of Stop bits.

If the modem is set to a fixed serial port rate (&B1) and your

software is fixed at 19.2K, 38.4K, 57.6K, or 115.2K bps, the

reason may be one of the following:

1. Your computer may not support the high rate. If this is the

case, fix your software rate at 9600 bps and disable high-

speed V.32 terbo modulation: ATS34=3 or ATS34 .0=1 .1=1.

COURIER HIGH SPEED MODEMS

Troubleshooting E-5

2. If you use memory-resident programs (TSRs), they may be

interfering. Try disabling them before you run your com-

munications software. The same is true of disk-caching

programs.

3. Check to see that your software and the modem are set for

the same kind of flow control, either hardware or software.

Some communications programs also require that you dis-

able the kind you are not using.

Double characters

Your modem's online local echo is on and the remote modem is

also echoing. The only way to correct this is to bring the

modem back to Command mode (wait one second without

transmitting data, type +++, wait another second). Then type

the command to turn off your online echo (ATF1 <Enter>).

If DIP switch 9 is OFF (factory setting), the modem hangs up

when it returns to Command mode, and you'll have to call

again. If DIP switch 9 is ON, the modem maintains its

connection. You can return it back online by typing ATO

<Enter>.

IF YOU STILL HAVE PROBLEMS

The problems described above are by far the most common ones

that users encounter. If the suggestions we've given don't clear up

your difficulties, try the following:

1. Review the manual carefully to see if you've missed

something.

2. Call or visit your modem dealer. Chances are your dealer

will be able to give you the assistance you need. This is

much more efficient and time-saving than returning the

modem to U.S. Robotics.

3. If your dealer can't help you, refer to the Customer Service

Access Card provided in this package. This card lists

several important U. S. Robotics numbers.

4. If you must return your modem to us, the Service

Representative you talk to will give you a Return Materials

Authorization (RMA) number. Modems without an RMA

number will not be accepted.

COURIER HIGH SPEED MODEMS

E-6 Troubleshooting

5. If you do return the modem to us, please use the following

procedures.

a. Ship the unit, postage paid, in its original container. If

the original container is not available, pack the modem

carefully in a strong box of corrugated cardboard with

plenty of packing material.

b. Be sure to include your RMA number inside the

package, along with your name and address. Put your

return address and your RMA number on the shipping

label as well.

c. Ship the well-packed modem to the following address.

Technical Support Department

U.S. Robotics, Inc.

8100 North McCormick Boulevard

Skokie, Illinois 60076-2999

d. Please note that U.S. Robotics will not accept packages

sent COD, so be sure to send the modem postage paid.

e. U.S. Robotics will repair your modem and return it to

you via United Parcel Service.

COURIER HIGH SPEED MODEMS

Synchronous Operations F-1

APPENDIX F. SYNCHRONOUS AND

DEDICATED AND LEASED LINE OPERATIONS

SYNCHRONOUS APPLICATIONS

Synchronous mode is required for users who need to call, or

receive calls, from a Host computer of a large network. The

Host is usually a mainframe. There are two ways the Courier

can operate in synchronous mode:

•Selecting the ITU-T standard V.25 bis protocol, which

formats data in HDLC or character-oriented frames.

This method is used by mainframe operators and

synchronous terminal users.

V.25 bis acts as an interface between the mainframe and

modem, sending synchronous responses. An

asynchronous device or a "dumb" terminal is used to

configure the modem before it dials out in synchronous

mode.

•Dedicating a PC as a synchronous device by installing

the proper hardware and software so it can

communicate with a mainframe. The modem is

configured and dials out in asynchronous mode, then

switches to synchronous mode once a connection is

made.

NOTE: HST modulation is not supported for synchronous

communications.

GENERAL REQUIREMENTS

Courier modems in asynchronous mode adapt to many condi-

tions of remote asynchronous modems. But synchronous

connections to a mainframe require strict adherence to specific

operating parameters. If you are operating a terminal designed

for a particular network, you probably need only set the Courier

properly before calling or answering.

COURIER HIGH SPEED MODEMS

F-2 Synchronous Operations

NOTE: The term DTE in the following discussion means Data

Terminal Equipment, the end-to-end equipment involved in

data communications. DTE denotes your terminal or computer

and the remote computer.

What You Need to Know

The network's communications management staff can supply

information on the following requirements:

•The protocol needed for your calls

•The software support needed to log into the network;

for example, a specific communications package or

interface board

•The phone number, if you will be calling instead of

answering

•Any restrictions about when you can call

The RS-232 Interface

Transmit and Receive synchronous timing pins are required at

the RS-232 interface. You'll need either pin 15 or pin 24 for

Transmitter timing signals, depending on whether the modem

(pin 15) or the DTE (pin 24) generates the signals. You'll also

need pin 17, for Receiver timing signals. If you're building your

own cable, review the RS-232 Interface, in Appendix B.

Protocol Compatibility

The devices at both ends of the link must use the same protocol.

These protocols format data into blocks or frames and add

control information.

If the modem is in V.25 bis mode, the link protocol must be

HDLC (High-Level Data Link Control), or character-oriented. If

the modem is in Online Synchronous mode it may use HDLC,

character-oriented, or another protocol determined by the

mainframe manufacturer.

COURIER HIGH SPEED MODEMS

Synchronous Operations F-3

Data Rate Synchronization (&Xn)

During synchronous operations, transmit and receive clocks at

both ends of the phone link control the precise timing of the

data flow. The communications equipment at the remote DTE

and your modem and DTE must all handle the data at the same

speed.

The transmit clock timing signals setting, &Xn, determines

whether the modem or DTE will generate the timing signals.

For Online synchronous operations, the source for this setting

must be the same on both systems. See Connection Rate (%Nn,

&Nn) later in this appendix.

Most Online synchronous users will require the default setting,

&X0.

&X0 The Courier is the source of the Transmit clock timing

signals and sends them to your DTE over the RS-232

interface. The DTE rate will follow the connection rates.

Default.

&X1 The DTE is the source of the Transmit clock timing

signals and sends them to the Courier over the RS-232

interface. This setting is used typically in leased line

multiplexed operations. (Multiplexors divide the phone

channel so that the channel carries several calls at the

same time.)

The DTE ignores the Courier's clock timing signals and

negotiates the DTE and connection rates.

&X2 The Courier's Receiver clock is the source of the timing

signals. The signals are looped to the Transmit clock and

sent to your DTE over the RS-232 interface. This setting

is only used in those systems that require

synchronization of data flowing in both directions.

COURIER HIGH SPEED MODEMS

F-4 Synchronous Operations

V.25 BIS REQUIREMENTS

V.25 bis is an ITU-T standard that uses the HDLC or character-

oriented protocols to format data.

Before you attempt to connect to a synchronous network, you

must configure the modem in command (asynchronous) mode

by using either an asynchronous device or dumb terminal. V.25

bis commands are used for this purpose. The computer or

terminal sends V.25 bis commands to the modem to ready the

line for synchronous transmission. Once the synchronous

connection is made and the modem is in synchronous mode,

V.25 bis commands are no longer necessary and are ignored.

The modems on each end of the connection are transparent to

the host computers or terminals.

To set the modem, follow the instructions in Chapter 4,

Command Set Usage. Commands begin with a required AT

prefix and end with a required Carriage Return, which we

denote with the symbol <Enter>. For example, the following

command causes the modem to set the connection rates, enable

normal result codes, enable auto answer, select HDLC as a link

protocol, and save the settings to NVRAM. Spaces have been

added only for readability.

AT &N0 %N6 X0 S0=1 &M7 &W <Enter>

Be sure that DIP switch 10 is OFF so that the modem loads the

settings you've stored in nonvolatile random access memory

(NVRAM) when it powers on. Until you customize your own

settings, the settings in NVRAM are the same as the &F1

Hardware Flow Control template.

Connection Rate (&Nn, %Nn)

There are three phases to obtaining and maintaining a

connection rate during synchronous communication.

Clock Speed Control

The first phase is in deciding where the clock speed will be

determined. (See Data Rate Synchronization, above.)

COURIER HIGH SPEED MODEMS

Synchronous Operations F-5

Offline Host/Modem Clock Speed

The second phase involves the data rate between the host

computer or terminal and its modem during offline mode. The

%N command is used to set the clock speed between the

modem and host, but this speed is only during offline mode,

before the synchronous connection is made.

The %Nn command works in conjunction with &Xn. If the

modem is set so that it is the source of the Transmit clock timing

signals (&X0default), the %Nn commands set the computer or

terminal-to-modem V.25 bis clock speed. If the modem is set to

&X1, the computer is the source of the Transmit clock signals.

If %Nn is set to 0 or 1, you will receive an error message, since

they are not valid values. The %Nn rates are as follows:

%N0 Reserved %N6 9600 bps (default)

%N1 Reserved %N7 12.K bps

%N2 1200 bps %N8 14.4K bps

%N3 2400 bps %N9 16.8K bps

%N4 4800 bps %N10 19.2K bps

%N5 7200 bps

Online Connection Rate

The &N command sets the data rate during the synchronous

connection.

If &Nn is set for 2−10, the modem ignores the %Nn rate and

follows the &Nn rate to set the Online connection rate. The

&Nn rates are as follows:

&N0 Variable (default) &N6 9600 bps

&N1 Reserved &N7 12K bps

&N2 1200 bps &N8 14.4K bps

&N3 2400 bps &N9 16.8K bps

&N4 4800 bps (terbo−to−terbo only)

&N5 7200 bps &N10 19.2K bps

(terbo−to−terbo only)

COURIER HIGH SPEED MODEMS

F-6 Synchronous Operations

Recommended Settings

When the connection is made and the data rate is determined,

host/modem rates may change dramatically to match the

connection rate (when in online synchronous mode, the modem

is transparent on the line). To avoid this dramatic rate

switching (which can be hard on some computers), we

recommend that the modem be set with a fixed rate between the

computer or terminal and modem (%Nn) and that the

connection rate (&Nn) be set to the same rate.

Result Codes (Xn)

The Courier displays normal or extended synchronous result

codes, depending on the setting of the Xn command. By

default, the modem is set to X1 for extended result codes. To

change to normal result codes, set the modem to X0.

The normal result codes return messages such as VAL or INV

(VALID or INVALID), whereas the extended codes offer

explanationsINVPS (INVALID Parameter Syntax Error).

Automatic Answering (S0=1)

When the Courier is operating in V.25 bis mode, it ignores the

DIP switch 5 setting, which controls Auto Answer. To set the

modem to automatically answer incoming calls, set the modem

to S0=1, so it answers on the first ring. You can substitute a

higher value. See the S-Register summary in Appendix B.

Suppressing Auto Answer

To disable Auto Answer, set the modem to answer on zero

rings, S0=0.

Choosing a Synchronous Protocol (&Mn)

Once the &Xn, %Nn, &Nn, Xn, and S0 commands are

configured, you must use the &Mn command to choose the

HDLC or character-oriented link protocol so that your

synchronous software can properly format its commands.

&M6 Use the character-oriented protocol for synchronous

communications.

COURIER HIGH SPEED MODEMS

Synchronous Operations F-7

The Courier and the remote modem must use the same

eight-bit data format. The character length must be 7

bits and either ODD or EVEN parity (ODD is preferred),

or 8 bits and NO parity.

&M7 Use the High Level Data Link Control (HDLC), an

ITU-T standard for synchronous communications.

HDLC ignores parity.

V.25 bis Commands and Result Codes

Commands

•CIC (Connect incoming call)

Instructs the modem to answer an incoming call.

•CRN (Call request using number provided )

Instructs the modem to dial the number following this

command.

Example:

CRN18001234

•CRS (Call Request with memory location)

Instructs the modem to dial a number stored in

memory.

Example:

CRS3

•DIC (Disregard incoming call)

Instructs the modem to disregard an incoming call

overrides auto answer for this call.

•PRNn (Program number)

Stores a number in NVRAM.

Example:

PRN3; 18001234

•RFN (Request list of forbidden numbers)

Instructs the modem to list the numbers with which the

modem is unable to connect.

•RLN (Request list of stored numbers)

Instructs the modem to list those numbers previously

stored in NVRAM.

COURIER HIGH SPEED MODEMS

F-8 Synchronous Operations

Dial Options

0−9Digits

&Flash

:Wait for dial tone

>(Greater Than) separator

<Pause

=(Equal Sign) separator

PPulse

TTone

.(Period) separator

-(Minus) separator

Result Codes

•SFI (Call failure indication) with optional parameters:

-CFAB (Abort call)

-CFCB (Local modem busy)

-CFET (Engaged tone)

-CFFC (Forbidden call)

-CFNS (Number not stored)

-CFNT (Answer tone not detected)

•CFRT (Ring tone)

•CNX (Connect)

•LS (List of numbers)

•LSF (List of forbidden numbers)

•LSN (List of stored numbers)

•INC (Incoming call)

•INV (Invalid) with optional parameters:

-INVMS (Message syntax error)

-INVCU (Command Unknown )

-INVPS (Parameter syntax error )

-INVPV (Parameter value error )

•VAL (Valid)

COURIER HIGH SPEED MODEMS

Synchronous Operations F-9

Commands and Result Codes NOT Supported

•CRI (Call request with identification number)

•PRI (Program identifier)

•RLI (Request list of identification numbers)

•RLD (List of delayed call numbers)

Hanging Up

Since the modem cannot accept commands once it is connected

in synchronous mode, you cannot use the ATH (hang up)

command or the +++ escape sequence.

The only way for the modem to disconnect is to drop its DTR

signal. This is normally done with software. However, if the

modem is initially set to S32=6 when it is in asynchronous

mode, the modem will reset when the voice/data switch is

pressed, thus dropping DTR.

Returning to Asynchronous Mode

Once you've completed a communication session, you can

switch between synchronous and asynchronous modes by

flipping DIP switch 10 OFF (factory settings, asynchronous

mode) and then ON (NVRAM settings, synchronous mode if

the modem is set to &M6 or &M7).

The modem cannot switch between synchronous and

asynchronous while a call is connected.

ONLINE SYNCHRONOUS REQUIREMENTS

Although personal computers do not usually support

synchronous communications, they can be dedicated to do so.

If you have a personal computer you must find out what

hardware and software you need before setting the Courier for

synchronous calls.

COURIER HIGH SPEED MODEMS

F-10 Synchronous Operations

The Synchronous Adapter Card

You will probably have to purchase and install a synchronous

adapter card. These cards are multifunction boards that

provide the following functions:

•A synchronous port from the DTE to the modem

•One or more synchronous protocols. Be sure to find out

which protocol the Host mainframe requires before you

purchase an adapter.

•Additional software functions. For example, you need

to identify the type of computer or terminal you are

using to the mainframe software. You will most likely

also have to specify your applicationthat is, identify

the mainframe resources you want to use.

Setting the Modem

When the modem is set to Online Synchronous mode, it remains

in command (asynchronous) mode until it makes a synchronous

connection with a remote modem. Upon connection, the

Courier enters synchronous mode and sends synchronous

timing signals to your DTE.

Because the modem will not accept commands when it is in

synchronous mode, you will have to configure it in

asynchronous mode before trying to connect to a synchronous

network.

NOTE: Be sure that DIP switch 1 is OFF (factory setting). The

Data Terminal Ready (DTR) override must be OFF so that the

Courier detects when the DTE raises and lowers the DTR signal.

To set the modem, follow the instructions for issuing commands

in Chapter 4, Command Set Usage. Commands begin with a

required AT prefix and end with a required Carriage Return,

which we denote with the symbol <Enter>.

For example, the following command causes the modem to set

the modulation, the connection rate, and choose a timing

source. Spaces have been added only for readability.

AT B0 &N0 &X0 <Enter>

COURIER HIGH SPEED MODEMS

Synchronous Operations F-11

Modulation/Connection Rate (Bn, &Nn)

Use the following guidelines for your Courier type. V.Fast

Class does not support synchronous mode.

V.32 terbo modems

If the modem is connecting with another U.S. Robotics V.32

terbo modem, set both modems to B0 and to a variable

connection rate, &N0. The modems will connect at the highest

possible rate.

If the Courier V.32 terbo is to connect with a V.32 modem, set

the Courier to B0 and try a variable connection rate first, &N0.

If that doesn't work, try a fixed connection rate of &N6 (9600

bps) or &N3 (2400 bps).

Modems in HST mode

HST modulation for synchronous communications is not

supported.

Dual Standard modems

Set the Dual Standard modem to B0. Try a variable connection

rate setting (&N0) first. If that doesn't work, you may have to

set a fixed connection rate, for example, &N6 (9600 bps).

NOTE: If your modem is set to a fixed rate, and the remote

modem is not set to the same rate, your modem hangs up.

Connection Rate (&Nn)

Use this command to set variable or fixed rates at the link

interface. The default is &N0, variable rate. The Courier

negotiates with the remote modem for the highest possible

connection rate, depending on the capabilities of the remote

modem. If &N0 does not work, try a fixed rate.

NOTE: The modem is not capable of connecting at 21.6K bps in

synchronous mode.

When you set the modem to a fixed rate, it will only connect if

the remote modem is operating at the same rate. If not, your

modem hangs up.

COURIER HIGH SPEED MODEMS

F-12 Synchronous Operations

The fixed rate options are as follows:

&N0 Variable rate &N6 9600 bps

&N1 Reserved &N7 12K bps

&N2 1200 bps &N8 14.4K bps

&N3 2400 bps &N9 16.8K bps

&N4 4800 bps (terbo−to−terbo only)

&N5 7200 bps &N10 19.2K bps (terbo−to−terbo only)

Generating Clock Timing Signals

The &Xn setting specifies whether the Courier or your DTE

generates the Transmit clock timing signals for a synchronous

call. Most users will require the default setting, &X0. See Data

Rate Synchronization (&Xn), earlier in this appendix, for more

information.

Dialing Out

The modem's stored command feature (&ZC=s) allows you to

configure the modem for a synchronous connection and to dial

out to the Host computer by just pressing the voice/data

switch. Below are our recommended procedures.

1. If your communications software isn't running, load the

program and put the computer in Terminal mode, as

described in Chapter 2. Terminal mode allows you to send

AT commands directly to the modem.

2. Using the guidelines in Chapter 4, store a command string

(&ZC=s) that configures the modem according to the Host

computer's requirements. In addition, include the &M1

command, to have the modem enter synchronous mode,

followed by the appropriate Dial string. The following is an

example:

AT &ZC = &F &X1 &M1 DT5551234 <Enter>

In the example, &F sets the modem's defaults as those of the

&F0 template settings, while &X1, which specifies the

computer as the synchronous timing source, is the only non-

default setting used besides synchronous mode (&M1).

Any non-default settings should follow the &F command.

The Dial command should be the last entry before the

Carriage Return.

COURIER HIGH SPEED MODEMS

Synchronous Operations F-13

3. Set the voice/data switch to option 9, so that the modem

executes the stored command string when you press the

switch. Type the following:

ATS32 = 9 <Enter>

NOTE: If you usually use the voice/data switch for another

purpose, you can include the execute stored command

option (S32 = 9) in the stored command string. However,

the total number of characters in the string may not exceed

30.

If S32=9 is used with the stored command string, it over-

writes any other S32 option. Once the communication

session is over, you will have to reset S32 if you want to

select another option.

4. Press the voice/data switch when you want to connect with

the synchronous Host computer. You need not have your

communications software loaded at the time.

5. After the call, restore the modem to asynchronous oper-

ations by powering it off and on again.

Answering

To configure the modem for Answer mode using the voice/data

switch, follow the instructions in the previous section, Dialing

Out, but with these modifications:

•Insert S0 = 1 in the stored command, Step 2. This sets

the modem to Auto Answer.

•Omit the Dial string shown in the same step (DT and

phone number).

If you don't wish to use a stored command and the voice/data

switch, send the modem the appropriate configuration string,

ending with &M1. The following command adapts the dial-out

command example. Note again that all non-default settings

follow the &F command.

AT &F S0=1 &X1 &M1 <Enter>

The modem responds automatically to an incoming call, enters

synchronous mode and, in this case (because it is set to &X1),

waits for synchronous timing signals from your DTE.

COURIER HIGH SPEED MODEMS

F-14 Synchronous Operations

Hanging Up

The modem remains online until the remote modem disconnects

or your software causes the DTE to drop the Data Terminal

Ready signal (DTR). The Courier sends the NO CARRIER

result code if result codes are enabled, and returns to

asynchronous Command mode.

Testing and Inquiry Commands

The modem testing commands (&Tn) and inquiry commands

(In) cannot be used when the modem is operating in

synchronous mode.

ENABLING REMOTE ACCESS

Because synchronous equipment cannot use AT commands to

configure modems, a special function was designed so the

modem can receive AT commands remotely. To do this, the

modem must be placed in remote access mode with the

voice/data switch.

Press and hold down the voice/data switch while powering on

the modem. Pressing the switch during power-on causes the

modem to perform its normal self-test, enable Auto Answer,

enable Remote Access (by changing the S41 setting to 1), and

disable password security.

WARNING: If you enable remote access by pressing the

voice/data switch while powering on the modem, previously

set passwords will be erased.

COURIER HIGH SPEED MODEMS

Dedicated and Leased Line Operations F-15

DEDICATED AND LEASED LINE OPERATIONS

The following operations apply in installations where the

modem's phone line is not part of a public-access switched

telephone network. Instead, the modem is connected to a

special user-installed telephone line or a line that is leased from

the telephone company. These lines are often referred to as

dedicated (to a pair of modems) or private lines.

In both types of installation there is a continuous point-to-point

connection between two modems. No dialing of phone

numbers is required. The modems may be in either Smart or

Dumb mode (determined by the position of DIP switch 8).

The User-Installed or Leased Telephone Line

User-installed lines are most commonly 2-wire lines, similar to

the 2-wire lines that connect residential phones to the public

switched network.

If you are leasing a line from the telephone company, request a

2-wire line, the type of line the modem is designed to work

with. If the telephone company only makes a 4-wire line

available, you'll need a 4-wire to 2-wire converter at each end of

the connection. If the phone company does not install the con-

verters, you will have to supply them.

For optimal operations, we recommend that the physical length

of these lines not exceed 5 miles.

Setting the Modem

If the Courier is set to &L1, as described in what follows, and

the remote AT-compatible modem has a comparable setting,

they automatically connect when they are powered on. They

also reconnect, without any operator intervention, if a

disturbance on the line is severe enough to break the

connection.

COURIER HIGH SPEED MODEMS

F-16 Dedicated and Leased Line Operations

Set the modem as follows:

1. Set your terminal or communications software to the rate at

which you want the modems to communicate. For

example, use a terminal/software setting of 19.2K bps and,

if both modems have the capability, they will connect at

14.4K bps. The following instructions assume that you are

familiar with the guidelines on using the &B and &H

commands (Chapter 3) and the &W command (Chapter 3).

2. Send the modem the following command:

AT &B1 &S2 &H1 &L1 &W <Enter>

&B1 fixes the modem's computer interface rate at the same

serial port rate you selected when setting up your

communications software. &S2 causes the modem to send a

Clear to Send (CTS) signal only after it sends the Carrier

Detect (CD) signal, that is, only after it connects with the

remote modem. (See the note that follows.) &H1 enables

hardware (CTS) flow control.

&L1 forces the modems off hook at power on and enables

them to re-establish the connection should it be broken.

&W writes the settings to nonvolatile memory (NVRAM) as

power-on defaults.

NOTE: We recommend using the &S2 setting to delay CTS

until after the connection is made, as a precaution. If the

modems are in the process of connecting or reconnecting,

the Courier interprets any keyboard data entry, including

an accidental key stroke, as a key-press abort, and hangs up.

Delaying CTS until after carrier detection prevents this from

happening, for example, if you are typing data to the remote

modem when the modems momentarily disconnect and

begin to reconnect. However, you have to set the modem

for hardware flow control, &H1.

If your software or machine does not support Clear to Send

(CTS), don't include &S2 and &H1 in the command string as

suggested above. Follow the Transmit Data flow control

(&H) guidelines in Chapter 3. But keep in mind that if the

modems fail to connect or reconnect, the reason could be a

key-press abort.

COURIER HIGH SPEED MODEMS

Dedicated and Leased Line Operations F-17

3. Set the modem to load NVRAM settings at power-on, DIP

switch 10 OFF. It does not matter if the modem is in Dumb

or Smart mode (DIP switch 8).

4. Decide which modem is to be the calling modem and which

the answering modem. Set the answering modem to Auto

Answer, DIP switch 5 OFF, and the calling modem to Auto

Answer suppressed, DIP switch 5 ON.

5. Power off and power on the modems. This initiates the new

DIP switch settings and loads the power-on defaults,

including &L1. The modems go off hook and establish the

connection.

NOTE: If the modems cannot restore the connection and you

could not set the modem to &S2, the reason could be a key-

press abort. If the problem persists, however, you may need to

call your telephone company to have them check your line.

COURIER HIGH SPEED MODEMS

Additional Operations G-1

APPENDIX G. ADDITIONAL OPERATIONS

CONTENTS

HST Cellular

Voice/Data (External Modems Only)

Hewlett Packard 3000 Installations

MI/MIC Operations (External Modems Only)

COURIER HIGH SPEED MODEMS

G-2 Additional Operations

CELLULAR OPERATIONS

This function applies to Dual Standard HSTs only. HST cellular

modems can be used to answer or originate calls, but are

proprietary. They can only connect with other U.S. Robotics

Dual Standard modems with HST cellular capabilities.

To enable cellular mode, load the &F3 template settings by

typing the following command:

AT &F3 <Enter>

To save this as your power-on/default setting, type this:

AT &F3 &W <Enter>

The &F3 command sets the serial port rate to 19,200 bps, and

formats the data for 8 bits, no parity and one stop bit. The ini-

tialization string sent to the modem by loading this template is

shown below.

AT B1 X7 S10 = 30 &B1 &L2 &H1 &I0 &R2

•B1enables HST modulation

•X7—displays extended result codes including NO DIAL

TONE, RINGING, NO ANSWER, and BUSY messages

•&B1locks the serial port rate so that it remains higher

than the connection rate.

•S10=30sets the modem to wait 3 seconds after loss of

carrier before hanging up.

•&L2enables cellular mode

•&H1enables hardware flow control

•&I0disables software flow control

•&R2sets the modem so it sends received data to the

computer or terminal when the Ready To Send (RTS)

signal is high, only if the computer or terminal supports

RTS.

COURIER HIGH SPEED MODEMS

Additional Operations G-3

The modem uses the U.S. Robotics proprietary HST cellular

protocol to make connections. The call starts at 1200 bps, a V.42

error control connection is negotiated, then the modem switches

to 4800 bps and begins measuring the line conditions.

Depending on line conditions, the modem decreases or

increases its connection rate, to a minimum speed of 300 bps

and a maximum of 12K bps. If a connection terminates before

data transfer is completed, the system tries to re-establish the

link and complete the transfer.

If a large number of blocks are being resent (shown by the ARQ

LED flashing randomly; some software displays the blocks

retransmitted in the file transfer window), you may want to

reduce the packet size by doing the following:

1. Be sure DIP switch 9 is ON so that the modem remains

online if it receives +++.

2. If DIP switch 9 is OFF, switch it to ON and reset the modem

by issuing the ATZ command.

3. Send the modem the escape sequence by typing +++ so that

the transmission is interrupted, and wait 1 second.

4. Type AT S33=1 to reduce the packet size.

5. Then type ATO so that the modem returns online and

continues to transmit.

NOTE: HST cellular connections can only be made with other

U.S. Robotics modems in HST cellular mode. The modem

cannot be used to place a voice or data call to another phone or

modem when it is in this mode.

COURIER HIGH SPEED MODEMS

G-4 Additional Operations

VOICE/DATA (EXTERNAL MODEMS ONLY)

The voice/data switch is located on the modem's front panel.

While the switch's primary function is to toggle back and forth

between voice and data communications, this feature also

allows you to perform other functions at the touch of a switch.

Use Register S32 to select these functions, as shown in Table

G.1.

Additionally, the Courier modem allows you to use the

voice/data switch to set the modem for remote access if

attached to certain synchronous devices. This is described in

Enabling Remote Access in Appendix F.

NOTE: Use the voice/data switch when the modem is in

Command mode (offline). If you press the switch while the

modem is online, the modem hangs up and returns a NO

CARRIER result code.

VOICE/DATA OPERATIONSS32=1, S32=2 OR AT COMMANDS

When you install the Courier, you have the option of plugging

your phone into the second modular jack of the modem so it's

available for voice calls. You can also switch between the phone

and modem during a call.

If the remote modem has handset exclusion, you can change

from voice to data and back again, with or without issuing a

command.

Handset exclusion means that if the modem is using the phone

line, your phone (handset) is automatically disconnected.

However, if you keep the handset off hook, once you hang up

the modem the handset takes over the phone line and you can

use voice communications again. If the remote user does not

have handset exclusion, you may not be able to switch back to

voice mode successfully once you have switched to Data mode.

The following instructions describe how to toggle voice/data

communications with the switch. This is followed by

instructions for doing the same thing with AT commands. If the

remote user does not have a switch, he or she can follow the

instructions for using the appropriate AT command.

COURIER HIGH SPEED MODEMS

Additional Operations G-5

Voice/Data SwitchS32=1, S32=2

1. Phone the other user to establish the bit rate, parity, word

length and number of Stop bits the other person's modem

accepts. (Both modems should be offline, in Command

mode.)

You and the other user must also agree on which modem

will go off hook in Originate mode and which in Answer

mode. The Courier is factory set to go off hook in Originate

mode, S32=1. The Answer modem should have S32 set to 2.

NOTE: If the stored command string command has been

used (&ZC=s), the modem will default to S32=9, which

executes the stored command string when the voice/data

switch is pushed.

Either party's device can be the originate or answer modem;

it doesn't matter who made the phone call. But one modem

must first enter Originate mode and the other then enter

Answer mode.

2. Without hanging up the phone, press the voice/data switch.

If S32 is set to 2, Answer mode, press the voice/data switch

immediately after the remote user forces the remote modem

off hook in Originate mode.

3. The other party should force the remote modem off hook in

Answer mode by pressing the switch.

If yours is the Answer modem (S32=2), the other party

should press the voice/data switch immediately before you

do so.

4. If the remote modem has handset exclusion, the remote user

should also keep the phone off hook in order to switch back

to voice later. If the remote modem doesn't have handset

exclusion, you can try to switch back to voice later. Or, you

both can hang up your phones as soon as the modems go off

hook.

COURIER HIGH SPEED MODEMS

G-6 Additional Operations

Software CommandsATD, ATA

If your voice/data switch is set for a function other than

voice/data operations and you don't wish to change it, use AT

commands.

1. Call the other user to establish the bit rate, parity, word

length and number of Stop bits the other person's modem

accepts. Determine which modem will originate and which

will answer.

2. If you are to originate the connection, type the following

command:

ATD <Enter>

NOTE: Be sure the modem is not set to X2, X4, X6 or X7, or

it will return the NO DIAL TONE result code and hang up.

3. The other party must then have the remote modem go off

hook in Answer mode. The following command is used to

do this:

ATA <Enter>

4. If the remote modem also has handset exclusion, leave both

phones off hook in case you wish to switch back again to

voice after your data transfer. If the remote modem doesn't

have handset exclusion, switching back to voice may not be

successful. If you don't want to switch back to voice later,

hang up both phones as soon as the modems go off hook.

COURIER HIGH SPEED MODEMS

Additional Operations G-7

ALLOWABLE VOICE/DATA SWITCH FUNCTIONS

Use Register S32 to set the voice/data switch for the function

you desire. The default is S32=1pressing the switch forces the

modem off hook in Originate mode. Pressing the switch when

you power on the modem causes it to perform a power-on self-

test. See Table G.1S32 Functions below.

NOTE: Some of the applications listed below require some sort

of preconfiguration. Review the Chapter/Appendix referenced

before using the Voice/Data switch function.

S32 Value Voice/Data Switch Function Related Command

0Disabled _

1Voice/DataOriginate Mode (Default*)ATD (Appendix G)

2Voice/DataAnswer Mode ATA (Appendix G)

3Redial Last Number ATDL (Chapter 4)

4Dial Number Stored at position 0 ATDS0 (Chapter 4)

5Auto Answer On/Off Toggle ATS0=0 or 1 (Chapter 4)

6Reset Modem ATZ (Chapter 4)

7Initiate Remote Digital Loopback AT&T6, S16=8

(Appendix H)

8Busy Out Phone Line Toggle _

9Execute Stored Command (Default*)AT&ZC=s (Chapter 4,

Appendix F, G)

*The modem is shipped from the factory set at S32=9. If a command string has

been stored (&ZC=s), the modem executes the stored command string when the

voice/data switch is pushed. If no command string is stored, the modem still

reports that S32=9, but actually behaves as if it is set to S32=1, Originate mode.

Table G.1S32 Functions

COURIER HIGH SPEED MODEMS

G-8 Additional Operations

HEWLETT PACKARD INSTALLATIONS

During error control connections, the Courier recognizes the

ASCII ENQ/ACK characters exchanged between many Hewlett

Packard host computers and their terminals. The HP host sends

the terminal an ENQ character at predefined intervals, and

sends no more data until the terminal responds with an ACK

character.

Courier modems manage this ENQ/ACK protocol so that

communication is speeded up, thereby enabling HP terminals to

achieve high speeds on dial-up lines. Special flow control

settings, using the &I command, are required for HP users.

These settings apply to ARQ connections only and to Courier

modems set to either B0 or B1. Disregard other Courier flow

control commands.

Set the Courier to Host mode if it is attached to the host

computer, or to Terminal mode if it is attached to a terminal, as

follows:

Host mode AT&I3 <Enter>

Terminal mode AT&I4 <Enter>

COURIER HIGH SPEED MODEMS

Additional Operations G-9

MI/MIC OPERATIONS (EXTERNAL MODEMS ONLY)

DESCRIPTION

Mode Indicate/Mode Indicate Common (MI/MIC) closure is

required by some installations whose existing hardware does

the dialing. The modems do not Auto Dial.

In these situations, the modem must be forced off hook in

Originate mode. This is done by shorting (closing) two of the

pins (not Tip and Ring) in the phone connector. The modem is

then ready to go online and accept data when it connects with

the number dialed by the system equipment.

Courier modems are shipped with MI/MIC disabled, that is, for

normal use. To set the modems for MI/MIC closure, you must

do two things: physically set jumpers on the modem’s printed

circuit board, and enable bit 5 of Register S34 (ATS34=32 or

ATS34.5=1). We recommend you then write that setting to

NVRAM as a power-on default.

Once you've set Register S34, have the system force the modem

off hook by closing the MI/MIC leads in the phone line

connector. The modem's OH (Off Hook) status light, or LED,

goes on when the modem goes off hook.

SETTING THE MI/MIC JUMPERS

You'll have to dismantle the modem case to set the two jumper

switches on the printed circuit board, as follows:

1. Power off the modem and disconnect all of its cables.

2. Turn the modem upside down. Remove the two square

vinyl feet near the back of the case, on either side of the

bottom label's DIP switch diagram. Be careful to put the

vinyl feet aside, upside down, where they won't become

stuck to another object.

3. Remove the two Phillips screws located in the wells beneath

the vinyl feet.

4. Gently pry off the plastic volume slide-switch cover.

5. Raise the back end of the case bottom until it is at about a

60° angle; lift it away from inside the front of the modem.

Put the case bottom aside.

COURIER HIGH SPEED MODEMS

G-10 Additional Operations

6. Locate the voice/data switch at the front of the modem.

Lift up and remove the modem (printed circuit board),

carefully easing the voice/data switch out of its opening in

the front panel.

7. Turn the modem rightside up and locate jumper switches J4

and J6, near the power-adapter socket. Use Figure G-1 as a

guide.

Figure G-1Courier Modem Board

8. The jumpers are black shunts that cover two out of three

upright metal contacts. As shown in the figure, set the

jumpers so they cover the two contacts on each switch that

are closest to the front panel. The third contact on each

switch is exposed.

9. Replace the modem in the case top: ease the voice/data

switch into the opening in the front panel and make sure the

back of the board rests on the locator pins at the rear (from

which you removed the screws).

COURIER HIGH SPEED MODEMS

Additional Operations G-11

10. Connect the modem's RS-232, power and phone cables, in

that order (see chapter 2). Be sure the phone cable is

plugged into the jack closest to the center of the modem

the jack represented by the wall jack icon on the case bottom

label.

CAUTION: When you power on the modem there will be

potentially hazardous voltage, particularly near the phone

jacks. Do not touch the board when the power is on.

11. Power on the modem. Try MI/MIC closure. Check to see

that the Off Hook (OH) status light goes on. If you dialed a

number, listen for an answer tone from the remote modem.

Then drop the DTR signal. The modem should go on hook

and the OH status light should go off.

12. When you are sure the equipment is working correctly,

disconnect the modem’s RS-232, power and phone cables,

and replace the bottom of the modem case. Ease the two

nibs near the front corners into their openings in the front of

the case top, guide the rectangular slot over the volume

switch, and ease the back of the case bottom into place.

Replace the two screws, the two vinyl feet, and the volume

slide-switch cover.

TROUBLESHOOTING

You may find that the modem does not respond to MI/MIC

closure, which you can monitor by observing the LED. Or the

modem may fail to go back on hook when the computer or

terminal drops the Data Terminal Ready (DTR) signal. The

probable reason for either of these conditions is that your phone

equipment reverses MI/MIC polarity.

It's possible to solve this problem by reversing the modem's

MI/MIC wiring. You'll have to dismantle the modem case

again and reset the two jumper switches on the printed circuit

board, as follows:

1. Lift off the jumpers from J4 and J6. Reverse the positions

shown in Figure G-1. That is, on each switch, cover the

center and rightmost contacts. Make sure the jumpers cover

two contacts on each switch, or you'll disable the MI/MIC

function.

COURIER HIGH SPEED MODEMS

G-12 Additional Operations

2. Replace the modem in the case top: ease the voice/data

switch into the opening in the front panel and make sure the

back of the board rests on the locator pins at the rear (from

which you removed the screws).

3. Reconnect the modem's RS-232, power and phone cables, in

that order. Be sure the phone cable is plugged into the jack

closest to the center of the modemthe jack represented by

the wall jack icon on the case bottom label.

CAUTION: When you power on the modem there will be

potentially hazardous voltage, particularly near the phone

jacks. Do not touch the board when the power is on.

4. Power on the modem. Try MI/MIC closure again. Check

to see that the Off Hook (OH) status light goes on. If you

dialed a number, listen for an answer tone from the remote

modem. Then drop the DTR signal. The modem should go

on hook and the OH status light should go off.

5. If closure is not working properly, review the steps in this

section. Be sure the jumper switches are in the reverse

position of those in Figure G-1. If you still have problems,

there may be a problem with the phone cable. Or there may

be a problem with your hardware.

6. When the equipment is working correctly, disconnect the

modem’s RS-232, power and phone cables, and replace the

bottom of the modem case. Ease the two nibs near the front

corners into their openings in the front of the case top, guide

the rectangular slot over the volume switch, and ease the

back of the case bottom into place. Replace the two screws,

the two vinyl feet, and the volume slide-switch cover.

COURIER HIGH SPEED MODEMS

Modem Testing H-1

APPENDIX H. MODEM TESTING

Testing is available with the &T command or Register S16. All

loopback testing conforms to ITU-T Recommendation V.54.

Earlier U.S. Robotics high speed modems, however, did not

perform the &T test repertoire.

Only one test can be performed at a given time. If you send a

test command while the modem is in test mode, you'll receive

an ERROR message.

NOTE: Testing is not available when the modem is in

synchronous mode: &M1, &M6, &M7.

TESTING WITH &T

The tests supported through the &T command include analog

loopback, digital loopback and remote digital loopback. Users

can key in their own data during testing, or use the modem's

internal test pattern and error detector.

In all cases, disable error control before testing. If the modem is

detecting errors and retransmitting the affected data, your

results will be invalid.

During testing, the MR status light flashes.

Ending a Test&T0, S18

Issuing the &T0 command terminates a test. Alternatively, set

S18=10. When the 10 seconds are up, the modem automatically

ends the test and returns to Command mode. If the test was

Analog Loopback, the &T0 command hangs up the modem. If

the test was Digital or Remote Digital Loopback, issue an ATH

command to hang up the modem, or an ATZ command to hang

up the modem and reset it to its defaults.

NOTE: If you use the S18 test timer, but in the process of

testing you issue an ATZ command, S18 resets to zero and the

timer is disabled. You cannot store a value for S18 in

nonvolatile memory; its power-on and reset default is always

zero.

COURIER HIGH SPEED MODEMS

H-2 Modem Testing

ANALOG LOOPBACK&T1, &T8

This test checks the operation of the modem's transmitter and

receiver. Data flow is shown in Figure H-1.

Figure H-1Data Flow During Analog Loopback

There are two analog loopback options. The first, &T1, involves

your typing data that you can verify at your screen.

The second option, &T8, is an internal self-test that does not

involve the keyboard or screen. It isolates the modem from the

computer interface to give you a more specific result.

NOTE: Dual Standard modems must be set to B0 (default) or

tested at 2400 bps or lower to avoid HST asymmetrical

modulation at higher speeds.

&T1

1. If you are testing an HST or Dual Standard modem, set

your terminal or software to 2400 bps.

2. The modem must be in Command mode. If you wish, set

3. Send the modem the following command:

AT &M0 &T1 <Enter>

The modem disables error control, enters analog loopback

(AL) mode, and sends a CONNECT message. The MR

status light flashes.

COURIER HIGH SPEED MODEMS

Modem Testing H-3

4. Type recognizable data so that you can verify it when it is

looped back to the screen.

5. End the test. If you set S18, the modem automatically stops

the test at the timeout, exits AL mode and responds OK.

If you didn't set Register S18, wait one second and type +++

to bring the modem back to Command mode. If DIP switch

9 is OFF, the modem also hangs up and ends the test.

If DIP switch 9 is ON, type AT&T0 to end the test. Or send

either ATH or the command that resets the modem, ATZ.

The latter two commands end the test and hang up the

modem. The modem responds OK. If the modem sends an

ERROR message, you have issued an invalid command.

6. If there were no errors, reset the modem to &M4, for error

control, unless you've issued the ATZ reset command.

NOTE: If the modem is in online-command mode, that is,

still connected to a remote modem, and you send it an &T1

or &T8 command, it drops the call, enters AL mode, sends a

CONNECT result and waits for loopback characters.

&T8

This AL option causes the modem to send an internal test

pattern to its transmitter and loop it back to the receiver. An

internal error detector counts any errors and, when the test is

ended, sends the number of errors or 000 (no errors) to the

screen.

Since you don't type anything during this test, and the modem

does not send anything to the screen, this option verifies only

the modem. If there are no errors but your problem continues,

it may be at the computer interface.

1. If you are testing an HST or Dual Standard modem, set

your terminal or software to 2400 bps.

2. The modem must be in Command mode. If you wish, set

COURIER HIGH SPEED MODEMS

H-4 Modem Testing

3. Send the modem the following command:

AT &M0 &T8 <Enter>

The modem disables error control and enters AL mode.

The MR status light flashes. The modem sends its internal

test pattern to the transmitter, and loops the pattern back to

the receiver. You will not see any data on your screen.

4. End the test. If you set S18, the modem automatically stops

the test at the timeout. If you didn't set Register S18, type

AT&T0 to end the test. Or use ATH or the command that

resets the modem, ATZ. Both of the latter end the test and

hang up the modem.

The modem hangs up and returns a three-digit code,

followed by OK. A code of 000 indicates no errors were

found. A code of 255 indicates 255 or more errors. An

ERROR message indicates that you issued an invalid

command.

5. If there were no errors, reset the modem to &M4 for error

control unless you issued the ATZ command.

&T2

This option is reserved.

DIGITAL LOOPBACK&T3

If your modem has passed the AL test, this test can help you

locate a problem with a remote modem or the telephone

channel. Figure H-2 shows the data flow during DL testing.

Figure H-2Data Flow During Digital Loopback

COURIER HIGH SPEED MODEMS

Modem Testing H-5

NOTE: This test requires the modem to establish a connection

and return to online-command mode in response to the +++

escape code. DIP switch 9 must be set ON so that the modem

does not hang up on receipt of the escape code. After you

change the switch, issue ATZ to the modem to initiate the new

setting.

As with AL testing, HST and Dual Standard modems should be

tested at 2400 bps or lower.

1. Set the modem to &M0, to disable error control. HST and

Dual Standard modems should be set to 2400 bps or lower

to avoid asymmetrical modulation at higher speeds.

Establish a connection with the remote modem.

2. Bring the modem back to Command mode with the +++

escape code. Then send it the AT&T3 command. The

modem enters DL mode and the MR status light flashes.

3. The remote user should type a short message. It will be

looped back by your modem's transmitter for verification

on the remote screen. You will not see the message or any

other data.

4. When the remote user has completed the test, issue the

AT&T0 command to end the test. Or send either ATH or

the command that resets the modem, ATZ. The latter two

commands end the test and hang up the modem. The

modem responds OK. If the modem sends an ERROR

message, you have issued an invalid command.

5. Reset DIP switch 9 OFF if you normally use the factory

default. Reset the modem to &M4 unless you used the reset

command, ATZ.

&T4, &T5

The &T4 option causes the modem to grant a remote modem's

request for a Remote Digital Loopback test.

The &T5 option cancels &T4, and the modem fails to recognize

such a request. This is the default so that your modem isn't

subject to another user calling and tying up your modem

without your permission.

COURIER HIGH SPEED MODEMS

H-6 Modem Testing

REMOTE DIGITAL LOOPBACK&T6, &T7

This test, like the local digital loopback test, verifies the

condition of both modems and the phone link. Data flow is

shown in Figure H-3.

Figure H-3Data Flow During Remote Digital Loopback

The request for and granting of Remote Digital Loopback

testing requires that both modems use ITU-T V.22 standard

signaling. The test must be performed at 2400 bps or lower. If the

remote modem does not have the capability or is not set to

respond (&T4), you will get an ERROR result code.

As with Analog Loopback, there are two Remote Digital

Loopback options. If you select &T6, you send keyboard data to

the modem and verify it when it is returned over the phone

lines and to your screen. If you select &T7, the modem sends its

internal test pattern and returns an error count to your screen.

NOTE: Both test options require the modem to establish a

connection and return to online-command mode in response to

the +++ escape code. DIP switch 9 must be set ON so that the

modem does not hang up on receipt of the escape code. If

necessary, set the switch ON and then issue the ATZ command

to the modem to initiate the new switch setting.

&T6

1. Set the software to 2400 bps or lower. Set the modem to

&M0. If you wish, set the S18 timer.

Establish a connection with the remote modem. If you

haven't already done so, arrange with the remote user to

cooperate with your testing and, if necessary, set the remote

modem to acknowledge the RDL request. For example,

older U.S. Robotics high speed modems need to be set to

S16=8.

COURIER HIGH SPEED MODEMS

Modem Testing H-7

2. Bring the Modem back to Command mode with the +++

escape code. Send it the AT&T6 command. The modem

enters RDL mode and the MR status light flashes.

3. Type a short message. It will be looped back to your

modem by the remote modem and to your screen for

verification. (The remote user will not see your data.)

4. End the test. If you set Register S18 the modem

automatically ends the test when the test timeout is reached.

If you didn't set S18, type AT&T0 to end the test. Or send

either ATH or the command that resets the modem, ATZ.

The latter two commands end the test and hang up the

modem. The modem responds OK. If you issue an invalid

command, the modem sends an ERROR message.

Data errors indicate a problem with the remote modem or

the phone link. If you have not performed analog loopback

testing with your modem, the problem may also lie with

your modem.

5. Reset DIP switch 9 OFF unless you normally set that switch

ON, and issue ATZ to the modem to initiate the new

setting. Reset the modem to &M4 unless you used the reset

command, ATZ.

&T7

This test option causes the modem to send an internal test

pattern through the Remote Digital Loopback. An internal error

detector counts any errors and, when the test is ended, sends

the number of errors or 000 (no errors) to the screen.

You don't need to type anything during this test. The modem

sends only its final error count to your screen.

1. Set the software to 2400 bps or lower. Set the modem to

&M0. If you wish, set the S18 timer.

Establish a connection with the remote modem. If you

haven't already done so, arrange with the remote user to

cooperate with your testing and, if necessary, set the remote

modem to acknowledge the RDL request. For example,

older U.S. Robotics high speed modems need to be set to

S16=8.

COURIER HIGH SPEED MODEMS

H-8 Modem Testing

2. Bring the modem back to Command mode with the +++

escape code. Then send it the AT&T7 command. The

modem enters RDL mode and the MR status light flashes.

The modem sends its internal test pattern to the remote

modem, which loops it back to your modem. You will not

see the data on your screen.

3. End the test. If you set S18, the modem automatically stops

the test when the timer times out. If you didn't set Register

S18, type AT&T0 to end the test. Or send either ATH or the

command that resets the modem, ATZ. The latter two

commands end the test and hang up the modem. The

modem responds OK. If you issue an invalid command, the

modem sends an ERROR message.

When you terminate the test, the modem returns a three-

digit code, followed by OK. A code of 000 indicates no

errors were found. A code of 255 indicates 255 or more

errors.

If you've performed an Analog Loopback and know your

modem is working properly, errors indicate a problem with

either the phone connection or the remote modem.

4. Reset DIP switch 9 OFF unless you normally operate with it

ON. Issue an ATZ command to initiate the new switch

setting. Reset the modem to &M4 unless you've sent it the

ATZ reset command.

TESTING WITH REGISTER S16

functions:

Bit Value Function

0 1 Analog Loopback (AL)

1 2 Dial Test

2 4 Test Pattern

3 8 Remote Digital Loopback (RDL)

COURIER HIGH SPEED MODEMS

Modem Testing H-9

NOTE: Earlier U.S. Robotics modems require bit 3 to be

enabled in order to grant RDL to a remote modem. The modem

now requires its default &T4 setting instead. To perform RDL

with a U.S. Robotics modem that does not use the &T test

repertoire, that modem should be set to S16=8 before it can

grant RDL testing.

ANALOG LOOPBACK (AL)S16=1D

As with the &T AL test, do not attempt this test under error

control. HST and Dual Standard modems should be tested at

2400 bps or lower, to avoid asymmetrical modulation at higher

speeds.

To use the modem's Test Pattern (S16, bit 2) instead of typing

your own data, see Test Pattern−S16=4 later in this appendix.

1. To initiate testing, type AT&M0S16=1D. The modem

disables error control, enters AL mode and sends a

CONNECT result code. The MR status light flashes.

2. Type data to the modem for the modem to transmit, loop to

its receiver, and output to the screen. An alternative is to

use the Test Pattern, described later.

3. End the test by not typing anything for one second, then

typing three pluses (+++), and waiting another second. This

forces the modem back to Command mode. If DIP switch 9

is OFF, the modem exits AL mode and returns to Command

mode. If DIP switch 9 is ON, the modem maintains the con-

nection when it receives the +++ escape code. Issue the

ATH command to end AL mode.

4. Reset the modem to Data mode, S16=0, and error control

(&M4), or issue the ATZ (reset) command.

DIAL TESTS16=2

The Dial Test is used for factory testing the frequencies of tone

values. When S-Register 16 is set to 2 and a single tone is dialed

(e.g., ATD7 <Enter>), the modem continues to transmit that

tone until you type another Carriage Return.

COURIER HIGH SPEED MODEMS

H-10 Modem Testing

TEST PATTERNS16=4

The test pattern can be used instead of your typed data during

Analog Loopback (AL) or Remote Digital Loopback (RDL),

using &T commands or S16. The test pattern is available at all

speeds. At 300 bps, the modem's serial port rate must be fixed

(&B1) and the link rate fixed at 300 bps (&N1). At rates over

9600 bps, just set the modem for a fixed serial port rate (&B1).

To use the test pattern during AL testing with S16, type the

following command. The test pattern is sent through the

loopback.

AT&M0S16=5D

To use the test pattern during RDL testing with S16, type the

following command:

AT&M0S16=12

To use the test pattern with the &T AL or RDL tests, insert the

test pattern command, S16=4, before issuing the test command.

The first of the following commands initiates AL, the second

RDL:

ATS16=4&T1

ATS16=4&T6

The test pattern alone (ATS16=4) is used for testing equipment

and the phone line. When S16 is set to 4, the modem transmits

the test pattern upon connection with a remote modem.

Ending Testing with the Test Pattern

Pressing any character key cancels all test pattern tests and

hangs up the modem. If you used Register S16, be sure to reset

error control defaults, for example, ATZ or AT&M4S16=0.

REMOTE DIGITAL LOOPBACKS16=8

Responding Modem

The responding modem must be ready to act on the Courier's

RDL request. U.S. Robotics high speed modems should be set

to &T4. If they do not have &T testing capability, they should

be set to S16=8.

COURIER HIGH SPEED MODEMS

Modem Testing H-11

Initiating Modem

1. If DIP switch 9 is OFF, set it ON so that it does not hang up

on receipt of the +++ escape code. Issue an ATZ command

to initiate the new switch setting.

2. Set the software to 2400 or 1200 bps. The ITU-T-specified

RDL signals are defined only for connections at 2400 or 1200

bps.

3. Disable error control by setting the modem to &M0. Then

establish a connection with the remote modem.

4. Bring the modem back to Command mode by sending it the

escape code: one second of no data, three pluses (+++), and

another second of no data.

5. When the OK result code appears, send the modem the

following command:

ATS16=8 O

The modem enters RDL mode (S16=8), the MR status light

flashes, and the modem goes back online (O command).

Then it transmits the ITU-T-defined RDL signals, causing

the remote modem to enter RDL mode.

6. Type any data at the keyboard. (Or send the test pattern.)

7. To end the test, send the modem the +++ escape code again

to bring it back to Command mode.

8. When the modem sends the OK result, reset the modem to

Data mode with the following command:

ATS16=0

The modem signals the responding modem that RDL

testing is over. Terminate the call as you normally would,

and reset the modem to its normal error control setting,

&M4 or &M5.

Or, if you wish to resume data transmission with the remote

modem, add the O command to the ATS16=0 string to

return the modem online.

COURIER HIGH SPEED MODEMS

H-12 Modem Testing

Keep in mind, however, that error control is disabled.

Because error control is negotiated during the connection

sequence, its status cannot be changed until the modem is

back on hook and in Command mode.

COURIER HIGH SPEED MODEMS

Software Upgrades I-1

APPENDIX I. SOFTWARE UPGRADES

The Courier V.34 modem is software upgradable. You can

download upgrades from the USR Bulletin Board Service (BBS)

to obtain maintenance fixes or new features.

We suggest you retain a copy of the most recent upgrade on

disk so you can download it to your modem again, should the

modem lose its code for any reason.

The software download program requires DOS version 3.0 or

higher and may be run from the DOS shell under Microsoft

Windows.

Call the USR BBS

1. Call the USR BBS:

ATDT 708 982 5092 <Enter>

2. Unless you are running an ASCII-based communications

program, answer YES at the graphics prompt when you

connect to the BBS.

3. Press Enter with each prompt until you come to the main

menu.

Download the Upgrade File

1. At the command line of the main menu, type F (File) and

press Enter. Select area 5 (Courier) from the file area menu

The most recent zipped files will display.

2. Use the Enter key to scroll through the list and use the

spacebar key to highlight a file.

Scroll through the list and highlight the file named

USRSDL.EXE. Press Enter when it is highlighted to flag the

file for download.

3. Press Enter to go back to the main menu.

4. At the command line on the main menu, type D and press

Enter to initiate a download.

COURIER HIGH SPEED MODEMS

I-2 Software Upgrades

5. Answer the download prompts according to your system

requirements. The file will be downloaded to the directory

specified in your communications software.

6. When the file transfer is complete and you are ready to

leave the BBS, type G (Goodbye) from the main menu.

Upgrade your Modem

NOTE: Your modem must be turned on for the following

operation.

1. At the DOS prompt of the directory where your copy of the

file has been downloaded, type USRSDL and press Enter.

The zipped file will self-extract several files onto your

computer hard disk.

2. Type SDL and press Enter.

The .EXE file checks the code embedded in itself. If there is

a problem, an error message appears and the operation is

terminated. If you receive an error message, download the

file again.

3. A screen appears with default COM port information.

If you want to alter the defaults, use the guidelines below.

/c=nEnter this command to select one of four

predefined COM ports on an IBM-compatible PC.

Valid entries for n are 1, 2, 3, and 4. The default is

COM 2. If you change the COM port setting, a

compatible IRQ will be displayed.

/i=nEnter this command to set up a custom port. It

specifies which IRQ (interrupt request) the COM

port will use to interrupt the processor for service.

Valid entries for n are 2, 3, 4, 5, and 7. The default

is IRQ 3.

/a=nEnter this command to specify a port address,

where n is the hexadecimal address of a custom

port only.

COURIER HIGH SPEED MODEMS

Software Upgrades I-3

/b=nEnter this command to specify the bit rate at which

the COM port will communicate with the modem.

Valid entries for n are 9600, 19200, 38400, 57600,

and 115200. The default is 57600 bps.

/q This command allows you to shut off most of the

screen display as the program upgrades your

modem code for batch-mode execution. You will

not be prompted to accept settings.

/? This command displays a help screen.

4. A prompt asks if you want to “Download Using These

Settings? (Y/N).” Type Y if you want to continue. Type N

if you want to abort the operation.

NOTE: This is the only opportunity you will have to abort

the operation.

5. Once you have accepted the settings, the software

download will begin. During this operation, the Modem

Ready (MR) LED goes out.

6. When the operation has successfully completed, the

“Modem reports download successful” message displays

and the MR LED lights up again.

Troubleshooting

If your modem indicates an error, try running the SDL program

at a lower serial port rate. If your computer doesn’t have a

16550 UART, a slower serial port rate can make all the

difference.

You can also try running the program on a different PC. An

idiosyncracy of an off-brand PC or an uncommon version of

DOS my hang up the SDL program.

COURIER HIGH SPEED MODEMS

Glossary J-1

APPENDIX J. GLOSSARY

Cross-references in the following definitions are printed in boldface.

Adaptive Speed Leveling (ASL)

Courier V.32 bis and V.32 terbo modems detect improved line

conditions and shift upward again to the next higher speed.

The modems at both ends of the connection adapt

independently, each detecting and adjusting to line conditions.

ASL keeps the modems online, always operating at the highest

possible speed, and constantly ensuring data integrity.

Analog Loopback

A modem self-test in which data from the keyboard is sent to

the modem's transmitter, modulated into analog form, looped

back to the receiver, demodulated into digital form, and

returned to the screen for verification.

Analog Signals

Continuous, varying waveforms such as the voice tones carried

over phone lines. Contrast with digital signals.

Answer Mode

A state in which the modem transmits at the predefined high

frequency of the communications channel and receives at the

low frequency. The transmit/receive frequencies are the re-

verse of the calling modem which is in Originate mode.

Application (application program)

A computer program designed to perform a specific function,

such as a word processor or a spreadsheet.

ARQ

Automatic Repeat Request. A general term for error control

protocols which feature error detection and automatic retrans-

mission of defective blocks of data. See HST, MNP, and V.42.

COURIER HIGH SPEED MODEMS

J-2 Glossary

ASCII

American Standard Code for Information Interchange. A 7-bit

binary code (0's, 1's) used to represent letters, numbers, and

special characters such as $, !, and /. Supported by almost

every computer and terminal manufacturer.

Asymmetrical Modulation

A duplex transmission technique which splits the communi-

cations channel into one high speed channel and one slower

channel. During a call under asymmetrical modulation, the

modem with the greatest amount of data to transmit is allocated

the high speed channel. The modem with less data is allocated

the slow, or back channel (450 bps). The modems dynamically

reverse the channels during a call if the volume of data transfer

changes.

Asynchronous Transmission

Data transmission in which the length of time between

transmitted characters may vary.

Because the time lapses between transmitted characters are not

uniform, the receiving modem must be signaled as to when the

data bits of a character begin and when they end. The addition

of Start and Stop bits to each character serves this purpose.

Auto Answer

A feature in modems enabling them to answer incoming calls

over the phone lines without the use of a telephone receiver.

Auto Dial

A feature in modems enabling them to dial phone numbers over

the phone system without the use of a telephone transmitter.

Baud Rate

The number of discrete signal events per second occurring on a

communications channel. Although not technically accurate,

baud rate is commonly used to mean bit rate.

COURIER HIGH SPEED MODEMS

Glossary J-3

Bisync

Binary Synchronous Control. An earlier protocol developed by

IBM for software applications and communicating devices

operating in synchronous environments. The protocol defines

operations at the link level of communications, for example, the

format of data frames exchanged between modems over a

phone line. See Protocol, HDLC, SDLC.

Binary Digit

A 0 or 1, reflecting the use of a binary numbering system (only

two digits). Used because the computer recognizes either of

two states, OFF or ON. Shortened form of binary digit is bit.

Bit Rate

The number of binary digits, or bits, transmitted per second

(bps). Communications channels using telephone channel

modems are established at set bit rates, commonly 300, 1200,

2400, 4800, 9600, and 14400.

BPS

The bits (binary digits) per second rate.

Buffer

A memory area used as temporary storage during input and

output operations. An example is the modem's command

buffer. Another is the Transmit Data flow control buffer used

for flow control and to store copies of transmitted frames until

they are positively acknowledged by the receiving modem.

Byte

A group of binary digits stored and operated upon as a unit. A

byte may have a coded value equal to a character in the ASCII

code (letters, numbers), or have some other value meaningful to

the computer. In user documentation, the term usually refers to

8-bit units or characters. 1 kilobyte (K) is equal to 1,024 bytes or

characters; 64K indicates 65,536 bytes or characters.

Call Indicate

A call originating tone defined by ITU-T recommendation V.8.

COURIER HIGH SPEED MODEMS

J-4 Glossary

Carrier

A continuous frequency capable of being either modulated or

impressed with another information-carrying signal. Carriers

are generated and maintained by modems via the transmission

lines of the telephone companies.

CCITT

Formerly, an international organization that defined standards

for telegraphic and telephone equipment. It has been

incorporated into its parent organization, International

Telecommunication Union (ITU). Telecommunication

standards are now covered under Telecommunications

Standards Sector (TSS). ITU-T replaces CCITT. For example,

the Bell 212A standard for 1200 bps communication in North

America was referred to as CCITT V.22. It is now referred to as

ITU-T V.22.

Character

A representation, coded in binary digits, of a letter, number, or

other symbol.

Characters Per Second

A data transfer rate generally estimated from the bit rate and

the character length.

For example, at 2400 bps, 8-bit characters with Start and Stop

bits (for a total of ten bits per character) will be transmitted at a

rate of approximately 240 characters per second (cps). Some

protocols, such as USR-HST and MNP, employ advanced tech-

niques such as longer transmission frames and data com-

pression to increase cps.

Class 1/EIA-578

An American standard used between facsimile application

programs and facsimile modems for sending and receiving

Class 1 faxes.

Class 2.0/EIA-592

An American standard used between facsimile application

programs and facsimile modems for sending and receiving

Class 2.0 faxes.

COURIER HIGH SPEED MODEMS

Glossary J-5

Cyclic Redundancy Checking (CRC)

An error-detection technique consisting of a cyclic algorithm

performed on each block or frame of data by both sending and

receiving modems. The sending modem inserts the results of its

computation in each data block in the form of a CRC code. The

receiving modem compares its results with the received CRC

code and responds with either a positive or negative acknowl-

edgment. In the ARQ protocol implemented in U.S. Robotics

high speed modems, the receiving modem accepts no more data

until a defective block is received correctly.

Data Communications

A type of communications in which computers and terminals

are able to exchange data over an electronic medium.

Data Compression

When the transmitting modem detects redundant units of data,

it recodes them into shorter units of fewer bits. The receiving

modem then decompresses the redundant data units before

passing them to the receiving computer.

Data Compression Table

A table of values assigned for each character during a call under

data compression. Default values in the table are continually

altered and built during each call: the longer the table, the more

efficient throughput gained.

If a destructive Break is sent during a call (see the &Y com-

mand), causing the modems to reset the compression tables,

you can expect diminished throughput.

Data Mode

The mode in which the fax modem is capable of sending and

receiving data files. A standard modem without fax capabilities

is always in Data mode.

DCE

Data Communication (or Circuit-Terminating) Equipment. In

this manual, the term applies to dial-up modems that establish

and control the data link via the telephone network.

COURIER HIGH SPEED MODEMS

J-6 Glossary

Dedicated Line

A user-installed telephone line used to connect a specified num-

ber of computers or terminals within a limited area, for

example, one building. The line is a cable rather than a public-

access telephone line. The communications channel may also be

referred to as nonswitched because calls do not go through

telephone company switching equipment.

Default

Any setting assumed, at startup or reset, by the computer's soft-

ware and attached devices, and operational until changed by

the user.

Digital Loopback

A test that checks the modem's RS-232 interface and the cable

that connects the terminal or computer and the modem. The

modem receives data (in the form of digital signals) from the

computer or terminal, and immediately returns the data to the

screen for verification.

Digital Signals

Discrete, uniform signals. In this manual, the term refers to the

binary digits 0 and 1.

Duplex

Indicates a communications channel capable of carrying signals

in both directions. See Half Duplex, Full Duplex.

EIA

Electronic Industries Association, which defines electronic stan-

dards in the U.S.

Equalization

A compensation circuit designed into modems to counteract

certain distortions introduced by the telephone channel. Two

types are used: fixed (compromise) equalizers and those that

adapt to channel conditions. U.S. Robotics high speed modems

use adaptive equalization.

COURIER HIGH SPEED MODEMS

Glossary J-7

Error Control

Various techniques which check the reliability of characters

(parity) or blocks of data. V.42, MNP and HST error control

protocols use error detection (CRC) and retransmission of

errored frames (ARQ).

Facsimile

A method for transmitting the image on a printed page from

one point to another. Commonly referred to as Fax.

Fax Mode

The mode in which the fax modem is capable of sending and

receiving files in a facsimile format.

Flash ROM

Read Only Memory that can be erased and reprogrammed.

Flow Control

A mechanism that compensates for differences in the flow of

data input to and output from a modem or other device.

Frame

A data communications term for a block of data with header

and trailer information attached. The added information usu-

ally includes a frame number, block size data, error-check

codes, and Start/End indicators.

Full Duplex

Signal flow in both directions at the same time. In micro-

computer communications, may refer to the suppression of the

online Local Echo.

Half Duplex

Signal flow in both directions, but only one way at a time. In

microcomputer communications, may refer to activation of the

online Local Echo, which causes the modem to send a copy of

the transmitted data to the screen of the sending computer.

COURIER HIGH SPEED MODEMS

J-8 Glossary

HDLC

High Level Data Link Control. A standard protocol developed

by the International Standards Organization for software appli-

cations and communicating devices operating in synchronous

environments. The protocol defines operations at the link level

of communications, for example, the format of data frames

exchanged between modems over a phone line. See Bisync,

Protocol, SDLC.

HST

High Speed Technology, U.S. Robotics' proprietary signaling

scheme, design and error control protocol for high-speed

modems. HST incorporates trellis-coded modulation, for

greater immunity from variable phone line conditions, and

asymmetrical modulation for more efficient use of the phone

channel at speeds of 4800 bps and above. HST also incorporates

MNP-compatible error control procedures adapted to

asymmetrical modulation.

Hertz, a frequency measurement unit used internationally to

indicate one cycle per second.

ITU-T

International Telecommunication Union-Telecommunication

sector. Formerly referred to as CCITT. An international

organization that defines standards for telegraphic and

telephone equipment. For example, the Bell 212A standard for

1200 bps communication in North America is observed

internationally as ITU-T V.22. For 2400 bps communication,

most U.S. manufacturers observe V.22 bis.

LAPM

Link Access Procedure for Modems, an error control protocol

incorporated in ITU-T Recommendation V.42. Like the MNP

and HST protocols, LAPM uses cyclic redundancy checking

(CRC) and retransmission of corrupted data (ARQ) to ensure

data reliability.

COURIER HIGH SPEED MODEMS

Glossary J-9

Local Echo

A modem feature that enables the modem to send copies of key-

board commands and transmitted data to the screen. When the

modem is in Command mode (not online to another system) the

local echo is invoked through the ATE1 command. The com-

mand causes the modem to display your typed commands.

When the modem is online to another system, the local echo is

invoked through the ATF0 command. This command causes

the modem to display the data it transmits to the remote

system.

MI/MIC

Mode Indicate/Mode Indicate Common, also called Forced or

Manual Originate. Provided for installations where other

equipment, rather than the modem, does the dialing. In such

installations, the modem operates in Dumb mode (no Auto Dial

capability), yet must go off hook in Originate mode to connect

with answering modems. See MI/MIC Closure in Appendix G.

MNP

Microcom Networking Protocol, an asynchronous error control

protocol developed by Microcom, Inc. and now in the public

domain. The protocol ensures error-free transmission through

error detection (CRC) and retransmission of errored frames.

U.S. Robotics modems use MNP Levels 1−4 and Level 5 data

compression. MNP Levels 1−4 have been incorporated into

ITU-T Recommendation V.42. Compare HST.

Modem

A device that transmits/receives computer data through a com-

munications channel such as radio or telephone lines. The

Courier is a telephone channel modem that modulates, or trans-

forms, digital signals from a computer into the analog form

that can be carried successfully on a phone line. It also

demodulates signals received from the phone line back to

digital signals before passing them to the receiving computer.

COURIER HIGH SPEED MODEMS

J-10 Glossary

Nonvolatile Memory (NVRAM)

User-programmable random access memory whose data is

retained when modem power is turned off. Used in Courier

modems to store a user-defined default configuration loaded

into random access memory (RAM) at power on.

OFF/ON Hook

Modem operations which are the equivalent of manually lifting

a phone receiver (taking it off hook) and replacing it (going on

hook).

Online Fallback

A feature that allows high speed error-control modems to mon-

itor line quality and fall back to the next lower speed if line

quality degrades. The modems fall forward as line quality

improves.

Originate Mode

A state in which the modem transmits at the predefined low fre-

quency of the communications channel and receives at the high

frequency. The transmit/receive frequencies are the reverse of

the called modem which is in Answer mode.

Parallel Transmission

The transfer of data characters using parallel electrical paths for

each bit of the character, for example, 8 paths for 8-bit

characters. Data is stored in computers in parallel form, but

may be converted to serial form for certain operations. See

Serial Transmission.

Parity

An error-detection method that checks the validity of a trans-

mitted character. Character checking has been surpassed by

more reliable and efficient forms of block-checking, including

Xmodem-type protocols and the ARQ protocol implemented in

Courier modems.

The same type of parity must be used by two communicating

computers, or both may omit parity. When parity is used, a

parity bit is added to each transmitted character. The bit's value

is 0 or 1, to make the total number of 1's in the character even or

odd, depending on which type of parity is used.

COURIER HIGH SPEED MODEMS

Glossary J-11

Protocol

A system of rules and procedures governing communications

between two or more devices. Protocols vary, but communi-

cating devices must follow the same protocol in order to

exchange data. The format of the data, readiness to receive or

send, error detection and error correction are some of the opera-

tions that may be defined in protocols.

RAM

Random Access Memory. Memory that is available for use

when the modem is turned on, but that clears of all information

when the power is turned off. The modem's RAM holds the

current operational settings, a flow control buffer, and a

command buffer.

Remote Access

A feature that allows a remotely-located user to view the

Courier's configuration screens and change the Courier's

configuration. Password protection is available.

Remote Digital Loopback

A test that checks the phone link and a remote modem's trans-

mitter and receiver. Data entered from the keyboard is trans-

mitted from the initiating modem, received by the remote

modem's receiver, looped through its transmitter, and returned

to the local screen for verification.

Remote Echo

A copy of the data received by the remote system, returned to

the sending system and displayed on the screen. Remote echo-

ing is a function of the remote system.

ROM

Read Only Memory. Permanent memory, not user-pro-

grammable. The Courier's factory settings are stored in ROM

and can be read (loaded) into RAM as an operational configura-

tion if DIP switch S10 is ON at power on.

Serial Transmission

The transfer of data characters one bit at a time, sequentially,

using a single electrical path. See Parallel Transmission.

COURIER HIGH SPEED MODEMS

J-12 Glossary

Start/Stop Bits

The signaling bits attached to a character before the character is

transmitted during Asynchronous Transmission.

SDLC

Synchronous Data Link Control. A protocol developed by IBM

for software applications and communicating devices operating

in IBM's Systems Network Architecture (SNA). The protocol

defines operations at the link level of communications, for

example, the format of data frames exchanged between

modems over a phone line. See Bisync, Protocol, HDLC.

Synchronous Transmission

A form of transmission in which blocks of data are sent at

strictly timed intervals. Because the timing is uniform, no Start

or Stop bits are required. Compare Asynchronous

Transmission.

Some mainframes only support synchronous communications

unless their owners have installed a synchronous adapter and

appropriate software.

Terminal

A device whose keyboard and display are used for sending and

receiving data over a communications link. Differs from a

microcomputer in that it has no internal processing capabilities.

Used to enter data into or retrieve processed data from a system

or network.

Terminal Mode

An operational mode required for microcomputers to transmit

data. In Terminal mode the computer acts as if it were a stan-

dard terminal such as a teletypewriter, rather than a data

processor. Keyboard entries go directly to the modem, whether

the entry is a modem command or data to be transmitted over

the phone lines. Received data is output directly to the screen.

The more popular communications software products control

Terminal mode as well as enable more complex operations,

including file transmission and saving received files.

COURIER HIGH SPEED MODEMS

Glossary J-13

Throughput

The amount of actual user data transmitted per second without

the overhead of protocol information such as Start and Stop bits

or frame headers and trailers. Compare characters per second.

Transmission Rate

Same as Bit Rate.

V.17

An ITU-T standard for facsimile operations that specifies

modulation at 14.4K bps, with fallback to 12K bps.

V.21Fax

An ITU-T standard for facsimile operations at 300 bps. U.S.

Robotics or compatible fax devices then transmit or receive at

higher speeds.

V.21Modem

An ITU-T standard for modem communications at 300 bps.

Modems made in the U.S. or Canada follow the Bell 103 stan-

dard. However, the modem can be set to answer V.21 calls

from overseas.

V.22

A ITU-T standard for modem communications at 1200 bps,

compatible with the Bell 212A standard observed in the U.S.

and Canada.

V.22 bis

An ITU-T standard for modem communications at 2400 bps.

The standard includes an automatic link negotiation fallback to

1200 bps and compatibility with Bell 212A/V.22 modems.

V.23

An ITU-T standard for modem communications at 1200 bps

with a 75 bps back channel. Used in the U.K.

COURIER HIGH SPEED MODEMS

J-14 Glossary

V.25

An ITU-T standard for modem communications. Among other

things, V.25 specifies an answer tone different from the Bell

answer tone. All U.S. Robotics modems can be set with the B0

command so that they use the V.25 2100 Hz tone when answer-

ing overseas calls.

V.25 bis

An ITU-T standard for synchronous communications between

the mainframe or host and the modem using the HDLC or

character-oriented protocol. Modulation depends on the serial

port rate and setting of the transmitting clock source, &X.

V.27 ter

An ITU-T standard for facsimile operations that specifies

modulation at 4800 bps, with fallback to 2400 bps.

V.29

An ITU-T standard for facsimile operations that specifies

modulation at 9600 bps, with fallback to 7200 bps.

V.32

An ITU-T standard for modem communications at 9600 bps

and 4800 bps. V.32 modems fall back to 4800 bps when line

quality is impaired, and fall forward again to 9600 bps when

line quality improves.

V.32 bis

An ITU-T standard that extends the V.32 connection range:

4800, 7200, 9600, 12K and 14.4K bps. V.32 bis modems fall back

to the next lower speed when line quality is impaired, and fall

back further as necessary. They fall forward to the next higher

speed when line quality improves.

V.32 terbo

Modulation scheme that extends the V.32 connection range:

4800, 7200, 9600, 12K, 14.4K, 16.8K, 19.2K, and 21.6K bps. V.32

terbo modems fall back to the next lower speed when line

quality is impaired, and fall back further as necessary. They fall

forward to the next higher speed when line quality improves.

COURIER HIGH SPEED MODEMS

Glossary J-15

V.34

An ITU-T standard that allows data rates as high as 28.8K bps.

V.42

An ITU-T standard for modem communications that defines a

two-stage process of detection and negotiation for LAPM error

control.

V.42 bis

An extension of ITU-T V.42 that defines a specific data com-

pression scheme for use with V.42 error control. V.42 bis is only

supported with LAPM and HST.

V.8

ITU-T recommendation that defines procedures for starting and

ending sessions of data transmission.

V.Fast Class (V.FC)

Proprietary modulation scheme developed by Rockwell

International for data communication speeds up to 28.8K bps.

Word Length

The number of bits in a data character without parity, start or

stop bits.

Xmodem

The first of a family of error control software protocols used to

transfer files between modems. These protocols are in the

public domain and are available from many bulletin board

services.

XON/XOFF

Standard ASCII control characters used to tell an intelligent

device to stop/resume transmitting data. In most systems

typing <Ctrl>-S sends the XOFF character. Some devices,

including the Courier, understand <Ctrl>-Q as XON; others

interpret the pressing of any key after <Ctrl>-S as XON.

COURIER HIGH SPEED MODEMS

Technical Specifications K-1

APPENDIX K. TECHNICAL SPECIFICATIONS

Your modem uses multiple standard modulation protocols and

is also compatible with many nonstandard schemes.

V.34

28.8K, 26.4K, 24K, 21.6K, 19.2K, 16.8K, 14.4K, 12K, 9600, 7200,

4800, and 2400 bps asynchronous Trellis Coded Modulation

(TCM)

V.Fast Class (V.FC)

28.8K, 26.4K, 24K, 21.6K, 19.2K, 16.8K, 14.4K bps asynchronous

Trellis Coded Modulation (TCM)

U.S. Robotics V.32 terbo

21.6K, 19.2K, 16.8K, 14.4K. 12K, 9600, 7200 bps asynchronous,

19.2K, 16.8K, 14.4K. 12K, 9600, 7200 bps synchronous, Trellis

Coded Modulation (TCM)

4800 bps, synchronous/asynchronous, Quadrature Amplitude

Modulation (QAM)

U.S. Robotics High Speed Technology (HST)

16.8K, 14.4K, 12K, 9600, 7200 bps, synchronous/asynchronous,

asymmetrical, 450 bps back channel with automatic handshake

adjustment to 300 bps, Trellis Coded Modulation (TCM),

Quadrature Amplitude Modulation (QAM)

4800 bps, synchronous/asynchronous, asymmetrical, 450 bps

back channel with automatic handshake adjustment to 300 bps,

Quadrature Amplitude Modulation (QAM)

ITU-T V.32 bis

14.4K. 12K, 9600, 7200 bps, synchronous/asynchronous, Trellis

Coded Modulation (TCM)

4800 bps, synchronous/asynchronous, Quadrature Amplitude

Modulation (QAM)

COURIER HIGH SPEED MODEMS

K-2 Technical Specifications

Additional Compatibility Features

ITU-T V.32, 9600 bps, synchronous, asynchronous, Trellis

Coded Modulation (TCM); 4800 bps, synchronous,

asynchronous, Quadrature Amplitude Modulation (QAM)

ITU-T V.25 2100 Hz tone

ITU-T V.23, 1200 bps, asymmetrical (1200/75 bps), Frequency

Shift Keying (FSK)

ITU-T V.22 bis, 2400 bps, synchronous/asynchronous,

Quadrature Amplitude Modulation (QAM)

ITU-T V.22, 1200 bps, synchronous/asynchronous, Differential

Phase Shift Keying (DPSK)

Bell 212A, 1200 bps, synchronous/asynchronous, Differential

Phase Shift Keying (DPSK)

Bell 103, 300 bps, asynchronous, Frequency Shift Keying (FSK)

ITU-T V.21, 300 bps, asynchronous, Frequency Shift Keying

(FSK)

Error Control Standards

ITU-T V.42 error control protocol at 14.4K, 12K, 9600, 7200, 4800

bps (V.32 bis mode) and at 2400/1200 bps

U.S. Robotics HST error control protocol, asymmetrical mode,

at 16.8K, 14.4K, 12K, 9600, 7200, 4800 bps, 450/300 bps back

channel

Microcom Networking Protocol (MNP) error control protocol,

Levels 2-4 at 14.4K, 12K, 9600, 7200, 4800 bps (V.32 bis mode)

and at 2400/1200 bps

Data Compression Protocols

ITU-T V.42 bis data compression (all modes and speeds of 1200

bps and higher)

Microcom Networking Protocol (MNP) Level 5 data

compression (all modes and speeds of 1200 bps and higher)

COURIER HIGH SPEED MODEMS

Technical Specifications K-3

Fax Standards

The Courier modem provides Group III-compatibility when

combined with Class 1 or Class 2.0 fax software. In addition,

the modem adheres to the following standards.

TIA/EIA-578 Service Class 1 Asynchronous Facsimile

DCE Control Standard

TIA/EIA-592 Service Class 2.0 Asynchronous Facsimile

DCE Control Standard

ITU-T V.17 14.4K/12K bps

ITU-T V.29 9600/7200 bps

ITU-T V.27 ter 4800/2400 bps

ITU-T V.21 300 bps

SERIAL PORT RATES

115.2K, 57.6K, 38.4K, 19.2K, 9600, 4800, 2400, 1200, 300 bps

ADAPTIVE SPEED LEVELING

21.6K, 19.2K, 16.8K, 14.4K, 12K, 9600, 7200, 4800 bps

PHONE LINE INTERFACE

RJ11, RJ45S phone jacks

COMMUNICATIONS CHANNEL

Full/half duplex on 2-wire dial-up, dedicated, or leased phone

lines; demand-driven high speed channel turnaround in HST

mode; symmetrical speeds in V.32 bis mode

OPERATIONAL MODES

Synchronous/Asynchronous, Auto Dial/Answer, Manual

Originate/Answer, Smart/Dumb mode, Auto Dial/Auto

Answer, Auto Answer only, Forced Originate (MI/MIC)

Fax Modems: The above modes plus fax mode

DIALING

Dialing Rotary (pulse 0-9), Tone (DTMF 0-9, #, *), a-z when in

Quote (") Mode

COURIER HIGH SPEED MODEMS

K-4 Technical Specifications

DATA FORMAT

Binary, serial; defaults to 8-bit word length, no parity, and 1

stop bit

Word Parity Stop

Length (1 Bit) Bits

7Even, Odd 1

Mark, Space

7None 2

8None 1

FRONT PANEL STATUS LIGHTS

HS High Speed (above 2400 bps)

AA Auto Answer/Answer

CD Carrier Detect

OH Off Hook

RD Received Data

SD Send Data

TR Terminal Ready (DTR)

MR Modem Ready/Test mode

RS Request to Send

CS Clear to Send

SYN Synchronous mode

ARQ/Error control connection established

FAX Modem in Fax mode

FLOW CONTROL BUFFERS

Transmit Buffer

Error control: 3.25k bytes

Non-Error control: 1.5k bytes, 128-byte option

Receive Buffer: 2K bytes

COMMAND BUFFER

60 characters, exclusive of AT prefix, Carriage Return and

spaces

COURIER HIGH SPEED MODEMS

Technical Specifications K-5

TEST OPTIONS

Analog loopback with test pattern

Remote digital loopback

Digital loopback

Test pattern

Dial test

CALL PROGRESS CODES

FAX

DATA

NO DIAL TONE

BUSY

NO ANSWER

RINGING

VOICE

FAILED CALL TIMEOUT

60-sec. default, programmable 2-255 sec.

ANSWER TONE TIMEOUT

60 sec.

FAX SERVICE CLASS 1 COMMANDS

+FCLASS=n (0,1) Class identification and control

+FTS=n (0,255) Stop transmission and pause, 10ms.

+FRS=n (0,255) Wait for silence, 10 ms.

+FTM=n (3,24,48,72,73,74,96,121,122,145,146)

Transmit data with carrier

+FRM=n (3,24,48,72,73,74,96,121,122,145,146)

Receive data with carrier

+FTH=n (3,24,48,72,73,74,96,121,122,145,146)

Transmit HDLC data with carrier

+FRH=n (3,24,48,72,73,74,96,121,122,145,146)

Receive HDLC data with carrier

COURIER HIGH SPEED MODEMS

K-6 Technical Specifications

FAX SERVICE CLASS 2.0 COMMANDS

Class 2.0 fax commands are too numerous to be listed here. For

information on Class 2.0 technical specifications, contact Global

Engineering Documents, at 1-800-854-7179. The document that

covers this information is:

ANSI/EIA/TIA-592-1993 (EIA-592)

Asynchronous Facsimile DCE Control Standard

May, 1993

Optional Class 2.0 FAX commands supported

U.S. Robotics implements the following optional Class 2.0 fax

commands :

+FNS=0,1 Pass-through non-Standard negotiation

byte string

+FCR=0,1 Capability to receive

+FAA=0,1 Adaptive Answer mode

+FCT=0-255 sec. Phase C Timeout

+FHS=0-255 Hangup Status Code, read only

+FMS=0-3 Minimum Phase C Speed

+FBS?=500,100 Buffer size, read only

V.25 BIS SYNCHRONOUS COMMANDS AND RESULT CODES

Commands: Connect incoming call (CIC); Call request using

number provided (CRN); Call Request with memory location

(CRS); Disregard incoming call (DIC); Program number (PRNn);

Request list of forbidden numbers (RFN); Request list of stored

numbers (RLN).

Dial options: 0−9 & : > < = P T);

Result Codes: Call failure indication (CFI) with optional

parameters: Abort call (CFAB); local modem busy (CFCB);

Engaged tone (CFET); Forbidden call (CFFC); Number not

stored (CFNS); Answer tone not detected (CFNT); Ring tone

(CFRT); Connect (CNX); List of numbers (LS); List of forbidden

numbers (LSF); List of stored numbers (LSN); Incoming call

(INC); Invalid (INV) with optional parameters: Message syntax

error (INVMS); Command Unknown (INVCU); Parameter

syntax error (INVPS); Parameter value error (INVPV); Valid

(VAL).

COURIER HIGH SPEED MODEMS

Technical Specifications K-7

Commands and Result Codes not supported: Call request

with identification number (CRI); Program identifier (PRI);

Request list of identification numbers (RLI); List of delayed call

numbers (RLD).

ANSWER TONE DETECTOR

2200-2300 Hz

LOSS OF CARRIER (DISCONNECT TIMER)

0.7-sec. default, programmable 0.2-25.5 sec.

EQUALIZATION

Adaptive

TRANSMITTER CARRIER FREQUENCIES

V.34

Originate Mode: 1800 Hz

Answer Mode: 1800 Hz

Originate Mode: 1829 Hz

Answer Mode: 1829 Hz

Originate Mode: 1867 Hz

Answer Mode: 1867 Hz

Originate Mode: 1920 Hz

Answer Mode: 1920 Hz

Originate Mode: 1959 Hz

Answer Mode: 1959 Hz

Originate Mode: 2000 Hz

Answer Mode: 2000 Hz

V.Fast Class

Originate Mode: 1800 Hz

Answer Mode: 1800 Hz

COURIER HIGH SPEED MODEMS

K-8 Technical Specifications

Originate Mode: 1875 Hz

Answer Mode: 1875 Hz

Originate Mode: 1920 Hz

Answer Mode: 1920 Hz

USR-V.32 terbo/V.32 bis/V.32

Originate Mode: 1800 Hz

Answer Mode: 1800 Hz

USR-HST, 450 bps back channel

Originate Mode: 375 Hz

Answer Mode: 1800 Hz

USR-HST, 300 bps back channel

Originate Mode: 350 Hz

Answer Mode: 1800 Hz

V.23

Originate Mode:

Mark: 390 Hz

Space: 450 Hz

Answer Mode:

Mark: 1300 Hz

Space: 2100 Hz

V.22 bis, V.22, Bell 212A

Originate Mode: 1200 Hz

Answer Mode: 2400 Hz

Bell 103

Originate Mode:

Mark: 1270 Hz

Space: 1070 Hz

Answer Mode:

Mark: 2225 Hz

Space: 2025 Hz

COURIER HIGH SPEED MODEMS

Technical Specifications K-9

V.21

Originate Mode:

Mark: 980 Hz

Space: 1180 Hz

Answer Mode:

Mark: 1650 Hz

Space: 1850 Hz

RECEIVER CARRIER FREQUENCIES

V.34

Originate Mode: 1800 Hz

Answer Mode: 1800 Hz

Originate Mode: 1829 Hz

Answer Mode: 1829 Hz

Originate Mode: 1867 Hz

Answer Mode: 1867 Hz

Originate Mode: 1920 Hz

Answer Mode: 1920 Hz

Originate Mode: 1959 Hz

Answer Mode: 1959 Hz

Originate Mode: 2000 Hz

Answer Mode: 2000 Hz

V.Fast Class

Originate Mode: 1800 Hz

Answer Mode: 1800 Hz

Originate Mode: 1875 Hz

Answer Mode: 1875 Hz

Originate Mode: 1920 Hz

Answer Mode: 1920 Hz

COURIER HIGH SPEED MODEMS

K-10 Technical Specifications

USR-V.32 terbo/V.32 bis/V.32

Originate Mode: 1800 Hz

Answer Mode: 1800 Hz

USR-V.32 terbo/V.32 bis/V.32

Originate Mode: 1800 Hz

Answer Mode: 1800 Hz

USR-HST, 450 bps back channel

Originate Mode: 1800 Hz

Answer Mode: 375 Hz

USR-HST, 300 bps back channel

Originate Mode: 1800 Hz

Answer Mode: 350 Hz

V.23

Originate Mode:

Mark: 1300 Hz

Space: 2100 Hz

Answer Mode:

Mark: 390 Hz

Space: 450 Hz

V.22 bis, V.22, Bell 212A

Originate Mode: 2400 Hz

Answer Mode: 1200 Hz

Bell 103

Originate Mode:

Mark: 2225 Hz

Space: 2025 Hz

Answer Mode:

Mark: 1270 Hz

Space: 1070 Hz

COURIER HIGH SPEED MODEMS

Technical Specifications K-11

V.21

Originate Mode:

Mark: 1650 Hz

Space: 1850 Hz

Answer Mode:

Mark: 980 Hz

Space: 1180 Hz

RECEIVE SENSITIVITY

- 44 dBm + 2 dBm

TRANSMIT LEVEL

- 9 dBm maximum

TRANSMITTER FREQUENCY TOLERANCE

.01%

CERTIFICATION

FCC Part 68 and Part 15, Class B Domestic; IC (Canada), UL

listed

POWER CONSUMPTION

5 watts

SIZE

6.375 x 10.3 x 1.337 inches

COURIER HIGH SPEED MODEMS

Index 1

INDEX

Command List Bold entries indicate primary references.

+++, return to Command mode, 4-10, C-2

+FAA, Call Detection, 5-4

+FCLASS=n, Fax/Data mode, 5-2

+FCLASS?, display mode, 5-2

>, repeat, 4-7, C-3

/, pause, 4-5, C-5

$, basic command help, 6-8–6-11

&$, ampersand command help, 6-9

&A, enable ARQ result codes, 4-17–4-18, C-9

&B, computer or terminal/modem rate,

4-21–4-22, C-9

&C, Carrier Detect, 4-23, C-9

&D, Data Terminal Ready, 4-23–4-24, C-10

&F, load factory configurations, 4-11–4-12, C-10,

B-9–B-13

&G, Guard tone, 4-30, C-11

&H, Transmit Data flow control, 4-26–4-27,

C-11

&I, Received Data software flow control,

4-27–4-29, C-11–C-12

&K, Data compression, 4-20, C-12

&L, leased line operation, F-15

&M, error control, 4-19–4-20, C-12–C-13, F-6–F-7

&N, connection link rate, 4-22–4-23, C-13–C-14,

F-5, F-11–F-12

&P, make/break ratio, 4-31, C-14

&R, Received Data hardware flow control,

4-27, C-14

&S, Data Set Ready, 4-24, C-14–C-15

&T, test options, C-15, Appendix H

&W, write to NVRAM, 4-12, C-15

&X, synchronous timing source, F-3

&Y, break handling, 4-31, C-16

&Zn=s, write number to NVRAM, 4-7, C-17

&Zn?, display number in NVRAM, 4-7, 6-7,

C-17

&ZC=s, store command string, 4-32, C-16–C-17

&ZC?, display stored command string, 4-32, C-

%$, percent command help, 6-11

%A, Dial Security accounts, C-18, D-4–D-5

%B, remote access, C-18, D-14

%C, remote access configuration control,

C-18, D-14–D-15

%E, erase Dial Security parameter(s), C-18–C-19,

D-8

%F, configure data format, C-19, D-15

%L, local security password, C-19, D-5

%N, synchronous DTE rate, C-19, F-4–F-5

%Pn=s, password security, C-19, D-10–D-11,

D-15

%Pn?, display password, C-19, D-15

%S, Dial Security status, C-19, D-7

%T, Tone recognition, 4-32, C-20

%V, autopass password, C-20, D-9

A, force answer mode, 4-8, C-3

A/, repeat last command, 4-7, C-3

A>, continuous repeat, 4-8, C-3

Any key, terminate current operation, 4-3, C-3

AT, attention command prefix, 4-1, 4-3, C-1,

C-3

B, handshake options, 4-19, C-4

C, disable transmitter, 4-31, C-4

D, dial, 4-4–4-6, C-4

$, dial command help, 6-10

@, wait for an answer, 4-5, C-5

, (comma), pause, 4-4, C-4

/ (slash), short pause, 4-5, C-5

; (semi-colon), return to Command mode,

4-4, C-4

" (quotation mark), dial letters, 4-5, C-4

! (exclamation point), transfer call, 4-5, C-4

P, pulse dial, 4-4, C-4

R, reverse frequencies, 4-6, C-5

T, Tone dial, 4-4, C-4

W, wait for second dial tone, 4-5, C-4

DL, dial last-dialed number, 4-5, C-5

DL?, display last-dialed number, 6-8

DS, dial number stored in NVRAM, 4-6, C-5

E, Command mode local echo, 4-13, C-5

F, online local echo, 4-13–4-14, C-5

H, on/off hook control, 4-9, C-5

I, inquiry options, Chapter 6, C-6

K, modem clock, 4-31, C-6

L, speaker volume control, C-6

M, speaker control, 4-13, C-7

O, return online, 4-11, C-7

P, pulse dial, 4-4, C-4

Q, quiet mode, 4-14, C-7

S$, S-Register help, 6-10

Sr?, S-Register query, B-15, C-7

Sr=n, set S-Register value, B-15, C-7

T, tone dial, 4-4, C-4

V, verbal/numeric mode, 4-14, C-7

X, result code options, 4-15–4-16, C-8

Z, reset to NVRAM settings, 4-13, C-8

COURIER HIGH SPEED MODEMS

2 Index

AA, see LEDs

ACK character, HP installations, 2-4, 4-28,

G-8

Adapter,

Card (synchronous), F-10

Phone, See RJ11C

Power, 2-2

Adaptive dialing (Xn), 4-6, 4-15, 4-16

Adaptive Speed Leveling, 1-2, A-2–A-3

Advanced result code subsets (&A),

4-17–4-8

Ampersand (&) commands, C-9–C-17

Analog loopback (AL)

S16, B-20

&T, Chapter 6

Al, see Analog Loopback

ANSI, 5-3

Answer

automatic, see Auto Answering

commands, 4-4–4-11

“dumb” V.32 modems, A-3

force (A), 4-8, C-13

mode, 4-8–4-9

See DIP switch 5

Any key, 4-3, C-3

ARQ (Automatic Repeat Request)

CONNECT result codes (&A), 4-17–4-18

definition, 4-17, A-1

disconnect reason (I6), 6-6

during testing, Appendix H

enable (&M), 4-19–4-20, C-12–C-13

flow control requirement, 4-27, 4-28

mode select (&M, &D), 4-19, 4-25

operations, see Error Control

timeout, retransmit maximum, 4-7–4-8

ARQ/FAX, see LEDs

ASCII

changing definitions, see S-Registers

chart, B-29

ASL, see Adaptive Speed Leveling

Assembly,

External modem, Chapter 2

Internal modem, Chapter 3

Asterisk (*) dialing, 4-4, C-4

AT command, 4-1, C-1, C-3

Audio monitor (speaker), 4-14

Auto answering,

disabling, 4-8, 4-9

number of rings on which to answer (S0),

4-9, B-14

reverse (S13), B-18

see Voice/Data switch options

suppress (S0), B-14

with Dip switch 5, 4-8

Autobaud, 4-21

Auto dialing,

Help screen (D$), 6-10

S13), B-18

see Stored phone numbers

see Voice/Data switch options

Automatic Repeat Request, see ARQ

Autopass, Appendix D

Back channel,

forcing 300-bps (S15), B-19

Backspace key,

ASCII definition (S5), B-14

set to delete (S15), B-19

Basic commands, 4-3, 6-8

Baud rate, see Serial port rate and Bits per

Second

BBS, see Bulletin Board Service

Binary files, 4-20, 4-25, 4-29, A-5

BISYNC, 4-19

Bits per second (bps), J-3

Blers, 6-3

BPS, J-3

Bottom panel, 1-5

Break

handling (&Y), 4-31, C-16

length, modem to terminal (S21), B-14,

B-20

Buffers

command, 4-2, C-1

flow control, 4-25–4-26

NVRAM, C-16

Bulletin Board Service

USR, I-1

BUSY, 4-15, 4-16

Busy out, see Voice/Data switch options

Cable, see Phone Jacks, RS-232, and Shielded

Cabling, 2-5

Call duration reporting (K), 1-4, 4-31, C-16,

6-1

COURIER HIGH SPEED MODEMS

Index 3

Call progress messages, 1-4

Usrobotics V 34 Users Manual FRONT

V.34 to the manual c7c4e21b-5d51-4e33-a32a-084b603c9f54

Navigation menu

Versions of this User Manual:

Views

Navigation