Multi-Tech Systems MT2834MR6 User Manual

MultiModem

MT2834MR6

User Guide

MultiModem MT2834MR6 User Guide
PN: S000326A

Copyright ©2003 by Multi-Tech Systems, Inc.
All rights reserved. This publication may not be reproduced, in whole or in part, without prior written permission from Multi-

Tech Systems, Inc.
Multi-Tech Systems, Inc. makes no representations or warranties with respect to the contents hereof and specifically

disclaims any implied warranties of merchantability or fitness for any particular purpose. Furthermore, Multi-Tech
Systems, Inc. reserves the right to revise this publication and to make changes from time to time in the content hereof
without obligation of Multi-Tech Systems, Inc. to notify any person or organization of such revisions or changes.

Revision Date Description

A 12/30/2003 Initial release of MT2834MR6 User Manual on CD.

Trademarks

Trademarks of Multi-Tech Systems, Inc. are as follows: MultiExpress, MultiExpressFax, MultiModemII, Multi-Tech and the
Multi-Tech logo. Windows is a registered trademark of Microsoft Corporation.

Technical Support

France [e-mail] [phone]
India [e-mail] [phone]
U.K. [e-mail] [phone]
U.S., Canada [e-mail] [phone]
Rest of World [e-mail] [phone]

World Headquarters

Multi-Tech Systems, Inc.
2205 Woodale Drive
Mounds View, Minnesota 55112 U.S.A.
[phone] or [phone]
U.S. FAX [phone]
Technical Support [phone]
www.multitech.com

Contents

Chapter 1 - Introduction..................................................................................... 7

1.1 Introduction ............................................................................................. 8

1.2 Manual Organization...............................................................................8

1.3 Description ............................................................................................. 9

1.4 FCC Regulations for Telephone Line Interconnection........................... 10

1.4.1 FCC Fax Update ................................................................................. 10

1.5 Canadian Limitations Notice................................................................. 1 1

1.6 Technical Specifications ....................................................................... 12

1.7 Power Supply ....................................................................................... 14

1.8 Modem LED Indicators ......................................................................... 15

1.9 Busy Switch ......................................................................................... 15

1.10 MT2834MR6 Installation Notes ............................................................. 16

1.11 Safety Warnings ................................................................................... 16

Chapter 2 - Dialing and Answering ................................................................. 17

2.1 Introduction ........................................................................................... 18

2.2 Dial-Up Automatic Answering ............................................................... 18

2.3 Dial-Up Handshaking Details................................................................ 18

2.4 Call T ermination.................................................................................... 19

Chapter 3 - AT Commands .............................................................................. 20

3.1 Working with AT Commands................................................................ 21

3.1.1 Modes of Operation ............................................................................ 21

3.2.2 Command Structure............................................................................2 2

3.3.3 Command Editing ............................................................................... 22

3.2 Dialing Commands ............................................................................... 26

3.3 Dial Modifier Commands ...................................................................... 27

3.4 Phone Number Memory Commands.................................................... 30

3.5 Configuration Storage and Recall Commands..................................... 32

3.6 Modem Response (Result Code) Commands..................................... 34

3.7 Online Connection Commands ............................................................ 36

3.8 V.34 Commands................................................................................... 40

3.9 RS-232 Interface Commands .............................................................. 41

3.10 Error Correction and Data Compression Commands .......................... 43

3.11 Speed Conversion Commands ............................................................ 45

3.12 Immediate Action Commands .............................................................. 47

3.12 Flow Control Commands ..................................................................... 49

3.13 Escape Sequences.............................................................................. 52

3.14 Remote Configuration Commands ....................................................... 53

3.15 Line Probe Commands ........................................................................ 54

3.16 Diagnostic Commands ......................................................................... 55

Chapter 4 - S-Registers.................................................................................... 56

4.1 Introduction ........................................................................................... 57

4.2 S-Registers .......................................................................................... 57

4.3 Reading and Assigning S-Register Values ........................................... 63

4.3.1 Examples of Assigning Values ...........................................................63

4.3.2 Examples of Reading Values..............................................................63

4.4 AT Commands Affecting S-Registers................................................... 64

Chapter 5 - Error Correction, Data Compression & Speed Conversion..... 65

5.1 Introduction ........................................................................................... 66

5.2 How V.42 Detects and Corrects Errors ................................................ 67

5.3 Data Compression ............................................................................... 68

5.4 MNP Classes........................................................................................ 68

5.5 V.42 Mode Select Command (#L)......................................................... 69

5.5.1 #L0 Command..................................................................................... 69

5.5.1.1 Originate Mode ................................................................................69

5.5.1.2 Answer Mode...................................................................................6 9

5.5.2 #L1 Command..................................................................................... 69

5.5.3 #L2 Command ....................................................................................69

5.5.4 #L3 Command..................................................................................... 69

5.6 Modes of Operation .............................................................................. 70

5.6.1 Non-Error Correction Mode (&E0)........................................................70

5.6.2 Reliable Mode (&E2) ........................................................................... 70

5.6.3 Autoreliable Mode (&E1) .....................................................................70

5.7 Flow Control ......................................................................................... 71

5.8 Modem-Initiated Flow Control ............................................................... 72

5.8.1 XON/XOFF Flow Control (&E5)........................................................... 72

5.8.2 Hardware Flow Control (&E4) ..............................................................7 2

5.9 Pacing (&E13) ...................................................................................... 73

5.9.1 XON/XOFF Pass-Through (&E7) ........................................................ 73

5.9.2 Non-Error Correction Mode Flow Control (&E10 and &E11).................7 3

5.9.3 Hewlett Packard ENQ/ACK Pacing (&E9)...........................................7 3

5.10 Compression, Error Correction, Flow Control,

and Pacing Commands ........................................................................ 74

5.10.1 V.42 Error Correction Modes ..............................................................74

5.10.2 Modem-Initiated Flow Control ............................................................. 74

5.10.3 XON/XOFF Pass-Through ..................................................................74

5.10.4 Hewlett Packard ENQ/ACK Pacing.....................................................74

5.10.5 Non-Error Correction Mode Flow Control ............................................. 74

5.10.6 Pacing (Computer-Initiated Flow Control)............................................ 74

5.10.7 Data Compression ..............................................................................74

5.11 Result Codes ........................................................................................ 75

5.11.1 MNP Error Correction.......................................................................... 75

5.11.2 LAP-M Error Correction....................................................................... 75

5.11.3 Data Compression ..............................................................................75

5.12 Speed Conversion ................................................................................ 75

5.12.1 Baud Adjust ($BA) .............................................................................. 76

5.12.2 Modem Baud Rate ($MB)....................................................................76

5.12.3 Serial Port Baud Rate ($SB) ............................................................... 77

5.13 Related Commands ............................................................................. 78

5.13.1 Autoreliable Buffering ($A) ..................................................................78

5.13.2 Maximum Block Size (&BS) ...............................................................7 8

5.13.3 Autoreliable Fallback Character ($F) ................................................... 78

5.13.4 Retransmit Count ($R) ........................................................................ 79

5.13.5 V.42 Error Correction at 300 bps ($E) ................................................. 79

5.14 Summary.............................................................................................. 79

Chapter 6 - Testing & Troubleshooting.......................................................... 80

6.1 Introduction ........................................................................................... 81

6.2 Local Analog Loopback Test (V .54 Loop 3)........................................... 82

6.2.1 Test Procedure ...................................................................................82

6.3 Remote Digital Loopback Test (V.54 Loop 2)........................................ 83

6.3.1 Test Procedure ...................................................................................83

6.4 Local Digital Loopback Test (V.54 Loop 2)............................................ 84

6.4.1 Test Procedure ...................................................................................84

Chapter 7 - Warranty & Service....................................................................... 85

7.1 Multi-Tech Systems, Inc. Warranty & Repairs Policies......................... 86

7.1.1 Warranty ............................................................................................. 86

7.1.2 U.S. and Canadian Customers............................................................86

7.1.3 International Customers (outside U.S.A. and Canada)........................87

7.1.4 International Distributors.....................................................................8 7

7.2 Repairs................................................................................................. 88

7.2.1 Repair Procedures for U.S. and Canadian Customers ........................ 88

7.2.2 Repair Procedures for International Customers...................................88

7.2.3 Repair Procedures for International Distributors..................................89

7.2.4 Replacement Parts .............................................................................89

7.3 Technical Support ................................................................................. 89

7.4 Internet Site .......................................................................................... 89

Appendices........................................................................................................ 90

Appendix A..................................................................................................... 91

ASCII Conversion Chart...................................................................................91

Appendix B .................................................................................................... 92

Dial Pulses ...................................................................................................... 92

Tone Dial Frequencies ..................................................................................... 93

Appendix C .................................................................................................... 94

Result Code Summary..................................................................................... 94

Appendix D .................................................................................................... 96

S-Register Summary ....................................................................................... 96

Appendix E .................................................................................................... 98

AT Command Summary .................................................................................. 98

Appendix F................................................................................................... 106

RS-232C Interface Specifications..................................................................10 6

Functional Description of the RS-232C Signals ............................................. 10 7

Transmitted Data (TD) — Pin 2 ......................................................................10 7

Received Data (RD) — Pin 3.......................................................................... 10 7

Request To Send (RTS) — Pin 4.................................................................... 10 7

Clear To Send (CTS) — Pin 5......................................................................... 107

Data Set Ready (DSR) — Pin 6 ..................................................................... 107

Signal Ground (SG) — Pin 7 ..........................................................................10 7

Carrier Detect (CD) — Pin 8 ........................................................................... 107

Test Voltage (+V) — Pin 9 .............................................................................. 108

High Speed (HS) — Pin 12.............................................................................10 8

Transmit Clock (TC) — Pin 15........................................................................ 108

Receive Clock (RC) — Pin 17 ........................................................................ 108

Data Terminal Ready (DTR) — Pin 20 ............................................................10 8

Ring Indicator (RI) — Pin 22 .......................................................................... 10 9

External Transmit Clock (XTC) — Pin 24........................................................10 9

Terminal Busy (OOS) — Pin 25...................................................................... 10 9

Appendix G .................................................................................................. 110

Cable and Connector Diagrams ..................................................................... 110

APPENDIX H ................................................................................................111

Introduction to MultiTech Escape Methods ................................................... 111

How to Select an Escape Method..................................................................11 2

Escape Method 1: +++AT<CR> ..................................................................... 112

Escape Method 2: <BREAK>AT<CR> ........................................................... 112

S-Registers and Escape Sequence ...............................................................11 3

Aborting an Escape Sequence ...................................................................... 11 3

APPENDIX I................................................................................................. 1 14

Introduction to Remote Configuration............................................................. 114

Basic Procedure ............................................................................................ 1 14

Setup 11 4

Changing the Passwords ............................................................................... 11 5

Changing the Remote Escape Character ....................................................... 11 5

Index................................................................................................................. 116

Chapter 1 - Introduction

Chapter 1 - Introduction

1.1 Introduction

Welcome to the world of data communications. You have acquired one of the finest rack-mount intelligent
modems available, the MT2834MR6, from Multi-Tech Systems. This owner’s manual will help you install,
configure, test, and use your modem.

Your MT2834MR6 is designed to operate as an enhanced ITU-T V.34 dial-up modem. As such, it includes
the advanced features of Multi-Tech standalone modems, such as the popular MultiModemZDXb.

This manual documents all of the MT2834MR6’s features and capabilities, such as autodial, autoanswer,
auto-fallback, number linking, option switches, phone number memory, call progress detection, and more.
The next section will show you how to use this manual. The contents of each chapter are described, so you
will know where to turn for specific information.

1.2 Manual Organization

Chapter 1 Introduction and Description
This chapter describes the MT2834MR6 and its LED indicators, gives its technical specifications, and
provides a guide to the organization of the manual.

Chapter 2 Dialing and Answering
This chapter describes answer mode operation in detail, including handshaking procedures between two
modems and an autoanswer application. Various methods of call termination are also described.

Chapter 3 Command Mode Operation
This chapter provides an introduction to MT2834MR6 command mode fundamentals, followed by a detailed
explanation of each AT command, providing examples where applicable.

Chapter 4 S-Registers
This chapter describes the MT2834MR6’s S-registers, which are used to store various modem options. Each
S-register is defined and explained.

Chapter 5 Error Correction, Data Compression and Speed Conversion
This chapter provides detailed information about some of the advanced features of the MT2834MR6, namely,
V.42 error correction, data compression, speed conversion, and other features that improve throughput.

Chapter 6 Testing the MT2834MR6
This chapter describes loopback testing for the MT2834MR6.

Chapter 7- Warranty, Service, and Technical Support
This chapter provides the terms of the MT2834MR6’s warranty, instructions for obtaining factory service, and
information about Multi-Tech’s BBS and technical support. Information on upgrading the MT2834MR6’s
firmware is also provided.

Appendices
This chapter includes sections pertaining to ASCII/HEX/Decimal Conversion Chart, Dial Pulses and Tone
Dial Frequencies, Result Code Summary, S-Register Summary, AT Command Summary, RS-232 Interface
Specifications, Cable and Connector Diagrams, Escape Methods, and Remote Configuration.

8

Chapter 1 - Introduction

1.3 Description

Each MT2834MR6 card contains six integrated 33,600 bps MultiModems. Each modem on the MT2834MR6
card can be configured independently of the others via the MultiModemManager controller card (Model
MR4800 or MR4800E), which can support and control up to 16 MultiModem cards per rack. Refer to your
MultiModemManager

Perhaps the most significant extras incorporated in the MT2834MR6 are its V.42 error correction and V.42bis
data compression features. With error correction and data compression, transmission errors are eliminated
while increasing the modem’s throughput by a ratio of up to 4:1, for an effective overall transmission rate
approaching 115,200 bps.

The MT2834MR6 offers interactive automatic dialing capability, as well as command mode option
configuration. Two dial command strings, of up to 60 digits each, can be stored in each modem’s nonvolatile
memory. The modem supports both pulse and tone dialing, and can recognize dial tones and busy signals
for reliable call-progress detection.

The MT2834MR6 is registered by the FCC for direct connection to the public telephone networks. No Data
Access Arrangements (DAAs) are required.

The MT2834MR6 is fully compatible with the standard AT command set, and is therefore compatible with all
popular communications software packages.

Owner’s Manual

for more information about the rack and its components.

9

Chapter 1 - Introduction

1.4 FCC Regulations for Telephone Line Interconnection

1. No repairs are to be made by you. Repairs are to be made only by Multi-Tech Systems or its licensees.
Unauthorized repairs void registration and warranty. Contact Multi-Tech Systems, Inc. for details of how
to have repairs made.

2. When trouble is experienced, you must disconnect your modem from the telephone company’s jack to
determine the cause of the trouble, and reconnect your modem only when the trouble is corrected.

3. The modem cannot be connected to pay telephones or party lines.

4. If requested by the telephone company, you must notify them of the following before the MT2834MR6 is
installed:

a. The particular phone line (phone number) to which the connection is to be made.
b. The FCC Registration Number: AU7USA-30805-MM-E
c. The Ringer Equivalence: 0.3B
d. Modems can only be connected to the phone lines through standard modular jacks. The

Uniform Service Order Code (U.S.O.C.) for the standard modular jack which connect the modem
to the phone lines are: RJ-11C or RJ-11W (single line)

e. The manufacturer’s name and model number: Multi-Tech Systems - Model MT2834MR6

5. If the telephone company notifies you that your device is causing harm, unplug it. The telephone
company may disconnect your service if necessary and also may change its facilities, equipment,
operations or procedures which may affect operation of your equipment. Where practical, the telephone
company must promptly inform you in writing of the temporary disconnect or change in service, give you
the opportunity to make changes allowing uninterrupted service, and inform you of your rights to bring a
complaint to the FCC.

1.4.1 FCC Fax Update

The Telephone Consumer Protection Act of 1991 makes it unlawful for any person to use a computer or other
electronic device to send any message via a telephone fax machine unless such message clearly contains in
a margin at the top or bottom of each page or the first page of the transmission, the date and time it is sent
and an identification of the business or other entity, or other individual sending the message and the
telephone number of the sending machine or such business, other entity, or individual.

See your fax software manual for setup details.

10

Chapter 1 - Introduction

1.5 Canadian Limitations Notice

Notice: The ringer equivalence number (REN) assigned to each terminal device provides an indication of the

maximum number of terminals allowed to be connected to a telephone interface. The termination of a
interface may consist of any combination of devices subject only to the requirement that the sum of the ringer
equivalence numbers of all the devices does not exceed 5.

Notice: The Industry Canada label identifies certificated equipment. This certification means that the
equipment meets certain telecommunications network protective, operational and safety requirements.
Industry Canada does not guarantee the equipment will operate to the user’s satisfaction.

Before installing this equipment, users should ensure that it is permissible to be connected to the facilities of
the local telecommunications company. The equipment must also be installed using an acceptable method of
connection. The customer should be aware that compliance with the above conditions may not prevent
degradation of service in some situations.

Repairs to certified equipment should be made by an authorized Canadian maintenance facility designated
by the supplier. Any repairs or alterations made by the user to this equipment, or equipment malfunctions,
may give the telecommunications company cause to request the user to disconnect the equipment.

Users should ensure for their own protection 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.

Caution: Users should not attempt to make such connections themselves, but should contact the appropriate
electric inspection authority, or electrician, as appropriate.

Industry Canada Certification Number:
Ringer Equivalence Number (REN): 0.2

11

Chapter 1 - Introduction

1.6 Technical Specifications

Model Number MT2834MR6
Data Rates (Modem) Six independent modems (Modem A, B, C, D, E, F), each operating at 33,600,

31,200, 28,800, 26,400, 24,000, 21,600, 19,200, 16,800, 14,400, 12,000, 9600,
4800, 2400, 1200, or 0-300 bps

Data Rates (Fax) 14,400, 9600, 4800, and 2400 bps
Data Format (Modem) Serial, binary, asynchronous at all data rates
Configuration Each of the card’s six modems is independently configurable
Compatibility (Modem) ITU-T V.42bis, V.42, V.34, AT&T V.32terbo, ITU-T V.32bis, V.32, V.25bis, V.21,

V.22bis, V.22, V.23, V.17, Bell 212A* and 103/113*

Compatibility (Fax) ITU-T Group 3, T.4, T.30, V.21, V.27ter, V.29, V.17, and EIA TR29.2
Error Correction ITU-T V.42 (MNP® Classes 3 and 4, and LAP-M)
Data Compression ITU-T V.42bis (4:1 throughput) or MNP 5 (2:1 throughput)
Speed Conversion Serial port data rates adjustable to 300, 1200, 2400, 4800,9600, 19,200, 38,400,

57,600, and 115,200 bps

Flow Control XON/XOFF, CTS/RTS, ENQ/ACK
Mode of Operation Half or full duplex over dial-up lines; automatic or manual dialing, automatic or

manual answer

Intelligent Features Fully AT command compatible; autodial; redial; repeat dial*; dial linking*; pulse or

tone dial; dial pauses; call status display; auto-parity and data rate selection;
keyboard-controlled modem options; nonvolatile memory; on-screen displays of
modem parameters, stored telephone numbers, and help menus; and remote
configuration.

AT Commands 100% compatible with standard AT command set
Command Buffer 60 characters
Automatic Dialing Standard AT command asynchronous dialing
Modem Modulations FSK at 300 bps, PSK at 1200 bps, QAM at 2400, 4800, and 9600 bps (non-trellis),

QAM with trellis-coded modulation (TCM) at 9600, 12,000, 14,400, 16,800, 19,200,
21,600, 24,000, 26,400, 28,800, 31,200, and 33,600 bps

Fax Modulations V.21 CH2 FSK at 300 bps

V.27ter DPSK at 4800 and 2400 bps
V.29 QAM at 9600 and 7200 bps
V.17TCM at 14400, 12000, 9600, and 7200 bps

Carrier Frequencies 1600, 1646, 1680, 1800, 1829, 1867, 1920,
ITU-T V.34 1959, 2000 Hz
Carrier Frequencies: 1800 Hz
AT&T V.32 terbo/
ITU-T V.32bis/V.32
Carrier Frequencies: Transmit originate: 1200 Hz
V.22bis/V.22 or Transmit answer: 2400 Hz
Bell 212A Standard Receive originate: 2400 Hz
(2400 & 1200 bps) Receive answer: 1200 Hz

12

Carrier Frequencies: Transmit originate: 1270 Hz mark
Bell 103/113 1070 Hz space
(300 bps) Receive originate: 2225 Hz mark

2025 Hz space

Transmit answer: 2225 Hz mark

2025 Hz space

Receive answer: 1270 Hz mark

1070 Hz space

Carrier Frequencies: Transmit originate: 980 Hz mark
V.21 1180 Hz space

Receive originate: 1650 Hz mark

1850 Hz space

Transmit answer: 1650 Hz mark

1850 Hz space

Receive answer: 980 Hz mark

1180 Hz space

Carrier Frequencies: Transmit originate: 390 Hz mark
V.23 450 Hz space

Receive originate: 1300 Hz mark

2100 Hz space

Transmit answer: 1300 Hz mark

2100 Hz space

Receive answer: 390Hz mark

450Hz space

Fax Modulations V.21Ch2 FSK at 300 bps

V.27ter DPSK at 4800 and 2400 bps
V.29 QAM at 9600 and 7200 bps
V.17 TCM at 14400, 12000, 9600, and 7200 bps

Fax Carrier V.21 CH2 (half duplex)
Frequencies 1650 Hz mark, 1850 Hz space for transmit originate

1650 Hz mark, 1850 Hz space for transmit answer
V.27ter: 1800 Hz Originate/Answer
V.29 QAM: 1700 Hz Originate/Answer
V.17 TCM: 1800 Hz Originate/Answer

Chapter 1 - Introduction

Transmit Level -13 dBm
Frequency Stability +0.01%
Receiver Sensitivity -43 dBm under worst case conditions
AGC Dynamic 43 dB
Range
Serial Interface EIA RS-232C
Diagnostics Power-on self-test; ITU-T V.54 local analog loop, local digital loop, remote digital

loop.

13

Chapter 1 - Introduction

Firmware Upgrades Via flash PROM technology on Multi-Tech’s BBS
Indicators LEDs for Transmit Data, Receive Data, Carrier Detect, Speed, and Off Hook/Out-

Of-Service

Controls Toggle switches for busy-out
Environmental Temperature range: 0°–50°

Humidity range: 20–90% (noncondensing)

Power 5 VDC at 0.95 A
Requirements ±16 VDC at 0.1 A
Power Consumption Approximately 6 watts
Dimensions, .9 × 11 × 15 in. (2.2 × 28 × 37 cm) H × W × D
card modem
Weight 2.5 lb. (1.1Kg)
Limited Warranty Two years
Fuses F1 (+5V), F2 (-16V), F3 (+16V)

C (32°–120° F)

1.7 Power Supply

DC voltages are supplied to all modems in the CC4800A rack through one or two PS4800A power supplies,
designed for conventional 115 or 230 VAC connection. The power supply is a universal input switching
power supply.

14

Chapter 1 - Introduction

1.8 Modem LED Indicators

The MT2834MR6 has five LED indicators per modem:

TD Transmit Data. This LED blinks when data is being transmitted, on for a space, off for a mark. The

state of this LED matches that of the TD circuit on Pin 2 of the RS-232C interface.

RD Receive Data. This LED blinks when data is received, on for a space, off for a mark. The state of

this LED matches that of the RD circuit on Pin 3 of the RS-232C interface.

CD Carrier On. This LED lights when a valid carrier tone has been detected.

Speed Speed. This LED blinks at different rates to indicate the speed of the data connection:

Data Rate (bps) LED State

12000 or less Off
14400 or 16800 Slow blink rate
19200 or 21600 Medium blink rate
24000 or 26400 Fast blink rate
28800 or more On

OH/OOS Off Hook/Out of Service. This LED lights when the modem is off hook, which occurs when the

modem is dialing, online, or answering a call. The LED flashes when the modem is in the busy­out or out-of-service state.

Note: The PS4800 modem rack power supply has one LED that indicates the presence of all supply voltages.

1.9 Busy Switch

The MT2834MR6 has six two-position Busy switches on the front panel. Each switch can be used to create a
“busy-out” (OOS) condition for one of the six on-board modems (i.e., modem A, B, C, D, E, or F).

To place a modem in the Busy condition, move the appropriate Busy switch to the right. The selected modem
goes off-hook, its OH/OOS LED begins to flash, and incoming calls to this modem get a busy signal. If you
suspect a problem with a particular modem, you can use the Busy switch to have an optional device (such as
a “hunt group”) that looks for a non-busy line to perform a rollover to the next available modem while you
check the status of the Busy modem.

Note: The MultiModemManager can perform the same function using software.

15

1.10 MT2834MR6 Installation Notes

All installation must be done by a qualified service person.

Chapter 1 - Introduction

The installation instructions in your MultiModemManager
of blanking plates to cover empty slots in the card frame. Be sure to follow those instructions.

Warning: Interconnection directly, or by way of other apparatus, of ports marked “SAFETY WARNING see
instructions for use” with ports marked or not so marked may produce hazardous conditions on the network.
Advice should be obtained from a competent engineer before such a connection is made.

This product is intended to be hard wired to the network. The final connection to the network is the
responsibility of the public telecommunications network operator or a person authorized by that operator.

Any other apparatus, including cable and wiring, connected between the MT2834MR6K modem and the
point of connection to any speechband circuit shall comply with the following:

1. The overall characteristics of this apparatus shall be such as to introduce no material effect upon the
electrical conditions presented to one another by the modem and he speechband circuit.

2. The apparatus shall comprise only

a. apparatus approved for the purpose of connection between the modem and a speechband

circuit; and

b. cable and wiring complying with a code of practice for the installation of equipment covered by

this part of BS 6328 or such other requirements as may be applicable.

Note: Such apparatus may have been approved subject to limitations in its use.

Owner’s Manual

include information about the use

1.11 Safety Warnings

• Never install telephone wiring during a lightning storm.

• Never install telephone jacks in wet locations unless the jacks are specifically designed for wet locations.

• Never touch uninsulated telephone wires or terminals unless the telephone line has been disconnected at

the network interface.

• Use caution when installing or modifying telephone lines.

• Avoid using a telephone (other than a cordless type) during an electrical storm. There may be a remote

risk of electrical shock from lightning.

• Do not use the telephone to report a gas leak in the vicinity of the leak

• Ports that are connected to other apparatus are defined as SELV. To ensure conformity to EN 41003,

ensure that these ports are only connected to the same type on the other apparatus.

16

Chapter 2 - Dialing and Answering

Chapter 2 - Dialing and Answering

2.1 Introduction

This chapter describes the dialing and answering capabilities of the MT2834MR6 modems, which are
standard ITU-T V.34 full duplex dial-up modems.

2.2 Dial-Up Automatic Answering

The MT2834MR6 can answer calls automatically. The MT2834MR6 is in originate mode in its idle state.
When it detects an incoming call, it automatically switches to answer mode. You can program the modem to
answer a call after a certain number of rings by using register

S0

(see Chapter 4).

2.3 Dial-Up Handshaking Details

This section briefly explains what happens between two modems in a normal call. We are assuming that
there are MT2834MR6s at both the originating and at the answering end of the telephone line. (If other
brands of modems are used with our modems, they will still communicate, but each manufacturer tends to
use slightly different delay timings and sequences, and many of the brands vary in their indicator
designations.)

Before V.34 negotiation takes place, remote and local modems transfer their functional capabilities using
modulated calling and answering tones. First, the Calling Menu (CM), a data sequence using V.21 low-band
modulation (a handshaking technique originally developed for 300 bps modems), is sent from the originating
V.34 modem to the answering V.34 modem. This describes the range of functional capabilities the originating
modem supports. The answering V.34 modem responds to the CM with a Joint Menu, or JM (using V.21 high­band modulation), indicating the common capabilities of the modem at each end.

Once this is done, a probing signal is passed between the modems to identify impairments in the telephone
channel. After receiving the results of the probing signal, the modem receivers and transmitters will start with
the lowest speed and move up until reaching the highest speed at which they can exchange data. All this
occurs in about five seconds.

Note: In order for the called modem to be able to answer the call, it must have a high DTR (Data Terminal
Ready) signal on pin 20 of the RS-232C interface. This signal comes from the computer or terminal to which
the modem is connected.

Note: If you are using reliable or auto-reliable mode, some additional handshaking takes place. This is
explained in Chapter 5, in the “Auto-Reliable Mode” section.

18

Chapter 2 - Dialing and Answering

2.4 Call Termination

There are several methods by which you can terminate a call, or simply stated, hang up:

1. Command Mode Control. It is possible to enter command mode while remaining online by entering an
escape sequence (
by typing
(bring it on-hook). So the command to hang up a call is three plus signs followed by

2. DTR Control. If DTR (Data Terminal Ready) is turned off for 50 milliseconds or more, a disconnect will
occur. This is probably the most common method used by computer systems at the autoanswer end of
the line to cause the calling modem to disconnect after logoff procedures.

3. Loss of Carrier. Once a data connection has been established, the modem will disconnect if a loss of
carrier occurs for 700 milliseconds (0.7 seconds) or longer. This time can be configured with register
for any time from 0 to 25.5 seconds (in 100 mSec increments). Note that one cause of carrier loss would
be if one of the modems were to disconnect normally.
has no effect at connections above 2400 bps.

4. Abort Timer. Answer Mode: When OH (Off Hook) comes on, the called modem starts a 45 second timer
and waits for a carrier signal from the originating modem. If a carrier is not detected within this period, the
modem disconnects (hangs up) and is ready for another call. Originate Mode: The abort timer functions
the same as in the answer mode, except that the timer begins after the modem has completed dialing,
instead of when it first goes off hook. It is possible to change this 45-second wait period to any other
value from 1 second up to 254 seconds by reconfiguring register

5. Inactivity Timer. Causes the modem to disconnect if no data is being transmitted or received for a
certain period of time. The timer is reset anytime a character passes through the serial port in either a
send or receive direction. This function is controlled by register
by setting
by register

ATO

S30

S30

+++AT<CR>

, or you can terminate the call by using the H command. Typing

to 0, which is the factory default setting, or set to time out after number of minutes selected

.

in most cases). From command mode, you can return to the online state

ATH

will hang up the line

ATH

.

S10

S10

works for speeds of 2400 bps or below.

S7

(see Chapter 4).

S30

. The inactivity timer can be disabled

S10

19

Chapter 3 - AT Commands

Chapter 3 - AT Commands

3.1 Working with AT Commands

The MT2834MR6’s modems are controlled by instructions called AT commands, so called because the
attention characters AT precede each command or command string (sequence of commands). You can send
commands to the modem from your keyboard while in terminal mode, or you can use communications
software to issue these commands automatically.

The MT2834MR6 is in command mode when it is not dialing or online. When it is in command mode, you
have access to a complete communications system that allows you to use several features, including the
basic AT command set described in this chapter. Using the basic AT command set, you can enter phone
numbers for automatic dialing, configure modem options, and monitor telephone activity. In addition, you can
command your modem to perform advanced features such as error correction, data compression, speed
conversion, and more.

This chapter explains command mode, and shows you how to use each of the MT2834MR6’s AT commands.
MT2834MR6 commands and responses are compatible with all systems and with all data communications
software using the AT command set.

For easy reference, the MT2834MR6 has a help command that provides you with short, on-screen
descriptions of the modem commands. The help command is explained later in this chapter.

3.1.1 Modes of Operation

The MT2834MR6 operates in two basic functional modes: command mode and online mode. (There is also
an in-between state, wait-for-carrier, in which the modem is out of command mode but not yet online.) When
you power up the modem, it is in command mode, and is ready to accept and respond to commands from
your keyboard or software.

An MT2834MR6 modem enters online mode after it dials, connects with another modem, and detects a valid
carrier signal. If it does not detect a carrier signal within the time frame controlled by register S7, the modem
abandons the call and re-enters command mode.

You can make the modem enter online mode without dialing by typing either the D command or the A
command.

The modem exits online mode if the carrier signal is lost or intentionally dropped. When this happens, the
modem hangs up and re-enters command mode.

By sending certain “escape” characters to the modem while online, you can make it enter command mode
without losing the carrier signal.

For autoanswer-only applications, you can disable a modem’s ability to recognize AT commands by using
the %DC1 command. When you do this, the MT2834MR6 ignores all commands, and functions as a non­intelligent modem. The %DC1 command and other MT2834MR6 commands are explained later in this
chapter.

21

Chapter 3 - AT Commands

3.2.2 Command Structure

You can control a wide variety of modem operations and options when the modem is in command mode. AT
commands tell the modem to dial a number, to answer a call, to operate at a certain speed, to use a certain
compression technique, and many other functions. AT commands consist of one or two letters, which may be
preceded by an ampersand (&), a dollar character ($), a pound character (#), a percent character (%), or a
greater-than character (>). The Q command, for example, determines whether the modem returns result
codes, while the &Q command selects which AT command set the modem uses.

A parameter after a command (0, 1, 2, etc.) tells the modem which option to use. If you do not specify a
parameter, the modem assumes the 0 (zero) option. E, for example, is the same as E0. You can issue several
commands on a single line (a command string) as long as the line does not exceed 60 characters. Note that
though Q1 is one command, it counts as two characters in the command line.

Each command has a valid range of parameters; for instance, &W can have only 0 or 1 as a parameter. Valid
commands generate an OK result code. A few generate an additional response, such as a list of parameters.
An invalid command, such as &W3, which has a parameter outside the valid range, generates an ERROR
result code. Most commands have a default parameter, one that is enabled when the modem is turned on or
reset with the ATZ or AT&F command. Factory defaults are stored in read-only memory (ROM), and cannot
be changed. User-defined defaults can be stored in nonvolatile random-access memory (NVRAM), and can
be changed or deleted at will.

3.3.3 Command Editing

Always begin a command with the letters AT. You may type the command in upper case or lower case, but
not both. The AT command is not executed until you press the ENTER key. Use the BACKSPACE key to
erase the previous command character; it will not erase the AT characters once they are typed. If your
keyboard has no BACKSPACE key, use CTRL+H. You can change the character recognized by the modem
as BACKSPACE to any other ASCII character by changing register S5.

To cancel an entire command that has been typed but not yet executed, press CTRL+X. This also clears the
command buffer. The effect is the same as backspacing the command, only quicker.

The MT2834MR6 stores characters entered in a command in the modem’s command buffer until they are
executed by pressing ENTER. The command buffer’s capacity is 60 characters. The attention characters (AT)
do not count in the 60 allowed command characters. You may use spaces for increased readability when
typing a command; they are neither stored in the command buffer nor counted in the 60 allowed characters.
Hyphens, parentheses, etc., are not allowed.

If you exceed the 60-character limit or type invalid characters, the command buffer is automatically erased
and an ERROR message is displayed. You must then retype the command within the 60-character limit,
using only the allowed characters.

The commands in this chapter are organized by function. A brief summary follows.

22

Table 3-1. AT Commands by Function
Topic: Command: Description:
Dialing Action D Dial

A: Continuous redial
H On-hook/off-hook

Dial Modifiers P Pulse dialing

T Tone dialing
W Wait for new dial tone
R Reverse originate/answer mode
, Dialing pause
: Continuous redial
; Return to command mode after dialing
! Flash on-hook
@ Quiet answer
$ Call card tone detect

Phone Number D...N Store a phone number
Memory N Dial a stored number

N...N Number linking
L List stored telephone numbers

Chapter 3 - AT Commands

Configuration &W Store configuration
Storage & Recall &F Load default configuration

Z Reset modem

Modem Responses E Echo command mode characters
(Result Codes) Q Result codes: enable/disable

&Q Result codes: Multi-Tech or standard
V Result codes: verbose/terse
X Result codes and call progress
&A Answerback

Online Connection #A Auto speed detection

B Answer tone
%DC Command mode control
&CD Cleardown at disconnect
>DT DTMF detection
#F Fallback modes when online
&G Guard tones
*H Busy-Out After Disconnect
&P Pulse dial ratios
&RD Square wave ring detect
$T Calling tones
#T Trellis-coded modulation
Y Long space disconnect

23

Chapter 3 - AT Commands

Table 3-1. AT Commands by Function (con't)
Topic: Command: Description:
V.34 Controls %F Echo canceler frequency offset comp.

&RA Asymmetric bit rate
#V V.32terbo handshake

RS-232 Interface &C Carrier Detect control
Controls &D Data Terminal Ready control

&R Clear to Send control
&S Data Set Ready control
&RF CTS/RTS interaction control
&SF DSR/CD interaction control

Error Correction & &E0 Non-error correction mode
Data Compression &E1 Autoreliable mode

&E2 Reliable mode
&E14 Data compression disabled
&E15 Data compression enabled
#L V.42 error correction modes
$E V.42 error correction at 300 bps
$A Autoreliable buffering
$F Autoreliable fallback character enable
$R Retransmit count

Speed Controls $BA Baud adjust

$MB Modem baud rate
$SB Serial port baud rate

Immediate Action A/ Repeat last command

I Inquire product code
L5 List current operating parameters
L6 List S-register values
L7 List current operating parameters
L8 List online diagnostics
&RN Rate renegotiation
&RR Retrain

Flow Control &BS Maximum reliable block size

$EB Asynchronous word length (10/11-bit)
&E3 Flow control disabled
&E4 Hardware flow control
&E5 XON/XOFF flow control
&E6 XON/XOFF no pass-through
&E7 XON/XOFF pass-through
&E8 Hewlett Packard ENQ/ACK pacing off
&E9 Hewlett Packard ENQ/ACK pacing on

24

Chapter 3 - AT Commands

Table 3-1. AT Commands by Function (con't)
Topic: Command: Description:

&E10 Non-error correction mode flow control off
&E11 Non-error correction mode flow control on
&E12 Pacing off
&E13 Pacing on
#X Number of XOFF characters sent

Escape +++AT<CR> Default in-band escape sequence
Sequences <BREAK>AT<CR> Alternate out-of-band escape sequence

%E Escape sequence selection
A Force answer mode
O Go back online

Remote %%%AT<CR> Remote configuration escape sequence
Configuration #I Change login password

#S Change setup password

Line Probes %DP Read line probe data

%DF Format line probe data
&RP Immediate line probe
L9 Display signal strength
L10 Display signal to noise ratio
L11 Display noise strength

Diagnostics &T Respond to remote digital loopback signal

U Loopback test modes

25

3.2 Dialing Commands

Dialing commands are used to dial and to hang up.

Ds Dial

s = phone number
Default: none

The letter D in a command causes the modem to dial the telephone number immediately
following it. For example, if you type ATD5551212<CR>, the modem dials the number 555-

1212.
The MT2834MR6 supports several dialing methods. With the D command, you can specify
either pulse (ATDP) or tone (ATDT) dialing. You can also modify the dialing command with
several characters that are explained in “Dial Modifier Commands” in this chapter.
The MT2834MR6 lets you select either smart (wait-for-dial-tone) dialing or blind dialing.
With smart dialing, the modem waits for and detects dial tones and busy signals. With blind
dialing, the modem works with timed pauses (determined by the value of register S6), not
dial tone and busy signal detection. See the X command for more information on blind and
smart dialing.

A: Continuous Redial

If you select smart dialing through the X3 or X4 command, the A: command lets you
continuously redial a busy number until your call is answered. (North American units have a
maximum of 10 redials; this command is not available on U.K. or International models.)
Use this command only if you have reached a busy number after executing a normal dial
command. Type A: (you need not type AT, nor do you need to press ENTER), and the
modem redials the number. If you again reach a busy signal, the modem continues to redial
until it gets through. You can stop the modem from redialing by pressing any key.
To save a step when redialing a phone number, enter a colon (:) at the end of the phone
number. The result is the same as if you had entered A:

Chapter 3 - AT Commands

Note: This command has been largely superseded by software-based continuous redial features.

Hn On-Hook/Off-Hook

n = 0 or 1
Default: none

You can make the modem go on-hook (hang up) or go off-hook with the H command.
H0 (or H) hangs up the modem
H1 brings the line off-hook, just as if you had picked up the telephone handset.

It is not necessary to use the H1 command to bring the line off-hook when using the D
command. The modem automatically goes off-hook when you press ENTER at the end of
the dial command.

26

Chapter 3 - AT Commands

3.3 Dial Modifier Commands

The dial string can include the digits 0 through 9, the pound sign (#), the asterisk (* ), and the letters A, B, C,
or D. The latter are used by some PBXs; the exact function will depend on the PBX manufacturer’s feature set
and implementation. There are also several command characters, called “dial modifiers,” that can be
included within a dialing command after the letter D. Their functions include pulse or tone dialing, pauses in
the dial sequence, automatic redials if a number is busy, and reverting to command mode or switching to
answer mode after dialing.

P, T Pulse or Tone Dialing

Default: P

The MT2834MR6’s modems can dial numbers by using pulse dialing, tone dialing, or a
combination of both methods. Pulse dialing, used by rotary-dial telephones, uses the timed
opening and closing of a relay to encode the numbers. Tone dialing, used by push-button
(touch-tone) telephones, uses dual tone multifrequency (DTMF) dialing.

P selects pulse dialing.
T selects tone dialing.

Insert P or T in the dialing command just before the digits you want to pulse- or tone-dial.
For example, to pulse-dial the number 555-1212, type ATDP5551212 and press ENTER.
To tone-dial the same number, type ATDT5551212 and press ENTER. If neither pulse nor
tone dialing is specified in the dial command, the modem uses whatever method was used
last.
Immediately after the modem has been turned on or reset, it uses pulse dialing, even if you
do not include P in your dial command.
As an example of combining pulse and tone dialing, assume you are calling out of a PBX
(switchboard) system where a 9 has to be pulse-dialed, then the rest of the number has to
be tone-dialed after pausing for a second dial tone. To dial this example, type

ATDP9,T5551212 and press ENTER. (The comma causes a pause.)

W Wait for New Dial Tone

Inserting W into the dialing command causes the modem to wait for another dial tone before
it resumes dialing. (It is not necessary to enter W at the beginning of the dialing command.)
Because the modem must be able to detect the dial tone for this command to work, you also
must select wait-for-dial-tone dialing with the X2 or X4 command.

Rn Reverse Originate/Answer Mode

n = 0 or 1
Default: R0

The R command lets you reverse the modem’s mode of operation from originate to answer,
or from answer to originate; for example, if you need the modem to answer the phone but
then go into originate mode.

R (with no number) at the end of the dialing string reverses in originate mode.
R0 disables mode reversing.
R1 enables mode reversing when R is added to the dial string.

27

Chapter 3 - AT Commands

, Dialing Pause

Enter a comma in the dialing string to make the modem pause while dialing. This pause
lasts two seconds (North American models) or four seconds (U.K. and International models)
for each comma entered. You can force longer pauses by entering multiple commas, or you
can change the length of the pause caused by a comma by setting register S8 to any value
from 0 through 255 seconds (North American models), 4 through 7 seconds (U.K. models)
or 4 through 255 seconds (International models).
Each comma in a dialing command counts as one of the 60 allowed characters.

: Continuous Redial

Enter a colon (:) as the last character of a dialing command, to cause the modem to
continuously redial the number, if it detects a busy signal, until the call is answered. North
American models are limited to 10 redials. You must select smart dialing (X3 or X4) for this
to work. (Not available in U.K. or International models.)

Note: This command has largely been superseded by software-based continuous redial features.

; Return to Command Mode After Dialing

Enter a semicolon (;) as the last character of a dialing command to cause the modem to
return to command mode immediately after executing the command instead of waiting for a
carrier signal and going online.
For example, type ATDT5551212; to tone-dial the number and immediately go back into
command mode. The semicolon is useful when modem data transfer is not desired, as in
voice communications, or in applications using touch tones as a data entry method, such as
bank-by-phone.

! Flash On-Hook

Some switchboard systems react to a momentary on-hook condition. Insert an exclamation
mark into the dialing command to cause the modem to “flash” on-hook for half a second,
just as if you had pressed the switch hook on a telephone set for half a second. (With U.K.
models, the exclamation mark causes the modem to flash on-hook for 90 milliseconds.)
For example, to flash on-hook to transfer to extension 5678 after dialing the number 555­1234, type ATDT5551234,,!5678. The commas cause a 4-second pause.

@ Quiet Answer

Use the @ command to access a system that does not provide a dial tone. The @ command
causes the modem to wait before processing the next character in the dialing string. The
wait is for one or more rings back followed by five seconds of silence.
For example, ATDT5551212@6313550 causes the modem to dial the first number (555-

1212), then wait for the time specified in register S7 for at least one ringback and five
seconds of silence. If the modem detects a busy signal, it hangs up and generates a BUSY
result code. If it does not detect five seconds of silence, it hangs up and generates a NO
ANSWER result code. If it does detect five seconds of silence, it dials the second number
(631-3550).

28

$ Call Card Tone Detect

Use the $ command to dial services that require you to enter your call card number after a
tone. A $ character in the dialing string causes the modem to pause and wait for an AT&T
call card “bong” or a 1600 Hz tone (prevalent in the U.K.). When the modem detects the
tone, it processes the rest of the dialing string. If it does not detect a tone within the time set
by register S7 (a 45-second default), the modem aborts with a NO CARRIER message.
Pressing any key also aborts the $ command.
In the following example, the $ command is placed between an access/phone number and
the caller’s credit card number:

ATDT1028806127853500

Chapter 3 - AT Commands

$123456789

29

Chapter 3 - AT Commands

3.4 Phone Number Memory Commands

The modem can store up to two telephone numbers in nonvolatile memory. You can store the numbers with
the DsNd command, dial them with the Nd command, link them so that one will be automatically dialed after
the other with the NdNe command, or list them with the L command.

DsNd Store a Phone Number

s = phone number
d = 0 or 1
Default: none

You can store a telephone number command string of up to 60 characters in the modem’s
phone number memory. You can store two of these 60-character strings using the DsNd
command. The memory locations are labeled N0 and N1.
Store a command line by typing it as you would any other command, appending the
appropriate Nd memory location.
For example, the tone-dialed number 1-612-555-1212 is stored at memory location N0 by
typing ATDT16125551212N0 and pressing ENTER. The number is not dialed with this
store command.
After storing a number, check to see that it has been stored correctly by typing ATL and
pressing ENTER.
When you store a phone number, you store the entire command string, so you can
effectively create a macro for each number. For example, if you know a particular number
needs to have extended result codes, detect busy or dial tone, error correction, XON/XOFF
flow control, pacing, and data compression enabled, the command to store the entire
command string at location N0 is ATX4&E1&E5&E13&E15DT16125551212N0.

Nd Dial a Stored Number

d = 0 or 1
Default: none

You can automatically dial a telephone number that is stored in the modem’s number
memory by typing ATNn, where n = 0 or 1. For example, you can dial a number stored at N0
by typing ATN0 in terminal mode and pressing ENTER.

Warning: Do not include the letter D in this command, or the stored number will be erased.

NdNe Number Linking

d = 0 or 1
e = 1 or 0
Default: none

Number linking allows the modem to dial a second stored number if the first stored number
is busy. (See the DsNd command.) This command is useful when a computer can be
accessed through more than one phone number. However, it cannot be used with blind
dialing, since busy signals would not be detected.
To link the number in memory location N0 to the number in N1, type ATN0N1 and press
ENTER. You can cycle back and forth between two numbers by linking them several times
in one command: ATN0N1N0N1N0N1<CR>. The only limit on the number of times the
modem can cycle between two numbers is the 60-character maximum allowed in a
command line.

30