Multi-Tech Systems MT2834BR, MT2834BLR User Manual

MT2834BR/MT2834BLR

Intelligent Data/Fax

Rack Mounted Modem

User Guide

MT2834BR/MT2834BLR User Guide
PN: S000316

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 11/15/2003 Initial release of MT2834BR/MT2834BLR as a

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

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combined User Guide.

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[phone] or [phone]
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Technical Support [phone]
www.multitech.com

Contents

Chapter 1 - Introduction................................................................ 5

1.1 Introduction .............................................................................. 6

1.2 Features ................................................................................... 6

1.3 How to Use This Manual ......................................................... 7

Chapter 2 - Installation.................................................................. 8

2.1 Preliminaries ............................................................................ 9

2.1.1 Card Cage.................................................................... 9

2.1.2 Serial Cable ................................................................. 9

2.1.3 Telephone Line ............................................................ 9

2.2 Installation .............................................................................. 10

2.3 PC Board Controls ................................................................. 11

2.3.1 DIP-Switch Settings................................................... 12

2.4 OOS (Busy Out) Toggle Switch ............................................ 14

2.4.1 Out of Service/Test Jumper ...................................... 15

2.4.2 MI/MIC Option Jumper .............................................. 15

2.5 Dial-Up and Leased Lines ..................................................... 16

2.6 Modem LED Indicators .......................................................... 17

Chapter 3 - Installation................................................................ 19

3.1 Introduction ............................................................................ 20

3.2 Serial Port Limitations ............................................................ 20

3.2.1 How Can You Identify Your UART Type? ................ 21

3.3 Configuring Your Software .................................................... 23

3.3.1 ConfiguringSoftware for Your Modem ...................... 23

3.4 PC Initialization Strings ......................................................... 24

3.4.1 Changing Default Parameters................................... 26

3.5 Macintosh Initialization .......................................................... 26

3.6 Configuring Software for Your Computer ............................. 27

3.6.1 Configuring Software for the Remote System.......... 28

3.6.2 Terminal Emulation .................................................. 28

3.6.3 File Transfer Protocols .............................................. 29

3.7 When to Disable Data Compression..................................... 29

3.7.1 Disabling Error Correction......................................... 30

Chapter 4 - ModemCommands................................................... 31

4.1 Modem AT Commands.......................................................... 32

4.1.1 Callback Security Commands ................................... 43

4.1.2 Remote Configuration ............................................... 45

4.1.3 Remote Configuration Procedures ........................... 45

4.1.4 V.25bis Commands ................................................... 46

4.2 S-Registers............................................................................. 48

4.3 Result Codes.......................................................................... 52

4.3.1 AT Commands and S-Register Summary ................ 55

Chapter 5 - Modem Testing ........................................................ 56

5.1 Local Analog Loopback Test/V.54 Loop 3............................ 57

5.2 Digital Loopback Test/V.54 Loop 2

(Local/Manual) ....................................................................... 58

5.3 Digital Loopback Test/V.54 Loop 2

(Remote/Automatic)............................................................... 60

5.4 Local Analog Loopback Test

(Synchronous Mode).............................................................. 61

5.5 Digital Loopback Test (Local/Manual)

(Synchronous Mode).............................................................. 62

5.6 Digital Loopback Test (Remote/Automatic)...............................

(Synchronous Mode).............................................................. 63

Chapter 6 - Warranty and Service.............................................. 64

6.1 Introduction ............................................................................ 65

6.2 Limited Warranty.................................................................... 65

6.3 Tech Support.......................................................................... 66

6.3.1 Recording Modem Information .................................. 66

6.3.2 Service ....................................................................... 66

6.4 Upgrading the MT2834BR..................................................... 67

6.4.1 Using FlashPro to Upgrade Modem Firmware......... 67

6.5 Safety Warnings..................................................................... 68

6.6 Internet ................................................................................... 69

Chapter 7 - BABT Requirements................................................ 70

7.1 Compliance with BABT Requirements.................................. 71

7.1.1 European Low Voltage Directive .............................. 72

7.1.2 Compliance with BS6305 Clause 6.2, BS6320

Clause 7.2, and BABT/SITS/82/005S/D................... 72

7.1.3 Compliance with BS6789: Section 3.1 and Part 2 ... 73

7.1.4 Compliance with BS6328 Part 1 ............................... 74

Appendices ................................................................................... 75

Appendix A ..................................................................................... 76

FCC Regulations for Telephone Line Interconnection........ 76

Canadian Limitations Notice ................................................. 78

Appendix B ..................................................................................... 79

Technical Specifications ........................................................ 79

Index .............................................................................................. 84

Chapter 1 - Introduction

Chapter 1 - Introduction

1.1 Introduction

Welcome to the world of data communications. You have acquired one of
the finest intelligent data/fax modems available today, either the model
MT2834BR or MT2834BLR (MT2834), from Multi-Tech Systems. Your
MT2834 modem provides data communication at 33,600-14,400 bps
(*Enhanced V.34/V.32bis), as well as other prevalent datacomm standards.
The MT2834 also includes adaptive protocol enhancing used in typical

TM

Unix® batch file transfers and support for IBM's AS/400 (iSeries)
System3x

TM

environment. The MT2834BLR provides support for dial back-

and

up with automatic leased line restoral. This User Guide will help you install,
configure, test and use your MT2834 data/fax modem.

*Note enhancements on V.34 code (33.6K/31.2K) is awaiting formal ITU
approval; the ITU study group 14 has agreed on the technical side of the
proposal, with formal approval expected at the next ITU meeting in
Geneva.

1.2 Features

The MT2834 automatically adjusts to line conditions and the capabilities of
the modem it connects to, resulting in the highest possible speed, the most
accurate error correction, and the most efficient data compression possible
for each connection. The MT2834 is designed for data rates as high as
33,600 bps in full-duplex mode over public telephone lines.

MT2834 features include:

· Support of data rates of 33,600, 31,200, 28,800, 26,400, 24,000, 21,600,
19,200, 16,800, 14,400, 12,000, 9600, 7200, 4800, 2400, 1200, 0-300
bps.

· Automatic fallback to slower speeds in noisy line conditions, and fall­forward to faster speeds as conditions improve.

· ITU-T V.42 LAP-M and MNP Classes 3 and 4 error correction.

· Data transfer rates up to 115,200 bps with V.42bis 4-to-1 data
compression.

6

· Automatic disabling of compression when transferring already­compressed files.

· Serial port data rates adjustable to 115.2K bps.

· Autodial, redial, pulse (rotary) and touch-tone dial.

· Dial tone and busy signal detection for reliable call-progress detection.

· Compatibility with the standard AT command set used by most
communication programs.

· On-screen help menus.

· Nonvolatile memory for storage of customized modem parameters and
ten telephone numbers.

· Sends and receives faxes from your computer at 14,400, 9600, 7200 or
4800 bps.

· Responds to EIA TR.29 Class 2 fax commands.

· Supports UNIX-to-UNIX® UUCP Spoofing.

TM

· Supports IBM's AS/400 (iSeries)

and System3x environment.

1.3 How to Use This Manual

This chapter begins with a short introduction, a profile on modem features,
followed by a guide (which you are now reading) to the use of this manual.
This manual includes hardware installation and configuration described in
Chapter 2. Chapter 3 covers communication software configuration
recommended for the MT2834. Other issues covered include setting up
initialization strings, changing default parameters, configuring software for
the remote system and file transfer protocols. Chapter 4 covers modem AT
commands, Remote Configuration commands, S-Registers and Result
Codes. Chapter 5 illustrates the MT2834 diagnostic capabilities, providing
Analog and Digital Loopback testing procedures. Chapter 6 explains
product warranty and technical support. Appendices A and B respectively
describes FCC requirements and regulations and technical specifications.

Chapter 2 - Installation

Chapter 2 - Installation

2.1 Preliminaries

This chapter covers MT2834 installation and connection. In addition to the
contents of the MT2834 package, you will need the equipment listed
below.

2.1.1 Card Cage

The MT2834 is designed to mount in the Multi-Tech Systems' modem rack
(see Section 2.2 for various models available). This rack is an EIA­standard 19-inch wide by 7-inch high rack, and mounts in any standard
computer cabinet. The rack has a sixteen modem slot capacity, one power
supply source (the CC1600 series card cage has a redundant power
supply capability), sixteen 25-pin (female) connectors for RS232C/V.24
interface and sixteen DB9 (female) connectors for phone line (the CC1600
series card cage has RJ11 back-plane connectors for phone line interface).

2.1.2 Serial Cable

You must provide a serial cable to connect each corresponding MT2834 to
your computer. The cable must have a DB-25 male interface into the
modem rack.

2.1.3 Telephone Line

The MT2834 uses one RJ11 jack per corresponding modem slot to
connect to the telephone lines. To connect the modem to the phone lines,
plug one end of the RJ11 cable that is provided with the modem into the
DB9 (9-pin connector) located on the back plane of the modem rack and
the other end into the phone-company-provided RJ11 or RJ11W modular
phone jack (CC916, CC1416 or CC2816 racks). To connect the modem to
the phone lines using the CC1600 modem rack, plug one end of the RJ11
cable provided with the modem into the rack's RJ11 connector (located on
the back plane of the modem rack) and the other end into the phone­company-provided RJ11 or RJ11W modular phone jack.

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Chapter 2 - Installation

2.2 Installation

Perform the following procedure to install modem cards in the CC916,
CC1416, CC2816 or CC1600 racks*. The installation process involves:

1. Power cord must be unplugged prior to installation of the Power

Source(s). Insert Power Source(s) (PS216A or PS1600) into far right of
the rack cage.

2. Slide a modem card into one of sixteen available modem slots. Start by

inserting a modem into the left-most channel (slot #1) of the rack. The
toggle switch should be at the bottom of the card, with the component
side of the card facing the right. The modem’s gold edge connector is
offset so that the modem cannot be inserted incorrectly. Continue
installing modem cards as necessary.

3. Plug RS232C Cable into appropriate modem slot (DB25/25-pin

connector-female) at rear of rack. Note: Any cables connected to the
computer must be shielded to reduce interference.

4. If you are connecting your phone line directly to the modem card, plug

the phone line cable into the appropriate modem slot (DB9/9-pin
connector-female) at the rear of the rack and the other end into the
phone-company-provided RJ11 or RJ11W modular phone jack. To
connect the modem to the phone lines using an CC1600 modem rack,
plug one end of the RJ11 cable provided with the modem into the rack's
RJ11 connector (located on the back plane of the modem rack) and the
other end into the phone-company-provided RJ11 or RJ11W modular
phone jack.

5. Plug in modem rack power cord.

6. Verify remote modem's current configuration settings with your

MT2834BR in terms of data compression, error correction, transmission
rate, etc. (ATL5/ATL7 Command - see Chapter 4 on AT commands).

7. Attach MT2834BR to dial-up phone lines and/or leased lines and verify

DIP-Switch #10 and #5 settings (Section 2.5).

8. Make sure modem and computer/terminal serial port baud rates are

adjusted (Section 2.5.).

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Chapter 2 - Installation

9. Set both local and remote modems to either Normal (&E0&W0) mode

or to Reliable (&E2&W0) mode.

10. Verify leased line transmit level (DIP-Switch #3) setting (Section 2.3.1).

11.Proceed to Chapter 3 of this manual, or to your data communications

software manual.

* All Multi-Tech rack-mounted modem cards (except MT1432/2834) are

interchangeable among all types of modem racks. There is, however, slight
LED differences. Model #CC216G is a “generic” modem rack for any rack
mount modem card. The user affixes LED labels on a per slot basis depending
on modem type.

2.3 PC Board Controls

The MT2834 is designed on a single printed circuit board. This board
contains sixteen DIP-Switches. There is a two-position"Out of Service"
(OOS) toggle switch that extends from the front of the modem circuit card.
There is also a two-position MI/MIC berg jumper and TEST/OOS berg
jumper.

11

Chapter 2 - Installation

The sixteen DIP-Switches and two berg jumpers control various modem
options or set default values for the MT2834 Command mode. There is a
difference in how several of the switches operate depending on whether
you are in synchronous or asynchronous mode (DIP-Switch #12).

Most communications software packages have installation procedures of
their own, which call for certain modem DIP-Switch settings. If you are
using a package other than MultiExpress, follow the software's instructions.

2.3.1 DIP-Switch Settings

The vast majority of installations are similar, with the MT2834 being used
to dial up a remote installation where the call is automatically answered.
The factory default DIP-Switch settings are based on this assumption. The
following is a brief description and summary of the MT2834's DIP-Switch
options:

Switch Function Position Effect

#1 DTR Forced/ UP* DTR forced from

DTR from Interface * DOWN computer/terminal

#2 Flow Control &E4* UP* Hardware flow

(Async/Dial-Up/Leased Line) DOWN control enabled

#2 SDLC*/BSC (Sync) UP* SDLC enabled

DOWN

#3 Result Codes Enabled* UP Modem responses

(Async Dial-up) DOWN* are echoed

#3 DbM Transmit -15dB/-11dB* UP Lease Line

(Async/Sync/Leased Line) DOWN* transmits at -11dB

#4 UUCP Disabled* (Async UP* UUCP

Dial-Up/Leased Line) DOWN "spoofing" Disabled

#4 AS/400 Mode Disabled* UP* AS/400 Mode

(Sync Dial-Up/Leased Line) DOWN Disabled

#5 Auto-Answer Enabled* UP* Auto-Answer

Async/Sync/Dial-Up) DOWN in dial-up mode

* Factory default setting.

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Chapter 2 - Installation

Switch Function Position Effect

#5 Answer/Originate* UP* Originate call in

(Async/Sync/Leased Line) DOWN Lease Line mode

#6 Max-Throughput Enabled* UP* Modem set-up to

(Async/Dial-Up/Leased) DOWN operate at highest

efficiency level

#6 Slave Clock Disabled* UP* Clock controlled

(Sync/Dial-Up/Leased) DOWN by remote device

#7 RTS/Normal/Forced* UP RTS Forced On

(Sync/Async/Dial/Leased) DOWN*

#8 Command Mode Enabled* UP Command Mode

(Sync/AsyncDial/Leased) DOWN* Enabled

#9 Local/Remote LoopBack* UP Remote

(Async/Sync/Dial/Leased) DOWN* LoopBack Enabled

#10 Dial-Up*/Leased-Line UP* Dial-Up Enabled

DOWN

#11 "AT"/Multi-Tech Result Codes UP Multi-Tech Result

(Asynchronous) DOWN* Codes Enabled

#11 Internal*/External Clocking UP Selects Transmit

(Synchronous) DOWN* Clock Source

#12 Sync/Async Mode* UP Async Enabled

DOWN*

13

Chapter 2 - Installation

Dip Switch Settings #13 - 16

Note: A modem baud rate command (e.g., $MB33600) overrides the
setting of the speed selection switches (#13 and #14).

Switch Position Effect

13/14 UP/UP* 28.8 K bps Operation (Default)
13/14 DOWN/UP 19.2 K bps Operation
13/14 UP/DOWN 14.4 K bps Operation
13/14 DOWN/DOWN 9600 bps Operation
#15 UP* CD/DSR from Interface

#15 DOWN CD/DSR Forced On
#16 UP Used in combination with

#16 DOWN DIP-Switch #9/Loopback Tests

* Factory default setting

2.4 OOS (Busy Out) Toggle Switch

The MT2834 contains a two-position OOS switch on the front panel. This
switch can be used to create a “busy out” (OOS) condition for the modem
(i.e., take the modem off-hook). To place a modem in the Busy condition,
move the OOS toggle switch to the (BUSY) position. The modem then
goes off-hook, its OOS and OH LEDs light, 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 “roll over” to the
next available modem while you check the status of the Busy modem.

14

Chapter 2 - Installation

2.4.1 Out of Service/Test Jumper

When the MT2834 is Out Of Service (OOS), it is busy to incoming calls. In
the Test (default) setting, the modem drives pin 25 high when the modem
is in Test mode. In the OOS (optional) setting, the computer or terminal
forces pin 25 high and puts the modem in a busy condition. Note that
jumper (shorting) plugs are not shipped with the MT2834, but is provided
by Multi-Tech’s Tech Support group on request.

Test Setting

(Factory Default)

OOS Setting

(Optional)

2.4.2 MI/MIC Option Jumper

To activate MI/MIC option (Mode Indicate/Mode Indicate Common
Interface), you must first move MI/MIC jumper plugs. The $MI command,
then controls this function (AT$MI1 enables MI/MIC and AT$MI0 disables
MI/MIC). This option is for applications where the modem's dialing
capability is not used, and dialing is done by an external device (such as a
801 dialer, a computer, or a PBX/CBX system dialer).

MI/MIC MI/MIC

MI/MIC Disabled

(Factory Default)

MI/MIC Enabled

(Optional)

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Chapter 2 - Installation

2.5 Dial-Up and Leased Lines

Connection to the phone system is made via RJ11 type jacks such as an
RJ11C or RJ11W. It can also be connected to an RJ41 or an RJ45S jack,
but would not use these jack's dB-level programming features. The
MT2834 is designed to transmit at a permissive level of -11dB.

To connect the modem to the phone lines, plug one end of the RJ11 cable
that is provided with the modem into the corresponding DB9 or RJ11
connector (dependent upon card cage used) located on the back plane of
the modem rack and the other end into the phone-company-provided RJ11
or RJ11W modular phone jack. Make sure that DIP-Switch #10 is in the UP
position (default) when in dial-up mode.

Although the majority of installations involves dial-up lines, the MT2834
also connects to two-wire leased lines (sometimes referred to as
dedicated, private, or 3002 lines).

To connect the modem to leased lines, first determine the type of line
termination provided by the phone company. Most phone companies
provide a terminal block with a pair of screws. Some provide a
conventional RJ11 type of connector. If the RJ11 connector is used, you
can use the same cable that you use for dial-up connection. If the screw
terminal type connector is used, you may need to order the #CA167 cable
from Multi-Tech Systems.

Make two DIP-Switch setting changes on the modem's PC board. The first
involves placing DIP-Switch #10 in the DOWN position (changes the
modem from dial-up to leased line operation). The second DIP-Switch
change requires that one of the two modems on the leased line circuit is
set to "originate", and the other is set to "answer". To do this, change the
setting of DIP-Switch #5. When you changed the DIP-Switch #10 setting,
you also changed the function of DIP-Switch #5. Now the UP position
selects answer mode frequencies while the DOWN position selects
originate mode frequencies. Place DIP-Switch #5 in the UP position on
one of the two modems, and on the other modem, place Switch #5 DOWN.
It doesn't matter which is which, just so you have local and remote
modems in opposite modes.

16

Chapter 2 - Installation

2.6 Modem LED Indicators

The MT2834 has ten LED diagnostic indicators.

RCV XMT CO 28.8 14.4 24 OH DTR RI ERR

1. Receive Data (RCV). This LED blinks when data is being received, on

for a space, off for a mark. The state of this RCV LED matches that of
the RCV circuit on Pin 3 of the RS232C/V.24 interface.

2. Transmit Data (XMT). 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
XMT circuit on Pin 2 of the RS232C/V.24 interface.

3. Carrier ON (CO). This LED lights when a valid carrier tone has been

detected.

4. 28,800 bps (28.8). This LED is lit when the modem is connected at

28,800 bps.

5. 14,400 bps (14.4). This LED is lit when the modem is connected at

14,400 bps. Note that when both 28.8 and 14.4 LEDs light, modem is in
21,600-26,400 bps mode of operation.

6. 2400 bps (24). This LED is lit when the modem is connected at 2400

bps.

7. Off Hook (OH). This LED is lit when the phone line is “off hook”. This

occurs when the modem is dialing, on line, or answering a call. The
LED also flashes when the modem is pulse dialing in the Command
Mode.

8. Data Terminal Ready (DTR). When the DTR LED is lit, the modem is

permitted to answer an incoming call. When DTR goes off, a connected
modem disconnects if dependent on DTR. The state of this DTR LED
matches that of the DTR circuit on Pin 20 of the RS232C/V.24 interface.

9. Ring Indicator (RI). This LED is lit during the ringing interval as an

incoming call is received.

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Chapter 2 - Installation

10. Error (ERR). When the ERR LED is flashing, the leased line is down

and the modem is in self-test mode has failed. When ERR LED is on,
this indicates the modem is in an out of service (OOS) state. When the
modem is out of service, it is busy to incoming calls.

NOTE: To verify Enhanced V.34 mode is engaged:

1. Type +++AT<CR> .

2. Type ATL8 .

3. The modem's current on-line condition is displayed. An
example of L8 listing is shown below.

Figure 2-2. On-Line Diagnostics

18

Chapter 3 - Installation

Chapter 3 - Configuration

3.1 Introduction

Since your communications software configuration is affected by the
capabilities of your computer, this chapter begins with a discussion of the
limitations of some serial ports and how to identify them. It then discusses
communications configuration in general and recommends settings
specifically for the MT2834.

3.2 Serial Port Limitations

When you configure your software, you need to consider how the hardware
on both ends of the connection will affect the connection. Some serial
ports, particularly those in older PC-compatible computers, may limit the
performance of the MT2834. You should know if yours is one of them.

The limiting factor is an integrated circuit called a Universal Asynchronous
Receiver/Transmitter, or UART. All data from your modem flows through it.
The UARTs typically used in PC-compatible computers are types 8250,
8250A, 16450, and 16550AFN. The 8250 is unreliable above 9,600 bps,
and the 8250A and 16450 are unreliable above 19,200 bps. If the modem
sends data to the UARTs above those speeds, the UARTs may not be able
to process the data fast enough to keep from losing some of it. The
16550AFN, however, can safely handle data to 115,200 bps.

When a modem communicates with V.42bis 4-to-1 compression enabled, it
sends up to four times as much uncompressed data to the serial port as it
receives compressed over the telephone line. Therefore, a modem
communicating at 14,400 bps may require a serial port that can reliably
transfer data at four times 14,400 bps, or 57,600 bps; at 19,200 bps it may
require one that works reliably up to four times 19,200 bps, or 76,800 bps;
and at 28,800 and 33,600 bps it may require one that works reliably up to
a maximum of 115,200 bps. If your serial port cannot handle these speeds,
we recommend that you replace your present serial card with one that has
a 16550AFN UART or equivalent.

Macintosh computers do not use UARTs. The Macintosh SE through IIfx
models use a Zilog Z8530 chip called a Serial Communications Controller,
or SCC, that has a maximum speed of 57,600 bps. This speed can be

20

Chapter 3 - Configuration

compromised by other serial communications, including printer
transmissions and Appletalk, the networking software that allows
Macintoshes to share files. When Appletalk is active it controls all serial
communications on the Macintosh. Because it gives priority to network
communications, it may lose modem data at higher transmission speeds.
Therefore, when Appletalk is active you risk losing data on serial port
communications over 2400 bps, though most users can work up to 9600
bps without problems. Other activities that could cause the serial driver to
drop bits at high speeds include the floppy disk driver formatting a disk, the
CPU paging in or out in virtual memory mode, and the Mac IIci or IIsi
running the on-board video in 8-bit mode. Therefore, for maximum
communications speed on the Macintosh, we recommend as few
concurrent activities as possible. To use V.42bis compression at 19,200
bps or faster, we recommend that you install a high speed serial port card.
Newer Macintosh computers, such as the Quadra and Centris models,
support serial port speeds up to 115,200 bps.

3.2.1 How Can You Identify Your UART Type?

If you have MS-DOS 6.0 or later, you can find your UART type from a
diagnostic program called MSD. To use it, type MSD at the DOS prompt.
After the opening screen, select COM Ports. The last line of the report tells
you what type UART you have for each COM port. MSD does not
distinguish between the 8250 and the 8250A. However, if you have an IBM
AT or newer computer, you likely have an 8250A or 16450 UART installed,
both of which are reliable to 19,200 bps. If you would like more detailed
information about your UART than MSD can provide, you can download
shareware UART identification programs from the IBM Communications
Forum.

21

Chapter 3 - Configuration

Figure 3-1. MSD UART Identification, Screen 1

Figure 3-2. MSD UART Identification, Screen 2

22

Chapter 3 - Configuration

3.3 Configuring Your Software

Communications software must be configured to work with your modem,
your computer, and the remote system it is calling. Fortunately, most
communications programs make the process easy by providing a default
initialization string for your modem as well as defaults for most of the other
required parameters.

3.3.1 Configuring Software for Your Modem

Because remote computers may have different connection requirements
such as speed, number of bits, parity, log-on sequences, etc.,
communications software is typically configured by sessions, each session
having a unique configuration for a given connection (e.g., to a BBS or
commercial online service). Most communications programs, however,
have a separate modem configuration menu because modem
configurations rarely change from session to session.

The most important configuration is the modem initialization string. This is
a sequence of commands the software uses to configure the modem when
the communications software is loaded or when a session begins. Always
begin the initialization string with the ATtention command AT, then follow it
with the modem reset command, &F. Issuing a reset command before
other commands ensures that you are starting with a known state.

The rest of the commands in the initialization string depend on the
capabilities of the modem and what you want it to do. Some older
communications programs require you to create the initialization string by
yourself. Most modern communications programs, however, provide you
with a ready-made initialization string that is automatically selected when
you choose your modem model from a list. It is a poor idea to use an
initialization string intended for another modem, especially one from
another manufacturer, because modem capabilities and command
implementations vary from modem to modem. However, if your MT2834BR
does not appear on a modem list, you may use the MultiModemII
initialization string.

23

Chapter 3 - Configuration

3.4 PC Initialization Strings

We recommend the following initialization string for a MT2834 connected
to a PC-compatible computer:

AT &F X4 S0=0 ^M

This string resets the MT2834 to the factory default settings, selects
extended result codes with NO DIAL TONE and BUSY, and turns off auto­answer. ^M must end every string sent to the modem from software. It is
the ASCII code for the RETURN key on most keyboards, and the default
code for the carriage return character in the MT2834 and most
communications programs. The carriage return character is defined in the
MT2834 in S-register S3; if you change it, you must also change the
carriage return character code used in your communications software. If
you send a command directly to the modem in terminal mode rather than
indirectly through communications software, you must end the command
string by pressing the RETURN key (<CR>) instead of adding ^M to the
string.

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Chapter 3 - Configuration

Figure 3-2. The MEW Modem Initialization Setup

* Note that the above and following set up screens are examples found in

MultiExpress for Windows (MEW), and that other 3rd party data communication
software is similar but different.

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Chapter 3 - Configuration

3.4.1 Changing Default Parameters

The default values for the other parameters in modem configuration menus
rarely need changing. They typically include the dialing prefix (ATDT for
touch-tone service and ATDP for rotary service), the dialing suffix (^M), the
hang-up string (+++ATH0^M), and response messages (RING, NO
CARRIER, BUSY, etc.). Communications software with a host mode might
also include an auto-answer string (AT S0=1^M).

3.5 Macintosh Initialization

Macintosh computers cannot use RTS/CTS hardware flow control without a
serial cable wired for hardware control. The Macintosh 128 and 512
models cannot use RTS/CTS flow control at all. For those Macintoshes
turn off the default RTS/CTS hardware flow control, turn on XON/XOFF
flow control and pacing, and ignore DTR:

AT &F X4 &E5 &E13 &D0 ^M

For hardware flow control, use the following initialization string:

AT &F X4 &E13 &D0 ^M

Add S0=0 to both strings to disable auto-answer if the MT2834BR is on a
voice line.

You can store the initialization string in nonvolatile memory. With your
communications software open and connected to the modem’s COM port,
type the initialization string in the terminal window, substituting a carriage
return for ^M. To store the string, enter

AT &F9 &W0 <CR>.

Now you can initialize your modem with the following simple string:

AT Z ^M

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Chapter 3 - Configuration

3.6 Configuring Software for Your Computer

Configure the communications software to match the computer’s
configuration. If the MT2834 is connected to the COM2 serial port, select
"COM2" under the Device drop-down menu.

Select the appropriate serial port baud rate. This is the speed the modem
communicates with the computer, not the speed the modem communicates
with another modem.

If V.42bis data compression is enabled, select a serial port baud rate four
times the transmission speed of the modem to optimize data compression.
If the UART is fast enough, set the serial port baud rate to a minimum of
four times the top speed of the modem.

Figure 3-3. MEW Configuration Parameters Screen

For an 8250 UART, the most reliable serial port speed is 9600 bps. For an
8250A or a 16450 UART, try 19,200 bps. For a 16550 UART or equivalent,
select a serial port setting of 115,200.

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