Multi-Tech Systems MT2834ZPX User Manual
Model Number MT2834ZPX
Owner's Manual
Owner’s Manual
82041404 Revision E — 11/25/96
#MT2834ZPX
This publication may not be reproduced, in whole or in part, without prior
expressed written permission from Multi-Tech Systems, Inc.
All rights reserved.
Copyright © 1996, by 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.
Record of Revisions
Revision Description
E Manual revised. This manual documents enhancements
(11/25/96) implemented in firmware version 0.22. Theses enhancements
include extended V.34 rates (33.6K/31.2K); and overall format and
editorial changes throughout this manual.
Trademarks of Multi-Tech Systems, Inc. are as follows: MultiExpress,
MultiExpressFax, MultiModem, MultiModem
II
,
MultiModemµ, Multi-Tech and the Multi-Tech logo.
MNP, Microcom Network Protocol is a trademark of Microcom Inc.
Macintosh is a trademark of Apple Computer Inc.
PC-DOS: International Business Machines Corporation
Pentium: Intel Corporation
AT&T is a trademark of American Telephone and Telegraph Co.
Windows® and Windows® 95 are registered trademarks of Microsoft
Multi-Tech Systems, Inc.
2205 Woodale Drive
Mounds View, Minnesota 55112 U.S.A.
(612) 785-3500 or (800) 328-9717
U. S. FAX 612-785-9874
Fax-Back Service 612-717-5888
Technical Support (800) 972-2439
BBS (612) 785-3702 or (800) 392-2432
Internet Address: http://www.multitech.com
Technical Writer: mark@multitech.com
Contents
Chapter 1 - Introduction and Description
Introduction................................................................................................................ 5
Modem Features ....................................................................................................... 5
Fax Features ............................................................................................................. 6
Product Description................................................................................................... 6
How to Use This Manual........................................................................................... 7
Chapter 2 - Installation and Configuration
Installation ................................................................................................................. 9
Safety Warnings ........................................................................................................ 9
Configuration/Installation Procedure...................................................................... 10
Is Your MT2834ZPX Ready for Use? ..................................................................... 12
Operating Your MT2834ZPX .................................................................................. 13
Simple Operations .................................................................................................. 14
Chapter 3 - Software Configuration
Introduction.............................................................................................................. 15
ConfiguringSoftware for Your Modem............................................................ 15
PC Initialization Strings........................................................................................... 16
Changing Default Parameters ................................................................................ 17
Configuring Software for Your Computer ............................................................... 17
Configuring Software for the Remote System ............................................... 18
Terminal Emulation ......................................................................................... 18
File Transfer Protocols.................................................................................... 19
When to Disable Data Compression ...................................................................... 19
Disabling Error Correction .............................................................................. 20
The 16550 UART and Windows 3.1....................................................................... 20
Chapter 4 - AT Commands, S-Registers and Result Codes
Dialing/On-Line/Answering ..................................................................................... 22
Modem AT Commands ........................................................................................... 23
Remote Configuration..................................................................................... 38
Remote Configuration Procedures................................................................. 38
Password Commands.................................................................................... 39
S-Registers.............................................................................................................. 40
AT Commands and S-Register Summary...................................................... 48
Chapter 5 - Troubleshooting
Troubleshooting.......................................................................................................49
The Modem Does Not Respond to Commands............................................49
The Modem Dials But Cannot Make a Connection.......................................51
The Modem Disconnects While Online..........................................................53
The Modem Cannot Connect When Answering............................................54
File Transfer Is Slower Than It Should Be.....................................................54
Losing Data.....................................................................................................54
Getting Garbage Characters on the Monitor.................................................55
Fax and Communications Software Won’t Run at the Same Time..............55
Chapter 6 - Testing Your Modem
Local Analog Loopback Test/V.54 Loop 3..............................................................56
Digital Loopback Test/V.54 Loop 2 (Local/Manual)...............................................57
Digital Loopback Test/V.54 Loop 2 (Remote/Automatic).......................................58
Chapter 7 - Service, Warranty and Tech Support
Introduction..............................................................................................................60
Limited Warranty.....................................................................................................60
On-line Warranty Registration........................................................................61
Tech Support...........................................................................................................61
Recording Modem Information.......................................................................61
Service.....................................................................................................................62
About the Multi-Tech BBS.......................................................................................63
To log on to the Multi-Tech BBS.....................................................................63
To Download a file..........................................................................................63
About CompuServe/Internet...................................................................................65
About the Multi-Tech Fax-Back Service.................................................................65
Appendix A - Technical Specifications
Appendix B - Tone Dial Frequencies
Appendix C - FCC and Canadian Regulations
FCC Regulations for Telephone Line Interconnection...........................................71
Canadian Limitations Notice...................................................................................74
Index
Chapter 1 - Introduction and Description
Chapter 1 - Introduction and Description
Introduction
Welcome to the world of data communications. You have acquired
one of the finest intelligent data and fax modems available today,
model MT2834ZPX, from Multi-Tech Systems. This Owner’s Manual
will help you install, configure, test and use your MT2834ZPX data/fax
modem.
Modem Features
Your MT2834ZPX modem meets the proposed
standard for data signalling rates as high as 33.6/31.2K bps full-duplex
mode. Connections are made on Public Switched Telephone Networks
(
PSTNs
). V.34 supports and is compatible with all V.32/V.32
V32
terbo
features including EIA extended Automode, adaptive line
probing, automatic symbol rate and carrier frequency during start-up,
and retrain and rate renegotiation (in 2400 bps increments).
Your modem features CCITT V.42 error correction and V.42bis data
compression, providing 100% error-free data transmission. V.42 error
correction incorporates MNP( Classes 3 and 4, and LAP-M. You may
select V.42bis data compression for 4-1 throughput, or MNP Class 5
for 2-1 throughput.)
Your MT2834ZPX offers interactive automatic dialing, as well as
Command Mode option configuration. You may store up to ten
command line/telephone numbers, of up to 60 characters each, in the
modem’s nonvolatile memory. The modem pulse or tone dials, and
recognizes dial tones and busy signals for reliable call-progress
detection. The modem can detect AT&T calling card tones. It is FCCRegistered for connection to telephone networks without any Data
Access Arrangements (DAA’s).
Your modem also features Remote Configuration which permits you to
assist users at remote sites, saving you the time and trouble of site
visits and preventing misinterpretation of configuration instructions.
Enhanced
V.34 ITU
bis
/
5
MT2834ZPX Owner's Manual
Fax Features
Your MT2834ZPX meets the CCITT V.17 standard for sending and
receiving faxes. When linked to a compatible fax machine or modem,
it can transmit faxes at 14.4 K bps. It also meets the CCITT’s Group 3
Designation for sending and receiving faxes at 9600 bps; and Group 2
Designation for sending and receiving faxes at 4800 bps. The
MT2834ZPX is also downward-compatible with modems to speeds as
low as 300 bps, so it can send and receive faxes with any fax machine
in the world.
Product Description
The MT2834ZPX is a internal half-length fax/modem card for IBM
Personal Computers (PC, XT, AT Pentium or compatible units); and
fits into a full- or half-size expansion slot. The MT2834ZPX provides
dial-up asynchronous communication capability with other personal
computers, terminals, on-line computer services or other types of
computer systems. Connection to the phone line is made possible by
an RJ11 modular type connector. The MT2834ZPX can be configured
as either a COM1, COM2, COM3, or COM4 communication port; with
a selection of 5 IRQ values. Selection of a specific COM port/IRQ
value is accomplished by choosing the proper berg jumpers located on
the MT2834ZPX's circuit board. Hardware configuration and
installation procedures are described in Chapter 2.
6
Chapter 1 - Introduction and Description
How to Use This Manual
This manual is divided into seven chapters and two appendices. The
information contained in each chapter and appendix is as follows:
Chapter 1 - Introduction and Description
Chapter 1 begins with a short product introduction and description;
followed by a guide (which you are now reading) to the use of this
manual.
Chapter 2 - Installation and Connection
Chapter 2 documents the procedure for connecting the MT2834ZPX to
your computer and to the phone line. Details are given, supported by
illustrations on determining Base I/O addressing and setting IRQ
values as a guide for installing your MT2834ZPX to the point of
operation.
Chapter 3 - Software Configuration
Chapter 3 documents communication software configuration
recommended specifically for the MT2834ZPX. There is also some
discussion of how to identify the limitations and capabilities of your
computer before the software installation process is done. Some other
issues covered in this chapter include setting up initialization strings,
changing default parameters, configuring software for the remote
system and file transfer protocols.
Chapter 4 - "AT" Commands and S-Registers
This chapter focuses on the use of “AT” commands and S-Registers.
Chapter 4 provides basic steps for originating and answering calls and
a summary of commands that enable the user to establish, read, and
modify parameters in addition to dialing.
Chapter 5 - Troubleshooting Your MT2834ZPX
Chapter 5 lists some basic and specific actions to take if your
MT2834ZPX is not operational.
7
MT2834ZPX Owner's Manual
Chapter 6 - Testing Your Modem
Chapter 6 covers the modem's built-in test features. These are:
Power-on Self Test, Local Analog Loopback, Digital Loopback and
Remote Digital Loopback Tests. We have included a description of
each test and how to use each test procedure.
Chapter 7 - Service, Warranty & Technical
Support/ BBS
Chapter 7 provides instructions for getting modems serviced at the
factory and information on product warranty; information about MultiTech's user Bulletin Board Service (
support via the CompuServe and Internet forums.
BBS
) and receiving technical
Appendices
Appendix A - Technical Specifications
Appendix B - Tone Dial Frequencies
Appendix C - FCC and Canadian Regulations
8
Chapter 2 - Installation and Configuration
Chapter 2 - Installation and Configuration
Installation
This chapter provides you with the procedures to install the Multi-Tech
MT2834ZPX card in your ISA or EISA bus personal computer.
Hardware installation involves:
1) Opening your PC.
2) Setting card configuration (determining COM port
setting and IRQ level).
3) Installing the card into the PC.
Safety Warnings
1. Never install telephone wiring during a lightning storm.
2. Never install telephone jacks in wet locations unless the jack is
specifically designed for wet locations.
3. This product is to be used with UL and
4. Never touch uninsulated telephone wires or terminals unless the
telephone line has been disconnected at the network interface.
5. Use caution when installing or modifying telephone lines.
6. Avoid using a telephone (other than a cordless type) during an
electrical storm. There may be a remote risk of electrical shock
from lightning.
7. Do not use the telephone to report a gas leak in the vicinity of the
leak.
CUL
listed computers.
9
MT2834ZPX Owner's Manual
Configuration/Installation Procedure
Perform the procedures in Table 2-1 to configure and install the
MT2834ZPX card into your ISA or EISA bus host computer.
Table 2-1. Configuration and Installation Procedure
Step Procedure
1 Make sure your computer and any peripheral equipment
connected to it, are turned off. Failure to do so may damage both
your modem and your PC. The card may be installed in any 286-,
386- , 486- or Pentium based computer with an ISA or EISA bus
architecture.
2 Remove the cover of your computer as instructed in your
computer’s documentation.
3 Locate the unused slot(s) which you will be using for your modem
card, and remove the slot cover(s) per the instructions in your
computer’s documentation.
4 Figure 2-1 illustrates the default COM port and IRQ value setting
for this card (COM2/IRQ3). If your application requires an
alternate setting, remove the berg jumpers from the COM2/IRQ3
position and place them in a position that supports your
application. The MT2834ZPX can be configured for either a
COM1, COM2, COM3 or COM4 communication port; with a
selection of five IRQ values for each port. By this means, the user
may select an identical COM port because of the expanded IRQ
value selection option (e.g., the MT2834ZPX has a factory default
of COM2/IRQ3...a Mouse device can also be configured at COM2
but at IRQ4...a Printer device configured at COM2 but at IRQ7...).
10
Chapter 2 - Installation and Configuration
Figure 2-1. MT2834ZPX Printed Circuit Board and Alternate COM
Port/IRQ Settings
11
MT2834ZPX Owner's Manual
Table 2-1 (Cont'd). Configuration and Installation Procedure
Step Procedure
5 Install the MT2834ZPX card into the selected expansion slot(s) in
the same manner as any other add-on card, as instructed in your
computer’s documentation.
6 Fasten the retaining bracket to the computer chassis and replace
the cover.
7 Your MT2834ZPX requires a modular
an RJ11C or RJ11W jack, but could also be an RJ12 or RJ13
jack. To connect the modem to the PSTN line, plug one end of
the RJ11 cable that is provided with the modem into the LINE
JACK connector and the other end into the phone-companyprovided RJ11C or RJ11W modular phone jack.
If you wish to have a telephone set connected to the same
telephone line for voice communications, you may plug a
telephone set into the modem's connector labeled
This connector is provided as a convenience. Simply plug one
end of the RJ11C's modular jack that is provided with the modem
into the modem's
the telephone's RJ11C's connector. Note: Any cables connected
to the computer must be shielded to reduce interference.
8 Turn power on to your computer.
PHONE JACK
LINE JACK
. This is typically
PHONE JACK
connector and the other end into
.
Is Your MT2834ZPX Ready for Use?
As soon as you connected power to the modem, if you’re an
experienced modem user, you may simply want to check your
modem’s settings for data compression, error correction, and so on.
You may find that you can get moving quite quickly if you just issue an
ATL5, ATL6
your modem is currently configured. If you come across a setting
you’re unsure of, refer to Chapters 3 and 4 of this manual for AT
command and S-Register explanations and defaults.
If you’re a novice, please continue to the next sections of this chapter.
12
and an
ATL7
command. These commands lists how
Chapter 2 - Installation and Configuration
Operating Your MT2834ZPX
You control your MT2834ZPX by issuing AT commands and setting SRegisters. Right now your MT2834ZPX is set up for the most typical
user application, that is, as a traditional modem set to make a dial-up
call to a remote installation where the call is answered automatically;
therefore, you shouldn’t need to change the current default
configuration. (If however, you know that your application does not
follow this profile, please refer to Chapters 3 and 4 for AT Commands
and S-Registers.)
In operating your MT2834ZPX it is likely that you will use your data
communications software to either:
• enter “terminal” mode, where you can “speak most directly” to the
modem by issuing AT commands, or to
• launch a datacomm session through a set of modem
configurations which you select and then associate with a target
telephone number. Once you have created, saved, and named
this set of information according to your connection needs and
your datacomm software’s conventions, the software then
simplifies your dialing because you needn’t reconfigure your
modem, nor run the risk of mistakenly keying-in incorrect
information.
Either way, you need to understand that an AT command is the
method by which your modem is controlled, and must therefore prefix
nearly all commands. AT stands for attention, and alerts the modem
that a command follows. You may enter these commands with either
upper- or lower-case characters. Entering AT automatically sets the
modem’s serial baud rate to match your computer’s and also sets the
modem’s parity. It also clears the modem’s command buffer.
Once you’re in terminal mode, enter AT followed by <CR> to check
whether your modem is operational. If everything’s fine, your modem
will respond OK.
13
MT2834ZPX Owner's Manual
Simple Operations
You can dial a number by using the ATD command and the phone
number of the modem with which you wish to connect, e.g.,
ATD6127853500. Your modem will dial the number; a “scrambling”
noise is heard as the modem negotiates the kind of connection it can
make, and once the modems have settled on a common connection, a
connect message on your computer’s video is displayed.
To hang up a call, enter +++ATH<CR>. Your modem will return on
hook, just as if you had returned a phone’s handset to its cradle. Your
video now displays OK, signifying that your modem is ready for your
next command.
14
Chapter 3 - Software Configuration
Chapter 3 - Software Configuration
Introduction
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
defaults for most of the other required parameters.
initialization string
for your modem as well as
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
each session having a unique configuration for a given connection
(e.g., to a BBS or commercial on-line service). Most communications
programs, however, have a separate modem configuration menu
because modem configurations rarely change from session to session.
sessions
,
The most important configuration is the modem
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 MT2834ZPX does not appear on a modem
list, you may use the MultiModemII initialization string.
initialization string.
15
MT2834ZPX Owner's Manual
PC Initialization Strings
We recommend the following initialization string for a MT2834ZPX
connected to a PC-compatible computer:
AT &F X4 S0= 2 ^M
This string resets the MT2834ZPX to the factory default settings,
selects extended result codes with
turns on auto-answer to answer on the second ring. ^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 MT2834ZPX and most
communications programs. The carriage return character is defined in
the MT2834ZPX 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.
NO DIAL TONE
and
BUSY,
and
Figure 3-1. The MEW Modem Initialization Setup
*Note that the above and following setup screens are examples found in
MultiExpress for Windows (
software is similar but different.
16
MEW
), and that other 3rd party data communication
Chapter 3 - Software Configuration
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 (
software with a host mode might also include an auto-answer string
(AT S0=1^M).
RING, NO CARRIER, BUSY,
etc.). Communications
Configuring Software for Your Computer
You must configure your communications software to match your
computer’s configuration. If the MT2834ZPX is connected to the
COM2 communications port, you must tell the software you are using
COM2. Another important parameter is the serial port baud rate. This
is the speed at which your modem communicates with your computer,
not
the speed at which your modem communicates with another
modem. When V.42bis data compression is enabled, you must have a
serial port baud rate four times the transmission speed of the modem
to optimize making data compression effective.
Figure 3-2. MEW Configuration Parameters Screen
17
MT2834ZPX Owner's Manual
Configuring Software for the Remote System
You must meet the requirements of the remote system for successful
communications. Though the MT2834ZPX can automatically match
the speed of the other modem, you must specify parameters such as
type of flow control, break length, number of data bits, number of stop
bits, and parity. If you set these parameters incorrectly with the remote
system, gibberish will appear on your screen (See Figure 3-2).
Terminal Emulation
If you are accessing the remote computer as if from an on-site
terminal, the keyboard codes used by your computer may not match
the ones used by the remote computer. To be compatible with the
remote computer, your software must be able to substitute the
appropriate codes in what is known as
communications programs can emulate the most common mainframe
terminals, including the DEC VT100, VT102, and VT52 terminals, and
the basic TTY mode. If in doubt about which to choose for a BBS, try
ANSI or VT100 first. The following is the MultiExpress for Windows
Terminal Emulation selection screen:
terminal emulation
. Most
18
Figure 3-3. MEW Terminal Emulation Setup Screen
Chapter 3 - Software Configuration
File Transfer Protocols
When you upload or download files with your modem, the host
computer will ask which file transfer protocol you want to use. Most
communications programs allow you to choose a default protocol.
Your software’s documentation should list the ones it can use (not all
communications programs support all protocols). Zmodem is the
default protocol in
most transfers. The following is the
screen:
Figure 3-4. MEW File Transfer Protocols Screen
MultiExpress for Windows
MEW
File Transfer Protocols
, and we recommend it for
When to Disable Data Compression
The speed advantage hardware compression gives you is entirely
dependent on how much the data being transmitted can be
compressed. If the data is already in compressed form—a .ZIP or a
.SIT file, for example—trying to compress it more will actually slow the
transmission slightly compared to transmitting the same file with
compression disabled. This effect will be most noticeable if your
modem negotiates MNP 5 compression with the other modem. V.42bis
will not try to further compress a compressed file, but MNP 5 will.
The command to disable compression is AT &E14 <CR>. If you use
your modem mostly for downloading long, compressed files from
BBSs, you may want to include the &E14 command in your
initialization string as follows:
AT &F S0=0 X4 &E14 ^M
19
MT2834ZPX Owner's Manual
As a general rule, you should try to transmit files in alreadycompressed form rather than relying on V.42bis hardware
compression. Because software compression is more efficient than
hardware compression, you will have a higher throughput with the
former. Of course, this efficiency does not include the time spent
compressing and decompressing .ZIP or .SIT files, but it will save on
phone bills. And hardware compression will still be there for those
occasions when it is inconvenient to compress a file with software.
Disabling Error Correction
By default, the MT2834ZPX is set to auto-reliable mode. In this mode
the MT2834ZPX determines during the handshake whether the other
modem is using V.42 error correction. If it is, the MT2834ZPX then
switches itself to reliable mode and enables error correction. If it is not,
the MT2834ZPX remains in non-error correction mode.
Typically, we recommend that you leave the MT2834ZPX set to autoreliable mode (&E1). However, you may encounter some
circumstances in which the MT2834ZPX will work better with error
correction turned off. For example, it has been reported that on
CompuServe error correction will slow file transfers at modem speeds
of 9600 bps and under. If this is a problem for you, you can turn off
error correction with the command AT &E0, or you can include the
command in your initialization string as follows:
AT &F S0=0 X4 &E0 ^M
The 16550 UART and Windows 3.1
Windows 3.1 may cause a loss of data when communicating at high
speed, even with a 16550 UART installed. Because Windows is
multitasking—it switches between several programs running at the
same time—it can make the serial port wait briefly while Windows
performs other tasks. Meanwhile, incoming data can be lost. The older
8250A and 16450 UARTs can store data in a one-byte first in-first out
(FIFO) buffer (a memory area in the UART in which the first bit in is
the first out), but once the buffer is full, the data is lost. The 16550 has
a 16-byte FIFO buffer, which accounts for much of its high speed.
However, in Windows 3.1, the 16550’s FIFO buffer is disabled by
default.
20
Chapter 3 - Software Configuration
To enable the buffer, use Notepad to open the SYSTEM.INI file in your
Windows directory, and add the following line to the [386Enh] section:
COMnFIFO=1
where n is the number of the COM port the 16550 is installed on. For
example, if the 16550 is installed on COM2, the line should be:
COM2FIFO=1
After you save SYSTEM.INI you must restart Windows for the change
to take effect.
However, there is another problem when the FIFO buffer is enabled:
Windows cannot recognize the COM port because of a bug in the
Windows 3.1 serial port driver, COMM.DRV. The only way around this
problem is to replace the COMM.DRV file in the WINDOWS\SYSTEM
directory with another driver. Several drivers are available
commercially or on BBSs that will solve this problem. A freeware driver
called CyberCom is available as CYBERC.ZIP on CompuServe in the
IBM Communications Forum, Library 0. CyberCom will enable
Windows communications at speeds up to 115,200 bps if you have a
16550 UART installed.
21
MT2834ZPX Owner's Manual
Chapter 4 - AT Commands, S-Registers and Result
Codes
Dialing/On-Line/Answering
There are several basic steps for
communication mode:
1. Load communication software
2. Dial
3. Establish On-Line connection
4. Terminate Call
A simple way to dial is from the keyboard of your computer or terminal.
You enter a command on the keyboard to tell the MT2834ZPX to dial.
If you use a sophisticated communications software package
(e.g., MultiExpress for Windows), the software tells you to enter phone
numbers and other information. If this is the case, the software, and
not you, gives the dialing commands to the modem. All of the
commands, S-Registers and intelligent features of the MT2834ZPX is
taken care of by the software.
If you are giving commands directly to your modem (and not through
your software), each command must begin with AT (ATtention
Characters). AT characters may be entered in upper or lower case.
Entering AT automatically sets the modem’s speed to match the speed
of the computer or terminal, and also sets the modem’s parity. If you
are using a terminal, you can issue commands directly, but computers
must be placed in terminal mode before the modem recognizes
commands. To operate the computer in terminal mode, you must run
a data comm package like MultiExpress, or MultiExpress for Windows,
depending on the type of datacomm call you want to place and
whether you are calling under a DOS or Windows environment. Refer
to your software's documentation to load and run the datacomm
software.
“originating”
and
“answering”
in data
AT characters alert the modem that a command follows. The AT
Command can also be used to clear the command buffer, by simply
typing AT and hitting RETURN.
The letter D in a command causes the modem to dial the numbers
immediately following it (e.g., ATD6127853500).
22
Chapter 4 - AT Commands, S-Registers and Result Codes
The MT2834ZPX responds with
after the number is dialed and a connection signal is detected (since
the MT2834ZPX defaults to Enhanced V.34/V.42/V.42
response is "
in
“On-Line”
If no connection signal is detected within 45 seconds (this time period
can be adjusted by S-Register S7), the MT2834ZPX goes On Hook/
hangs up and returns to Command mode. At this point, your video
displays “
Enter +++ATH<CR> to Hang Up On-Line (bring modem on-hook), and
terminate the modem's On-Line mode. At this point, your video
displays “OK”.
In addition to the call originating capabilities, the MT2834ZPX can also
automatically answer incoming calls. You need not be present. You
can, however, control the situation by configuring the modem to either
answer or not to answer, or to answer after a specified number of
rings. This is done by setting the value of S-Register S0 (modem
defaults to automatically answer an incoming call after one ring).
CONNECT LAPM COMPRESSED
mode, and is ready to communicate with a host site.
NO CARRIER
”.
“CONNECT”
on your video display
bis
, the actual
”). The modem is now
Modem AT Commands
AT commands are the means by which you, and your communications
software, are able to communicate with and configure your modem.
They enable you to establish, read, and modify parameters in addition
to dialing. The following provides a summary and brief explanation of
the AT commands recognized by the MT2834ZPX.
COMMAND: AT
VALUES: n/a
DEFAULT: n/a
DESCRIPTION:
Attention Code that precedes most command
strings except A/, A: and Escape Codes.
COMMAND: Return
VALUES: n/a
DEFAULT: n/a
DESCRIPTION:
Pressing RETURN key executes most commands.
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MT2834ZPX Owner's Manual
COMMAND: A
VALUES: n/a
DEFAULT: n/a
DESCRIPTION:
Answer call, even if no ring present.
COMMAND: A/
VALUES: n/a
DEFAULT: n/a
DESCRIPTION:
Repeat last command. (Do not precede this
command with AT. Do not hit RETURN to
execute.)
COMMAND: A:
VALUES: n/a
DEFAULT: n/a
DESCRIPTION:
Continuous redial (10 redials in DOC units) of
last number until answered.
(Not used in International Models.)
COMMAND: $
VALUES: n/a
DEFAULT: n/a
DESCRIPTION:
This symbol placed in dialing string enables
the modem to detect AT&T's "call card"
tones to access user's calling card when
originating an on-line connection--
COMMAND: $A
n
VALUES: n = 0 or 1
DEFAULT: $A0
DESCRIPTION:
$A0 discards data during auto-reliable time
period.
$A1 buffers data during auto-reliable time
period.
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Chapter 4 - AT Commands, S-Registers and Result Codes
COMMAND: #A
n
VALUES: n = 0 thru 3
DEFAULT: #A0
DESCRIPTION:
#A0 selects initial handshake at 33,600 to 31,200 to 28,800
to 24000 to 21,600 to 19,200 to 16,800 to 14,400 to12,000
to9600 to 4800 to 2400 to 1200 to 300 bps.
#A1 selects initial handshake at 33,600 bps only.
#A2 selects initial handshake at 33,600 to 31,200 to 28,800
to 24000 to 21600 to 19,200 to 16,800 19,200 to 14,400
to 9600 to 4800 bps.
#A3 selects initial handshake at 2400 to 1200 to 300 bps.
COMMAND: &B
n
VALUES: n = 0 or 1
DEFAULT: &B0
DESCRIPTION:
&B0 selects normal transmit buffer size.
&B1 selects reduced transmit buffer size.
COMMAND: &BS
n
VALUES: n = 0 or 1
DEFAULT: &BS1
DESCRIPTION:
&BS0 selects maximum transmit block size of 64 characters.
&BS1 selects maximum transmit block size of 256
characters (MNP mode)/128 characters (LAP-M mode).
COMMAND: B
n
VALUES: n = 0 or 1
DEFAULT: B0
DESCRIPTION:
B0 selects V.21 for 300 bps operation.
B1 selects for 300 bps operation.
(Not used in International Models.)
COMMAND: $BA
n
VALUES: n = 0 or 1
DEFAULT: $BA0
DESCRIPTION:
$BA0 selects speed conversion on.
$BA1 selects speed conversion off.
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