Multitech MMH900 User manual

MMH900 Series Statistical
Multiplexer
User Guide

User Guide
S000315A Revision A
MultiMux (#MMH904Ca) (#MMH908Ca)
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 © 2003, 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 Date Description
A 11/01/03 Initial release of MultiMux MMH904/908C for
publication on CD.
TRADEMARK
Trademark of Multi-Tech Systems, Inc. are as follows: MultiMux,
MultiModem and the Multi-Tech logo.
Multi-Tech Systems, Inc.
2205 Woodale Drive
Mounds View, Minnesota 55112
[phone] or [phone]
Fax [phone]
Tech Support [phone]
Internet Address: http://www.multitech.com

Contents
Chapter 1 - Introduction & Description ................................ 8
1.1 Introduction.................................................................................... 9
1.2 About This Manual......................................................................... 9
1.3 Background ................................................................................... 11
1.3.1 Description of Statistical Multiplexing ................................... 12
1.3.1.1 StatisticalMultiplexing .......................................................... 12
1.4 Product Description ....................................................................... 14
1.5 System Features ........................................................................... 17
1.5.1 Response Time Control........................................................ 17
1.5.2 Dynamic Buffering ................................................................ 17
1.5.3 Flow Control ......................................................................... 18
1.5.4 Diagnostics .......................................................................... 18
1.5.5 Downline Parameter Loading ............................................... 18
1.5.6 Operational Statistics andAuto-Reporting............................ 19
1.5.7 Parameter Memory .............................................................. 19
1.5.8 Channel Flexibility ................................................................ 19
1.5.9 Command Modem................................................................ 19
1.5.10 Composite Link .................................................................... 20
1.6 FCC Regulations for Telephone Line Interconnection ................... 21
1.7 DOC Terminal Equipment .............................................................. 23
1.8 Specifications ................................................................................ 24
1.8.1 Channels .............................................................................. 24
1.8.2 System Control..................................................................... 24
1.8.3 Composite LInk .................................................................... 25
1.8.4 33,600 bps Link Modem ....................................................... 25
1.8.5 56,000 bps DSU.................................................................. 25
1.8.6 ISDN TerminalAdapter......................................................... 26
1.8.7 Command Modem................................................................ 26
1.8.8 Electrical/Physical ................................................................ 26
Chapter 2 - Configuration ..................................................... 27
2.1 Introduction.................................................................................... 28
2.2 Configuration 1 .............................................................................. 29
2.3 Configuration 2 .............................................................................. 31
2.4 Configuration 3 .............................................................................. 32

Chapter 3 - Front & Rear Panel Descriptions..................... 34
3.1 Introduction.................................................................................... 35
3.2 Front Panel .................................................................................... 35
3.3 LED Indicators .............................................................................. 36
3.4 Back Panel .................................................................................... 40
3.4.1 ON/OFF Switch .................................................................... 40
3.4.2 Power Connector ................................................................. 40
3.4.3 COMMAND MODEM DIAL-UP Connector .......................... 40
3.4.4 COMMAND PORT Connector .............................................. 40
3.4.5 COMPOSITE LINK INTERNAL MODEM DIAL-UP Connector40
3.4.6 COMPOSITE LINK INTERNAL MODEM LEASED Connector41
3.4.7 COMPOSITE LINK INTERNAL DIGITAL DSU Connector.... 41
3.4.8 COMPOSITE LINK EXTERNAL RS232C/V.35 Connector ... 41
3.4.9 CHANNEL 1 - CHANNEL 8 Connectors............................... 41
3.5 Switches/Jumper/Shunt................................................................. 42
3.5.1 8-Position DIP Switch........................................................... 42
3.5.2 4-Position DIP Switch........................................................... 43
3.5.3 144RKWL/OtherJumper ....................................................... 44
3.5.4 V.24/V.35 Shunt.................................................................... 44
3.5.5 V.29/V.33 Shunt and 2834 Shunt.......................................... 44
Chapter 4- Installation........................................................... 45
4.1 Introduction.................................................................................... 46
4.2 Safety Warnings ............................................................................ 46
4.3 Unpacking...................................................................................... 46
4.4 Installation ..................................................................................... 47
Chapter 5 - Commands ......................................................... 52
5.1 Introduction.................................................................................... 53
5.2 Command Description ................................................................... 58
5.2.1 General Commands ............................................................. 58
5.2.2 Channel Parameter Commands ........................................... 65
5.2.3 Composite Link Commands ................................................. 74
5.2.4 Composite Link Format Commands ..................................... 78
5.2.5 Internal 9600/14.4K Composite Link Modem Commands..... 81
5.2.6 Internal MMH2834 Modem Configuration Commands.......... 84

5.2.7 Internal Composite Link DSU Commands ............................ 86
5.2.8 Test Commands ................................................................... 87
5.2.9 Command Modem commands ............................................. 89
Chapter 6- Operating Procedures ....................................... 90
6.1 Introduction.................................................................................... 91
6.2 MultiMux Operating Procedures .................................................... 91
6.3 Command Modem Operating Procedures ..................................... 95
Chapter 7 - Troubleshooting ................................................ 97
7.1 Introduction.................................................................................... 98
7.2 Importance of Composite Statistics ............................................... 98
7.3 Test Cables.................................................................................... 99
7.4 Troubleshooting Guide .................................................................. 101
7.5 Channel Device Testing ................................................................. 107
7.6 Local Modem and Communications Line Testing .......................... 108
7.7 MultiMux Functional Testing Procedures ....................................... 110
Chapter 8- Service, Warranty, & Technical Support ......... 112
8.1 Introduction.................................................................................... 113
8.2 Warranty ........................................................................................ 113
8.3 Repair Procedures for U.S. and Canadian Customers.................. 114
8.4 Repair Procedures for International Customers (Outside U.S.A. and
Canada) ............................................................................................ 115
8.5 Repair Procedures for International Distributors............................ 116
8.6 Online Warranty Registration......................................................... 116
Appendices.......................................................................... 117
AppendixA .............................................................................................. 118
Ascii Character Code/Hex/Decimal Conversion Chart ...................... 118
Appendix B
RS232C Interface Specification ........................................................ 119

Appendix C.............................................................................................. 121
Cabling Diagrams.............................................................................. 121
Appendix D.............................................................................................. 125
Command Modem Commands ......................................................... 125
Appendix E Command Modem S-Register Function.............................. 138
Appendix F .............................................................................................. 143
Flow Control Background.................................................................. 143
Appendix G ............................................................................................. 146
MMH2834 S-Registers...................................................................... 146
Appendix H.............................................................................................. 149
Dial Back-up...................................................................................... 149
Appendix I ............................................................................................... 150
Testing Your MMH2834 ..................................................................... 150
I.1 Introduction ................................................................................ 150
I.2 LocalAnalog Loopback Test/V.54 Loop 3 .................................. 151
I.3 Digital Loopback Test/V.54 Loop 2 (Loc/Man)...................... 152
I.4 Digital Loopback Test/V.54 Loop (Rem/Auto) ............................ 154
I.5 Synchronous Mode Testing ................................................. 156
I.6 Local Analog Loopback Test (Sync Mode)........................... 157
I.7 Digital Loopback Test (Loc/Man) Sync Mode ...................... 158
I.8 Digital Loopback Test (Rem/Auto)(Sync Mode)................... 159
Appendix J - Internal MMH2834 Composite Link Modem Commands.... 160
J.1.1 DialingAction Commands ........................................................ 163
J.1.2 Dial Modifier Commands ...................................................... 165
J.1.3 Phone Number Memory Commands .................................... 168
J.1.4 Configuration and Default Storage Commands .................... 170
J.1.5 Command Response (Result Code) Commands..................... 172
J.1.6 Phone Line Conditioning Commands ...................................... 176
J.1.7 RS232C Interface Control Commands ..................................... 177
J.1.8 Error Correction Commands ................................................ 178
J.1.9 Compression and Maximum Block Size Commands ............ 180
J.1.10 Speed Conversion Commands............................................. 181
J.1.11 ImmediateAction Commands............................................... 183
Glossary............................................................................... 185
Index..................................................................................... 195

Chapter 1 - Introduction &
Description

8
Chapter 1 - Introduction & Description
1.1 Introduction
Congratulations! Your new MultiMux MMH900 series is one of the finest
statistical multiplexers on the market today. The MultiMux is completely
software driven and is controlled by you through its command port. This
gives you great flexibility and ease of operation. This Owner’s Manual
will help you to install and use your MultiMux, and also provide you with
a valuable information resource in the future.
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Figure 1-1. MultiMux MMH900 Series
1.2 About This Manual
eThis manual is comprised of eight chapters. There are also several
appendices at the end of the manual, most of which is a condensed
version of the information contained in the chapters. These appendices
can be used as a quick reference. The information contained in each
chapter is as follows:
Chapter 1 - Introduction
This chapter is an introduction to the world of multiplexing. Since you
have already acquired the MultiMux, you may have an extensive
background in multiplexing. In which case, this introduction will provide a
good review.
Chapter 2 - Configuration
This chapter defines the configurations of the MMH900 series and
provides some typical examples of how the MultiMux is configured. The
MMH900 series is available in two models; the four and eight channel
units with an internal command modem, various composite link modems
supporting synchronous or asynchronous communications. The typical
examples explain how the MultiMux can be used in various
environments.

9
Chapter 1 - Introduction & Description
Chapter 3 - Front and Rear Panel Descriptions
Chapter 3 describes the front panel indicators, the switches and jumpers
within the cabinet and the rear panel connections. The front panel
indicators are described in the various groups depending on the
configuration of the MultiMux. Indicator groups are active depending on
how the MultiMux is used. The front panel is the same for all models
and contains some indicators for future enhancements. The back panel
provides all the cable connections for the early released models with the
addition of cable connections for future releases.
Chapter 4 - Installation
Chapter 4 provides the procedures for unpacking, installing and cabling
your MultiMux.After your MultiMux is cabled, an initial power on
procedure is provided for you to display and modify the channel and link
parameters to fit your configuration.
Chapter 5 - Commands
The MultiMux is software-driven and controlled through its command port
and the supervisory console. This chapter describes theAT commands
and the impact each has on your system’s operation.
Chapter 6 - Operating Procedures
Chapter 6 provides the operational information for your MultiMux. The
MultiMux operating procedures address the channel and composite link
parameters. The command modem operating procedures address the
command modem access, dialing, and remote access procedures.
Chapter 7 - Troubleshooting Procedures
This chapter is a guide to troubleshooting your MultiMux. It contains a
listing of error conditions, probable causes and suggested fixes or steps
designed to isolate the failing unit in your communications network.
Chapter 8- Service, Warranty and Tech Support
Chapter 8 provides instructions on getting service for the MultiMux at the
factory, a statement of the limited warranty, information about our user
bulletin board service, and space for recording information about your
multiplexer prior to calling Multi-Tech's Technical Support.

10
Chapter 1 - Introduction & Description
1.3 Background
Any data communications environment that has more than one
asynchronous line going between common locations can probably
benefit by installing a pair of statistical multiplexers (stat muxes). A stat
mux performs the function of combining several asynchronous data
communication channels into one composite signal that can be
transmitted between two locations more inexpensively than the cost of
the individual lines.
Figure 1-2 shows a simple communications network. Individual users
connect to asynchronous channels and the composite (or aggregate)
communications line between the two locations is the "link". Link
protocol is the communications discipline used between the two
multiplexers and typically operates at a speed higher than the individual
asynchronous units connected to each multiplexer.
Figure 1-2. Simple Communications Network
One reason that a stat mux works is that typically an asynchronous
terminal device is not used to its capacity. Studies show that as little as
10 to 15% utilization of such lines is a common occurrence. These
percentages indicate that the most efficient combination of lines in a
muxed asynchronous environment is between four and eight lines.
Although the primary reason for installing a mux is to save on
communications costs, two other benefits are also present. One is the
inherent error correction existing in muxed data and the other is data
security. Since a mux functions by taking individual asynchronous data
and transmitting it as data packets, there is an error detection and
retransmission scheme built in. Error correction is so vital in many
transmission types, such as graphic data and program transmission, that
many muxes are used mainly for their error correction capabilities.
The other benefit is data security which is achieved by the fact that the
individual data streams are encrypted into a single communication line