Multitech MMH900, MMH904Ca, MMH908Ca 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
(763) 785-3500 or (800) 328-9717
Fax (763) 785-9874
Tech Support (800) 972-2439
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 Statistical Multiplexing .......................................................... 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 and Auto-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 T erminal Adapter......................................................... 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
Appendix A .............................................................................................. 1 18
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
T esting Your MMH2834 ..................................................................... 150
I.1 Introduction ................................................................................ 150
I.2 Local Analog 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 Dialing Action 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
Immediate Action Commands............................................... 183
Glossary............................................................................... 185
Index..................................................................................... 195
Chapter 1 - Introduction &
Description
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.
A
Command Modem
RCV
CD
External Composite Link
CD
RCV
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BUFFER
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FULLNESS
T
LEVEL
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XMTRCV XMTRCV XMTRCV
RCV
XMTRCV
Channel Eight
RCV XMTXMTRCV
Channel Six Channel Seven
Channel Five
XMT
OH
RCV
XMT
DTR
Channel one
V.35
Channel Two Channel Three Channel Four
XMT
CTS
XMT
M
IT
2
1
3
Internal Composite Link
ISDN
MMH2834 CD RCV XMT CTS 28.8 24.0 19.2 14.4 OH TR EC DBUP
DSU CD RCV XMT CTS 56 19.2 RTS NS OOS TM
V29/V33 CD RCV XMT CTS
INTERNAL LINK DEVICE
F
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(Modems)
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MultiTech
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Systems
MultiMux
Statistical Multiplexer
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.
8
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 the AT 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.
9
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
10
Chapter 1 - Introduction & Description
on one end of the link and then broken up into individual components on
the other end. Someone wishing to "tap" into a muxed signal must not
only have the link protocol which is typically a proprietary version of High
Level Data Link Control (HDLC), but must also know the individual
channel assignment schemes and data formats.
1.3.1 Description of Statistical Multiplexing
A statistical multiplexer (also known as a stat mux) is a device that
allows several other devices (usually computer terminals or PCs) to
communicate over a single transmission line. Sometimes called
concentrators, they take data from different devices and combine it into a
single stream that can be transmitted, via a modem, to an identical
multiplexer at another location, where the stream is then separated back
into its original form. Physically , a mux looks like a box with a bunch of
serial ports and some LEDs. The most typical task of the MultiMux is to
connect a group of PCs or terminals at one site to a mini or mainframe
computer at another site via a single set of modems rather than using
individual modems for each PC or terminal.
1.3.1.1 Statistical Multiplexing
Statistical multiplexing is sometimes referred to as statistical timedivision multiplexing (STDM). The use of the voice-grade phone line (or
any other communications link) is based not on peak data rates, but on
effective (or average) data rates.
During the peaks, when the sum of the data rates of the channels being
served exceeds the data rate of the composite link, a statistical
multiplexer saves the excess data in buffers (in effect, allowing individual
channel buffers to expand). The buffers are emptied as soon as the
activity falls off. The proper allocation of buffer space, plus the
implementation of “flow control” and “pacing” techniques to
accommodate unusually high peaks, allows the use of composite link
speeds that are less than the sum of the individual channel speeds.
In effect, a statistical multiplexer services only active channels. However ,
the efficiency thus realized is not the only benefit of the technique.
Because composite link activity need not be synchronized with the
activity on the individual channels, there is considerable flexibility in the
choice of the composite channel protocol and speed. The use of a
synchronous protocol like HDLC provides for error detection and
retransmission over the composite link. Thus, asynchronous terminals,
which have no inherent error-recovery capability , can enjoy end-to-end
data integrity.
11
Chapter 1 - Introduction & Description
1.3.1.2 Communications
The basic functions of multiplexing are to make communications more
efficient, to provide a means of improving accuracy of asynchronous
communications by using synchronous techniques, and to improve data
security by encrypting several data streams into one coded link.
The channel devices can be any asynchronous RS232 compatible units,
from “dumb terminals” to personal computers running asynchronous
communications software. The connection between the channel devices
and the MultiMux is made through an RS232 interface cable.
Asynchronous modems (long haul or short haul), asynchronous modem
emulators and asynchronous line drivers (DCE devices) can be used in
this connection (up to 38.4K bps) to extend the distance between the
channel devices and the MultiMux.
The connection between the two MultiMuxes is the composite link, and
can be up to 128K bps. Using an internal modem, ISDN terminal
adapter, DSU, or external device, the MultiMux can be connected to
different types of communications links, such as a dial-up line, leased
line, Basic Rate Interface (BRI) ISDN service, or a DDS network. If an
external link device is used the MultiMux can communicate with it using
either the RS232 or V.35 standard.
12
Chapter 1 - Introduction & Description
Workstation PC
1.4 Product Description
There are two basic models of MultiMux MMH900 series available: a
four channel and eight channel units with internal command modem,
optional composite link modems and a command port. The four channel
MultiMux MMH904 connects four async devices to asynchronous
channels that transfer data at a channel speed of up to 38.4K bits per
second (bps). The eight channel MultiMux MMH908 connects eight
async devices. The composite link of the MultiMux MMH900 series can
be configured for various dial-up and lease line modems, a Digital
Service Unit (DSU) for digital communications over a Digital Data
Service (DDS) or dedicated network, or an ISDN terminal adapter for
Basic Rate Interface Service. The command port allows you to
configure the MultiMux MMH900 series for your channel configuration,
internal hardware and composite link configuration.
A simplified block diagram of a MultiMux network is shown in Figure 1-3
to give you a pictorial view of a complete network. The MultiMux
represented in the figure is a MultiMux MMH904 connected to four async
devices on CHANNEL 1 through CHANNEL 4. The workstation
connected to the COMMAND PORT is the supervisory console in which
you can communicate with the command processor or command
modem. If a remote connection is needed to the command modem, a
separate DIAL-UP connection is provided. The composite link can be
configured for an internal 28.8K bps dial-up/leased line modem, internal
DSU for digital communications over a digital data service (DDS)
network or an ISDN terminal adapter for Basic Rate Interface Service. It
can also be configured for external synchronous link device with either
V.24 or V .35 interface.
Figure 1-3. MultiMux MMH900 Series Block Diagram
To setup a MultiMux MMH900 series, the async devices have to be
connected to the channels, the composite link connected to the public
data network (PDN) and the MultiMux has to be configured for the
Channel
Channel
Channel
Channel
Command
Port
4
3
2
1
Data
I/O
Processor
AT Commands
Channel
Data
Channel
Data
Command
Processor
I/O
ATCommands
MultiMux 900 Series
Composite
Link Data
AT Commands
Command
Modem
Dial-Up Modem
Lease Modem
DSU
AT Commands
C
o
m L
p i
o n
s k
i
t
e
Dial-up
Dial-Up Modem
Lease Modem
Digital
Dial-up
Composite
Link
Line
PDN
Dial-up
Composite
Link
PDN
Line
Workstation PC
13
Chapter 1 - Introduction & Description
channel devices and the composite link. The async devices are
connected to CHANNEL 1 through CHANNEL 4 connectors on the back
panel of the MultiMux MMH904 with an RS232 cable. The MultiMux
MMH908 has four additional channel connectors for connecting up to
eight devices.
A number of internal and external composite link devices can be used to
connect the MultiMux to the PDN. The MMH900 series has an internal
28,800 bps composite link modem or an internal 56,000 bps DSU. The
modem is connected to the PDN through the INTERNAL COMPOSITE
LINK LEASED MODEM connector on the back panel of the MultiMux.
The internal DSU is connected to a DDS or dedicated network through
the COMPOSITE LINK DIGIT AL DSU connector on the back panel.
The supervisory console is connected to the MultiMux through the
COMMAND PORT connector on the back panel. The supervisory
console connection is also an RS232 connection. This completes a
typical hardware setup for a MultiMux. Now the MultiMux has to be
configured to talk to the channel devices and communicate over the
composite link.
Configuration of a MultiMux is accomplished through a combination of
setting DIP switches behind the front panel and software commands
entered through the supervisory console. The DIP switches determine
whether the MultiMux is a four or eight channel multiplexer, whether the
composite link device is an internal modem or DSU or an external
device, whether or not the command modem will accept remote access,
etc. The DIP switches control the hardware setup and the operating
setup is controlled through software commands. The software
commands are entered at a terminal connected to the COMMAND
PORT which are transferred to either the command processor or
command modem in the MultiMux. The software commands are AT
commands that configure the channel devices to communicate with the
MultiMux and configure the composite link device to communicate with
the PDN. To configure a channel device, the correct channel speed has
to be established, number of data and stop bits in a word determined,
the type of flow control and whether or not it is used and whether or not
pacing is active. These are just some of the AT commands that are used
to configure and display the status of the channel devices.
When the MultiMux MMH900 series is powered up, the command
processor transfers the stored configuration of the channel devices to
the data processor. The data processor takes the configuration
information and configures each channel for its particular conditions.
14
Chapter 1 - Introduction & Description
The composite link has to be configured for its parameters before data
can be transferred.
The composite link parameters are determined by more than just AT
commands transferred to the command processor. The composite link
parameters are determined by what type of device is used, whether it is
internal or external, speed, what type of remote multiplexer we are
communicating with and a number of line conditioning parameters. The
type of device used as the composite link device is determined by
whether the device is internal or external which is established by a DIP
switch setting and by the type of device installed in the MultiMux or
connected to the EXTERNAL COMPOSITE LINK RS232C/V.35
connector on the back panel. If an internal composite link MMH2834
modem is installed, the DIP switch would be set for an internal
composite link device. The type of MultiMux at the other end of the
composite link is determined by the setting of a four position DIP switch
within the MultiMux. The MultiMux MMH900 series is now ready to
transfer data from its async devices through an internal composite link
modem.
15
Chapter 1 - Introduction & Description
1.5 System Features
1.5.1 Response Time Control
Response time control is the technique used by a mux to make sure that
no user experiences undue delays in performance due to a specific
channel using too much link time. This can occur if one of the channels
is performing a high volume batch function, such as a print dump or
program transfer.
There are a variety of priority control (response time) schemes in use by
different mux vendors. Some vendors use a switch selection approach
where each channel can be given a high, medium or low setting with the
low used for those channels requiring higher volume batch transfers.
There are also software-sensing response time techniques where the
microprocessor actually monitors channel activity , and when a high
volume is sensed, that channel is given a lower priority so it will not
crowd out the others.
The MultiMux response time control method is one where data is
transferred from each channel on a timed basis while limiting the amount
sent with each transmission.
This insures that interactive users will not experience undue delays but,
on the other hand, batch activity can still be accommodated. This,
combined with a Response Time command and the ability to shut of f
channels not being used, gives the MultiMux a very efficient priority
control system.
1.5.2 Dynamic Buffering
A basic requirement of all muxes is some sort of buf fering capability to
temporarily hold channel data while it is being assembled into a block. In
the early days, a mux was sometimes judged by the size of its buffers.
Large buffers are unnecessary in newer designs that include
sophisticated dynamic buffer allocation techniques where the amount of
buffer per channel is assigned on an as-needed basis.
In the MultiMux, each channel is assigned 1K of buffer, but in the case
where more buffer is needed, the MultiMux will start assigning additional
buffers from the channels not requiring it. In this way a single channel
can have up to 8K of buffer if required. When dynamic buffering is
combined with efficient flow control and the automatic transmission of
data from each channel at set intervals, as in the MultiMux, very smooth
operation for each user is the result.
16
Chapter 1 - Introduction & Description
1.5.3 Flow Control
Flow control regulates the volume of data entering the buffers. When a
particular channel buffer is almost full, a flow control command is issued
which stops further activity until the buffer is emptied. The most common
flow control methods currently used are Xon/Xoff, RS232C signal control
(using DTR or CTS) and ENQ/ACK. The MultiMux supports all three.
MUX INITIATED
FLOW CONTROL
Channel
Device
Flow control stops the
input of data to the mux
DATA
Mux
CHANNEL DEVICE
INITIATED PACING
DATA
Mux
Pacing stops the output
of data from the mux
Channel
Device
1.5.4 Diagnostics
Diagnostics in a multiplexer network are of considerable importance.
When a multiplexer fails there is not just one operator down, but many .
That is why the MultiMux is equipped with several diagnostic modes that
will test every aspect of the network. The diagnostics include easy-toexecute tests for each channel, the composite link and for various
components of the MultiMux unit itself. There are nine different test
modes to ensure error free operation. They include Analog Loop, Digital
Loop, Remote Analog Loop, Switch and LED tests, Non-Volatile Memory
test, three other tests and a “Watchdog Timer” reset test.
1.5.5 Downline Parameter Loading
Operational parameters for both local and remote MultiMux units can be
set from one location. The MMH900 series can downline load
parameters to each other, but they cannot send parameters to the
MM16xx/MM32xx and MMH16/MMH32 units. When power is first applied
(or a Reset command is executed) to the local or remote MultiMux,
operational parameters are automatically sent over the composite link to
the remote MultiMux. For this function to work, the 8-position DIP switch
SW1 on the local (sending) MultiMux must be set to the OPEN position
and on the remote (receiving) MultiMux the 8-position DIP switch SW1
must be set to the CLOSED position.
17
Chapter 1 - Introduction & Description
1.5.6 Operational Statistics and AutoReporting
Operational statistics provides the activity report for the MultiMux
network, and Auto-Reporting provides a means to report on these
statistics through the supervisory console on a set periodic time cycle.
Statistics such as receive-block errors pinpoint modem or line problems,
and flow control time totals indicate channel devices being set at
excessive speeds. T wo simple commands are all that is necessary to
select statistical reporting and time cycle. If your command port is also
connected to a printer, the reports can provide an easy means of
generating data for better network management.
1.5.7 Parameter Memory
A nonvolatile memory for storing configurations and options means that
the MultiMux remains configured until you change it. Using this feature,
you can configure a MultiMux, turn it off, ship it and use it without having
to reconfigure it.
1.5.8 Channel Flexibility
The MultiMux permits a great deal of flexibility in configuring channel
parameters. You can mix up channel options, including speed, word
length, stop bits, parity , flow control, pacing methods, echoes and passthrough characters. Channel control commands let you change single
channels, all channels or selected channels with a single command. By
using the downline loading capability or the command modem, channels
can be configured at the other end of the network.
1.5.9 Command Modem
The MultiMux can connect to a dial-up phone network through an
integral 2400/1200/300 bps V .22bis-compatible modem called the
“command modem”. The command modem is an asynchronous modem
used for remote configuration of the mux. The command modem is not to
be confused with the “link modem”, which is either an internal or external
synchronous or external asynchronous device handling the data
transfers over the composite link between two muxes.
By using the command modem, you get the equivalent of a remote
Command Port console. Your MultiMux can be dialed into from a remote
location for remote testing and configuration. The command modem will
automatically answer incoming calls.
18
Chapter 1 - Introduction & Description
1.5.10 Composite Link
The composite link of the MultiMux is capable of synchronous,
asynchronous and digital communications. The MultiMux can be
connected to several different types of communications links through
various modems and DSUs connected internally and externally .
Internally the MultiMux can be configured with synchronous lease line
modem at a link speed up to 28.8K bps or a Data Service Unit (DSU) at
link speeds up to 56K bps. Externally the MultiMux can be configured
with either a synchronous or asynchronous composite link modem or a
DSU for digital communications. The external modems must have error
correction and should have data compression for increased thru put and
only hardware flow control.
19
Chapter 1 - Introduction & Description
1.6 FCC Regulations for Telephone Line
Interconnection
1. This equipment complies with Part 68 of the FCC rules. On the
outside surface of this equipment is a label that contains, among
other information, the FCC registration number and ringer
equivalence number (REN). If requested, this information must be
provided to the telephone company .
2. As indicated below the suitable jack (USOC connecting
arrangement) for this equipment is shown. If applicable, the facility
interface codes (FIC) and service order codes (SOC) are shown.
3. The ringer equivalence number (REN) is used to determine the
quality of devices which may be connected to the telephone line.
Excessive REN’s on the telephone line may result in the devices not
ringing in response to an incoming call. In most, but not all areas, the
sum of the REN’s should not exceed five (5.0). To be certain of the
number of devices that may be connected to the line, as determined
by the total REN’s, contact the telephone company to determine the
maximum REN for the calling area.
4. If this equipment causes harm to the telephone network, the
telephone company will notify you in advance. But if advance notice
isn’t practical, the telephone company will notify the customer as
soon as possible. Also, you will be advised of your right to file a
complaint with the FCC if you believe it is necessary .
5. The telephone company may make changes in its facilities,
equipment, operations, or procedures that could affect the operation
of the equipment. If this happens, the telephone company will
provide advance notice in order for you to make necessary
modifications in order to maintain uninterrupted service.
6. If trouble is experienced with this equipment (the model of which is
indicated below) please contact Multi-Tech Systems, Inc. at the
address shown below for details of how to have repairs made. If the
trouble is causing harm to the telephone network, the telephone
company may request you remove the equipment from the network
until the problem is resolved.
7. 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 .
20
Chapter 1 - Introduction & Description
8. This equipment cannot be used on public coin service provided by
the telephone company. Connection to Party Line Service is subject
to state tariffs. (Contact the state public utility commission, public
service commission or corporation commission for information.)
9. If required, this equipment is hearing aid compatible.
Manufacturer: Multi-Tech Systems, Inc.
Model Number: #MMH904/MMH908
FCC Registration No.: AU7USA-73205-FA-E
AU7USA-18883-DE-N (DSU)
Ringer Equivalence: 0.8B (command modem)
Modular Jack (USOC): RJ11C or RJ1 1W (single line)
Service Center in USA: Multi-Tech Systems, Inc.
2205 Woodale Drive
Mounds View , MN. 55112 USA
(763) 786-3500 or (800) 328-9717
U.S. FAX (763) 785-9874
21
Chapter 1 - Introduction & Description
1.7 DOC Terminal Equipment
Notice: The Canadian Department of Communications label identifies
certificated equipment. This certification means that the equipment
meets certain telecommunications network protective, operational and
safety requirements. The department does not guarantee the equipment
will operate to 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. In some cases, the
company’s inside wiring associated with a single line individual service
may be extended by means of a certified connector assembly (telephone
extension cord). 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 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 insure 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.
The Load Number (LN) assigned to each terminal device denotes the
percentage of the total load to be connected to a telephone loop which is
used by the device, to prevent overloading. The termination on a loop
may consist of any combinations of devices subject only to the
requirement that the total of the Load Numbers of all the devices does
not exceed 100.
The load number for the Command Modem is 8.
22
Chapter 1 - Introduction & Description
1.8 Specifications
1.8.1 Channels
Number of Channels Up to four (#MMH904), or up to eight
(#MMH908)
Maximum Speed 38,400 bps All Channels
Channel Speeds All standard speeds from 150 bps to 38.4K
bps
Data Format Asynchronous: 5, 6, 7, or 8 data bits, with
1,1.5, or 2 stop bits
Parity Odd, even, or none, fully transparent
Local Echo On or off selectable for each channel
Flow Control Xon/Xoff, CTS on/off, or HP ENQ/ACK
selectable for each channel
Pacing On or off selectable for each channel, DTR
on/off, or Xon/Xoff
Interface RS232C/CCITT V.24; 25-pin female D
connectors
1.8.2 System Control
Local Access Through MultiMux’s RS232C “Command
Port” Remote Access Through MultiMux’ s
internal dial-up CCITT V.22bis/V .22, Bell
212A/103 (2400/1200/300 bps) command
modem
Device Any asynchronous keyboard terminal, PC in
terminal mode (local access), or any
standard dial-up 2400/1200/300bps V .22bis/
V.22, 212A/103 modem (remote access)
Command Functions Menu-driven/help screen approach.
Commands to select channel speeds, flow
control methods, listing of parameters, help
screens, storing of configurations, downline
loading, status reporting, echo controls,
resets, pacing parity , stop bits, reponse time
priorities, test modes, modem
configurations, and other parameters.
23
Chapter 1 - Introduction & Description
Diagnostics Memory test, Analog Loop, Digital Loop,
Remote Analog Loop, Switch test, LED test,
Non-Volatile RAM test, W atchdog Timer
1.8.3 Composite LInk
Data Format Synchronous or Asynchronous
Link Speeds Up to 128,000 bps
Link Protocol Proprietary modified HDLC
Error Correction 16-bit CRC block check with ARQ
Interface RS232C/CCITT V.35/V .24, or use MultiMux
integral modem or DSU
1.8.4 33,600 bps Link Modem
Modulation ITU-T V.34; AT&T V.32 terbo; ITU_T V.32bis,
V.32, V.22bis, Bell 212A and 103 (North
America) or B.23 and V.21 (international)
Speeds 300 bps tp 33.6K bps
Commands Fully AT command compatible
Usage Synchronous full duplex over unconditioned
2-wire or 4-wire leased line; asynchronous
half or full duplex over 2-wire dial-up
Line Interface RJ-1 1C jack for dial-up and 2-wire or 4-wire
leased line; in Canada, one CA02B
connector
1.8.5 56,000 bps DSU
Speed 56K, 19.2K, 9.6K, 4.8K, or 2.4K bps
Format Synchronous DDS or compatible
Usage Full duplex over LADS (Local Area Data
Set) or two-pair non-loaded metallic wire
Line Interface DDS interface with an RJ-48 keyed jack
24
Chapter 1 - Introduction & Description
1.8.6 ISDN Terminal Adapter
Description Integral ISDN terminal adapter card
Operating Mode ISDN Basic Rate; 1B+D or 2B+D
Synchronous Data Rates 2.4–128K bps
Clocking Normal network clock (slaved to network
receive clock); private network master
(internal); external clock of DTE data
Commands Menu system
D-Channel Switch A T&T 5ESS®, 5E6; NT DMS-100™, BCS-32
Compatibility Siemens Stromberg-Carlson EWSD®,
National ISDN-1;NEC International Switch
Line Interface 2-wire ISDN Basic Rate 2B1Q U-interface;
ANSI T1.601-1992 compliant; RJ-48 jack
B-Channel Aggregation BONDING Protocol, Mode 1
1.8.7 Command Modem
Description Bell 212A/103 & CCITT V.22bis/V.22
compatible asynchronous, full duplex over
dial-up lines
Speeds 2400, 1200 and 0-300 bps
Line Interface RJ1 1C jack for dial-up line
1.8.8 Electrical/Physical
Voltage 1 15 volts AC (standard). 240 volts AC
(optional)
Frequency 47 to 63 Hz
Power Consumption 35 watts
Operating T emperature 0OC - 40OC
Dimensions 2 5/8" high x 15 3/4" wide x 11" deep; 6.7
cm high x 40.0 cm wide x 28 cm deep
Weight 12 pounds (26.4 kg)
25
Chapter 2 - Configuration
Chapter 2 - Configuration
2.1 Introduction
The MultiMux MMH900 Series is available in two models; the four and
eight channel units with an internal command modem, a composite link
modem or DSU, dial-up capability from a remote location into the
command modem and a command port for local AT command
configuration information.
The configuration of the MultiMux MMH900 series is as follows:
Model Description
MMH904Ca Four channel unit with internal command modem
MMH908Ca Eight channel unit with internal command modem
MMH90XCa/V.34 Internal 28800 bps composite link modem for lease
line with dial back and automatic lease line restoral
MMH90XCa/56 Internal 56000 bps composite link DSU
MMH90XCa/IS Internal ISDN terminal adapter for Basic Rate
Interface Service
27
Chapter 2 - Configuration
2.2 Configuration 1
Configuration 1 is two Multi-Tech MultiMux MMH904Ca/144 which are
four channel multiplexers with internal 28.8K bps composite link modems
linking sites one and two over a 4-wire analog lease line. The local site
has the MMH904Ca/288 connected to a host minicomputer. The remote
site has three terminals and a shared printer connected to the
asynchronous channels of the remote mux. At the remote site, the three
terminals are communicating with the remote mux on 38.4K bps
asynchronous channels and the printer is configured for one setting
above its cps rating. Configuration 1 is shown in Figure 2-1.
Figure 2-1. Configuration 1
Channels 1 through 4 at the local site are connected to channels 1
through 4 at the remote site. The asynchronous channels of the local
mux are configured with XON/XOFF software flow control enabled, so
that the channel buffers in the local mux do not lose data from the host.
With flow control enabled at the local mux, the local mux can tell the host
when it feels that it's dynamic buffers are becoming full. For the same
reasoning, pacing should be enabled at the remote site, if it appears that
data is being lost at the terminals. Pacing allows the terminal to tell the
remote mux not to send any more data until its buffers are cleared.
Pacing should also be active for the printer to ensure that all the data is
received by the printer. The first set of parameters in the following
examples are for the local mux and the second set are for the remote
mux.
28
Chapter 2 - Configuration
Local Channel Parameter
CHN SPD WORD BIT PARITY CONTROL ACK ECHO PACE E IA XON
01 19200 8 1 NONE XON/XOFF OFF OFF OFF OFF OFF
02 19200 8 1 NONE XON/XOFF OFF OFF OFF OFF OFF
03 19200 8 1 NONE XON/XOFF OFF OFF OFF OFF OFF
04 19200 8 1 NONE XON/XOFF OFF OFF OFF OFF OFF
OK
STP FLOW ENQ/ PASS PASS
Configuration 1 Local Site Channel Parameters
Local Channel Parameter
CHN SPD WORD BIT PARITY CONTROL ACK ECHO PACE EIA XON
01 19200 8 1 NONE XON/XOFF OFF OFF XON OFF OFF
02 19200 8 1 NONE XON/XOFF OFF OFF XON OFF OFF
03 19200 8 1 NONE XON/XOFF OFF OFF XON OFF OFF
04 19200 8 1 NONE XON/XOFF OFF OFF XON OFF OFF
OK
STP FLOW ENQ/ PASS PASS
Configuration 1 Remote Site Channel Parameters
29
Chapter 2 - Configuration
2.3 Configuration 2
Configuration 2 is two MultiMux MMH904Ca four channel multiplexers
with two external Multi-Tech MultiModemII MT2834BLs linking the two
sites over an async dial-up line. The MultiModemII's are connected to
the dial-up line and the RS232C interface from the modems is connected
to the EXTERNAL COMPOSITE LINK connector on the back panel of
the MMH904Ca's. The MH904Ca's are set up for an external link device
with a maximum link speed of 57,600 bps. The maximum link speed is
dependent on the compressibility of the data over the link. The
MultiModemIIs are set up for data compression and error correction in
order to achieve the link speed.
Figure 2-2. Configuration 2
The External Composite Link LEDs on the lower left side of the front
panel and the SYSTEM ASYNC LINK LED in the middle of the front
panel of the MMH904Ca's are active for this configuration. The channels
are set up with the same considerations as in Configuration 1.The
composite link configuration may be changed using the List Composite
Link Configuration ($L) command which is shown in the following
example.
LINK LINK MUX MUX EOF XMT EOF RCV LOOP
DEVICE FORMAT SPEED CLOCKING CHARACTER CHARACTER BACK
EXTERNAL ASYNC 57600 EXTERNAL FF FF OFF
Configuration 2 Composite Link Configuration
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