Multitech MT56DSU-S User manual

MT56DSU-S
Syncronous 56K bps
Data Service Unit
User Guide

MT56DSU-S User Guide
PN: S000327A
Copyright ©2003 by Multi-Tech Systems, Inc.
All rights reserved. This publication may not be reproduced, in whole or in part, without prior written permission from Multi-
Tech Systems, Inc.
Multi-Tech Systems, Inc. makes no representations or warranties with respect to the contents hereof and specifically
disclaims any implied warranties of merchantability or fitness for any particular purpose. Furthermore, Multi-Tech
Systems, Inc. reserves the right to revise this publication and to make changes from time to time in the content hereof
without obligation of Multi-Tech Systems, Inc. to notify any person or organization of such revisions or changes.
Revision Date Description
A 12/30/2003 Initial release of MT56DSU-S User Manual on CD.
Trademarks
MultiTech and the MultiTech logo are trademarks of Multi-Tech Systems, Inc. All other references are trademarks of their
respective companies.
Technical Support
France [email protected] [phone]
India [email protected] [phone]
U.K. [email protected] [phone]
U.S., Canada sup[email protected] 1 800 972-2439
Rest of World sup[email protected] [phone]
World Headquarters
Multi-Tech Systems, Inc.
2205 Woodale Drive
Mounds View, Minnesota 55112 U.S.A.
[phone] or [phone]
U.S. FAX [phone]
Technical Support [phone]
www.multitech.com

Contents
Chapter 1 - Introduction..................................................................................... 5
1.1 Introduction ............................................................................................. 6
1.2 About This Manual .................................................................................. 6
1.3 Description ............................................................................................. 7
1.4 CSU DSU Basics ................................................................................... 7
1.4.1 DSUFunctions .....................................................................................7
1.4.2 CSUFunctions .....................................................................................7
1.5 Features ................................................................................................. 8
1.6 Specifications ......................................................................................... 9
Chapter 2 - Front & Back Panel Descriptions................................................ 10
2.1 Introduction ........................................................................................... 11
2.2 Front Panel ........................................................................................... 11
2.3 Back Panel ........................................................................................... 12
2.3.1 POWERConnector .............................................................................12
2.3.2 RS232Connector................................................................................12
2.3.3 LINEConnector ..................................................................................12
2.4 Switch Settings..................................................................................... 13
2.5 Shunts .................................................................................................. 14
Chapter 3 - Unpacking & Setup....................................................................... 15
3.1 Introduction ........................................................................................... 16
3.2 Unpacking ............................................................................................. 16
3.3 Telecom Safety Warnings ..................................................................... 16
3.4 Setup .................................................................................................... 17
3.5 V.35 Shunt ............................................................................................ 18
Chapter 4 - Diagnostics.................................................................................... 19
4.1 Introduction ........................................................................................... 20
4.1.1 LoopbackTest ....................................................................................20
4.1.2 LineLoopbackTest ............................................................................21
4.1.3 DSULoopback Test............................................................................21
4.1.4 DSU Back-to-Back Test .....................................................................22

Chapter 5 - Service & Warranty....................................................................... 23
5.1 Multi-Tech Systems, Inc. Warranty & Repairs Policies ......................... 24
5.1.1 Warranty .............................................................................................24
5.1.2 U.S.andCanadianCustomers............................................................24
5.1.3 InternationalCustomers(outsideU.S.A.andCanada)........................25
5.1.4 InternationalDistributors.....................................................................25
5.2 Repairs ................................................................................................. 26
5.2.1 RepairProceduresforU.S.andCanadianCustomers ........................26
5.2.2 RepairProceduresforInternationalCustomers...................................26
5.2.3 RepairProceduresforInternationalDistributors..................................27
5.2.4 ReplacementParts .............................................................................27
5.3 Technical Support ................................................................................. 27
5.4 Internet Site .......................................................................................... 27
Appendix............................................................................................................ 28
Appendix A - Application Examples ................................................................ 29
Introduction......................................................................................................29
Local Area Data Set Application ......................................................................29
DDSPoint-To-PointApplication.......................................................................29
DDSMultipoint(Polled)Application .................................................................30
Appendix B - Interface Signals and Connector Pinouts ................................. 31
RJ-48Connector..............................................................................................31
DB25SConnector ............................................................................................32
DB25SConnectorwithV.35Interface .............................................................33
LoopbackCable (MTSP/N45640100)............................................................34
Back-To-BackCable (MTSP/N45050000).....................................................35
Appendix C - Regulatory Information ............................................................. 36
FCCRegulationsforTelephoneLineInterconnection ......................................36
CanadianLimitationsNotice ............................................................................37

Chapter 1 - Introduction

6
Chapter 1 - Introduction
1.1 Introduction
The Multi-Tech Systems MultiDSU, model number MT56DSU-S is a synchronous 56 Kbps data service unit
(DSU). As a combined DSU and Channel Service Unit (CSU), it provides a direct connection to the
DATAPHONE®Digital Service (DDS) network. The MT56DSU-S connects a synchronous Data Terminal
Equipment (DTE) device to remote equipment using DDS network lines at 56 Kbps speeds for point-to-point
and multi-point service.
Figure 1-1. MultiDSU Modem
1.2 About This Manual
Chapter 1 - Introduction contains an introduction to the MT56DSU-S product and its features and functions.
Chapter 2 - Front and Rear Panel Descriptions provides front panel LED descriptions and rear panel
connector descriptions, DIP-switch settings, and an RS232/V.35 shunt description.
Chapter 3 - Unpacking and Setup provides unpacking, safety warnings, setup procedures, and how to
change the shunt from the default RS232 position to the V.35 position.
Chapter 4 - Diagnostic Testing explains how to set up and run a diagnostic test.
Chapter 5 - Service and Warranty provides instructions on getting service for your MultiDSU at the factory, a
statement of the limited warranty, information about our user bulletin board service, and space for recording
information about your MultiDSU prior to calling Multi-Tech's Technical Support. The final three sections
explain how to use our bulletin board service (BBS), and get support through CompuServe and the Internet.
Appendix A - Application Examples illustrates several DSU/CSU uses that may help in understanding your
particular installation site.
Appendix B - Interface Signal and Connector Pinouts lists the various electronic signals and connector
pinouts related to the MT56DSU-S.
Appendix C - Regulatory Information

7
Chapter 1 - Introduction
1.3 Description
The MT56DSU-S is compact, easy to operate and has the features to allow flexibility in meeting your
transmission requirements. The DDS is a service for transmission of digital signals via digital transmission
facilities exclusively. The MT56DSU-S is designed to meet AT&T Technical Publication 62310 requirements.
As such, the MT56DSU-S provides all the functions required on the customer side of the network.
You will find the MT56DSU-S easy to install, use and maintain. It is recommended that you read the entire
manual early in your experience with the MT56DSU-S so you can appreciate all of the MT56DSU-S features
and options.
1.4 CSU/DSU Basics
A DSU (Data Service Unit) and a CSU (Channel Service Unit) are typically connected to provide the interface
between DTE (data terminal equipment) and a DDS or other four-wire network.
The DSU processes serial synchronous digital data over the DDS network or other four-wire unloaded
twisted-pair network.
The MT56DSU-S contains the functions of a DSU and CSU in a single package.
1.4.1 DSU Functions
The DSU encodes data as pulses on the communications line by converting the customer data stream to
bipolar format for transmission over the digital network.
1.4.2 CSU Functions
The CSU terminates the digital circuit at the customer site. It performs line conditioning functions, ensures
network compliance with FCC rules, and responds to test commands (either from the Telco central office (CO)
or from the DSU).
The figure below shows the MT56DSU-S in a basic DDS network installation.
DTE
DDS
Network
DTE
DSU
DSU
Figure 1-2. Basic DSU/CSU Configuration

8
Chapter 1 - Introduction
1.5 Features
The MT56DSU-S provides many useful features. Standard features include V.35 and EIA-232-D interfaces on
the data port (DTE device) and a synchronous rate of 56 Kbps on both the data port and trunk, and user-
selectable clocking option.
Your Multi-Tech DSU/CSU provides the following features:
Supports direct connection to the DATAPHONE Digital Data Service (DDS) or compatible network
Standard EIA-232-D and V.35 interfaces on the data port (DTE device) and DDS interface on the line
• Multiple selectable clocking
- Internal clocking
- DDS (slave) clocking
• Multiple MT56DSU-S-activated diagnostic tests
- Local loopback test
- Digital loopback test
• Multiple Telco-activated diagnostic tests
- DSU loopback test
- CSU loopback test

9
Chapter 1 - Introduction
1.6 Specifications
Model Number: MT56DSU-S
Device Operation: combined DSU and CSU
Data Rates:
Synchronous 56 Kbps (Data port and line)
Interfaces:
Data (RS232) DB25S (female) - Data port
Data (V.35) DB25S (female) - Data port with an adapter cable
Line (DDS) RJ-48 8-position keyed jack - Line
Power Requirements: 115V AC, 50-60 Hz, 2 Watts
Temperature: 32 to 120° F (0 to 50° C)
Humidity: 20 to 90% (non-condensing)
Dimensions: 1" H x 4.125" W x 5.5" D
2.5 cm H x 10.8 cm W x 14.2 cm D
Weight: 8 oz. (224 g)
Certification: FCC Part 15 Class B
FCC Part 68
UL Listed
Compatibility: AT&T Pubs 62310
FIC Codes: 04DU5-56
USOC Jack: RJ-48S
Transmitter/Receiver:
Modulation bipolar return to zero (BRZ)
Transmit Level 1.4V peak (+6dBm) into 135 Ohm at 56 Kbps
OutputImpedance 135 ohms
Receive Levels +6 to -45 dBm
InputImpedance 135 ohms
Delay Times (in secs.) RTS/CTS DCD on DCD off
0.4 0.3 0.2

Chapter 2 - Front & Back
Panel Descriptions

11
Chapter 2 - Front & Back Panel Descriptions
2.1 Introduction
This chapter describes the front panel LEDs and back panel connectors. The front panel has one row of
LEDs. Two back panel connectors provide the data and DDS or LADS connections. A circular power
connector is provided to connect the external power supply.
2.2 Front Panel
The front panel has five LEDs that provide the status of the line. The V35 LED lights if V.35 interface signaling
is used. The line LEDs display status whether the line is transmitting or receiving frames, and line status.
Figure 2-1. Front Panel
TD Transmit Data (TD) LED blinks when data is being transmitted - on for a space and
off for a mark.
RD Receive Data (RD) LED blinks when data is being
received - on for a space and off for a mark.
V35 The V35 LED lights when the shunt is in the V35 position.
NS The No Signal (NS) LED lights when no signal is received from the network or when
the signal is too weak for normal operation.
OOS The Out Of Service (OOS) LED lights when an outage condition occurs. This
happens when there is a failure in the digital service that is detected by the network
and the Telco sends a repetitive OOS sequence.
CD The Carrier Detect (CD) LED lights when a carrier signal is received from the
network.

12
Chapter 2 - Front & Back Panel Descriptions
2.3 Back Panel
All the cable connections, including one power connection and two signal connections, are made at the back
panel of the DSU. The RS232 connector is used to connect the DSU to an RS232 or V.35 device, and the
LINE connector connects to a DDS or LADS (Local Area Data Set) circuit. The cable connections are shown
in Figure 2-2 and defined in the following sections.
POWER
LINE
RS232
Figure 2-2. Back Panel
2.3.1 POWER Connector
The POWER connector is used to connect the external wall type transformer power supply to the DSU. The
wall transformer plugs directly into an AC outlet.
2.3.2 RS232 Connector
The RS232 (Data) connector is used to connect the DSU to a sync device, such as, multiplexers, routers, or
legacy equipment such as cluster controllers. The RS232 connector is a DB-25 female connector located on
the back panel of the DSU.
The RS232 data connector interface can be switched to a V.35 interface. For the V.35 interface, an internal
data shunt has to be moved from the default RS232 position to the V.35 position. To change the shunt, refer
to the "Shunt" paragraph in this chapter. Also refer to Appendix A for special cabling requirements for the
V.35 mode.
2.3.3 LINE Connector
The LINE connector is used to connect the DSU to a 56K DDS circuit or LADS. This connector is an RJ-48
(keyed) jack on the back panel of the unit.

13
Chapter 2 - Front & Back Panel Descriptions
2.4 Switch Settings
An 8-position DIP switch is located on the right side of the MT56DSU-S printed circuit board (when viewed
from the front, as in Figure 2-3). The DIP switch functions are described in the following table.
1 2 3 4 5 6 7 8
DIP-Switch
Figure 2-3. Switch Settings
Table 2-1. Switch Settings
Switch Mode Position Description
1 Reset UP* Normal
DOWN Reset
2 Clocking UP* DDS
DOWN Internal
3 Loopback UP* Normal
DOWN Loopback
4-8 Not Used
*Factory default setting

14
Chapter 2 - Front & Back Panel Descriptions
2.5 Shunts
V.35 signal levels are more reliable for high speed data and/or longer cable distances. For higher speeds
and/or longer distances, V.35 is preferred. EIA-232-D signal levels are intended for data rates of 19.2 Kbps or
less and cable lengths of 50 feet or less.
There are two shunt positions in the middle left side of the printed circuit board that configure the data port for
either RS232 or V.35 operation. The shunt positions are shown in Figure 2-3.
V.35 Shunt Position RS232 Shunt Position
Figure 2-3. Shunts
The shunt position closest to the DIP switches is for RS232 data interface and the other one is for V.35 data
interface. The shunt is shown in the RS232 (default) position in Figure 2-3. To change the position of a
shunt, refer to the V.35 Shunt in Chapter 3.

Chapter 3 - Unpacking & Setup

16
Chapter 3 - Unpacking & Setup
3.1 Introduction
This chapter describes the unpacking of the DSU, cable connections depending on whether EIA-232-D or
ITU-T V.35 interface signaling is used on the data port, and how to configure the unit dependent on your site
situation. Once the DSU is configured, then the data port can be connected to your data device.
3.2 Unpacking
The shipping box contains the DSU, power adapter, and a documentation CD with a User's Guide. Inspect
the contents for signs of any shipping damage. If damage is observed, do not power up the unit, contact
Multi-Tech's Technical Support for advice (refer to Chapter 5 - Warranty). If no damage is observed, place
the DSU in its final location and verify the signal levels (EIA-232-D or ITU-T V.35) for the data port, and
connect your cables, phone lines, and power supply.
3.3 Telecom 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 for use with UL and cUL listed computers.
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.
8. To reduce the risk of fire, use only 26AWG or larger telecommunications cord.

17
Chapter 3 - Unpacking & Setup
3.4 Setup
Perform the following procedure to connect your cables and, if necessary, change to V.35 signaling on the
data port.
1. If the DTE device has a V.35 interface, the internal shunt must be moved to the V.35 position and a V.35
adapter cable must be connected to the data connector (labeled “RS232”). Refer to V.35 Shunt for
procedures on moving the shunt to the V.35 position. Refer to Appendix A for cable details.
If the DTE device has an EIA-232-D interface, a standard RS232 (straight-thru) cable can be used.
POWER
LINE
RS232
To Power Outlet
To DTE Device
To Line Jack
Figure 3-1. Back Panel Connections
2. Connect the external wall transformer power supply to the DSU, then plug the power supply into a live
AC outlet. The DSU has no power switch; however, when power is applied to the unit, the front panel
LEDs will light.
3. Connect the DTE device to the RS232 connector on the back of the DSU.
4. Connect an RJ-48 phone cable to the LINE connector on the back of the DSU. Connect the other end of
the phone cable to the local access line jack.

18
Chapter 3 - Unpacking & Setup
3.5 V.35 Shunt
Either EIA-232-D or ITU-T V.35 electrical signal interface can be selected on the Data connector. Units are
shipped with EIA-232-D signal levels selected. Use the following procedure to select V.35.
CAUTION : This procedure requires opening the unit. Like most products of this type, this product contains
components that are sensitive to static and static discharge. Use your best efforts to avoid static discharge
when contacting the components inside this unit.
WARNING: Always disconnect the power cord before opening the enclosure to avoid any chance of electric
shock.
1. Unplug the power cord.
2. The enclosure consists of two halves. Using a Phillips screwdriver, remove the two screws from the
bottom of the unit. Remove the top half.
3. Carefully pry the shunt out of its RS232 socket and insert it into the V.35 socket.
V.35 Shunt Position RS232 Shunt Position
Figure 3-2. Shunts
4. Carefully reassemble the unit, making sure no foreign objects are accidentally left inside.
5. The DSU is now configured for V.35 signal levels. To connect to a device with a 34-pin Winchester
female V.35 connector, use an adapter cable with a 25-pin female connector at one end and a 34-pin
Winchester male connector at the other end. Using the signal pin designations in Appendix A, you can
make or order a cable from most any cable vendor.

Chapter 4 - Diagnostics

20
Chapter 4 - Diagnostics
4.1 Introduction
The DSU is set to a default of Normal (non-diagnostic) mode at the factory. When diagnostics are to be run,
change the Loopback DIP switch as described in Chapter 2 of this manual.
When a failure occurs in the digital facility (Telco equipment), the network will detect the failure and send a
repetitive OOS signal sequence to your equipment. Your equipment can detect local loop failure by the
absence or distortion of the digital signal. If an OOS is received when data is expected, check the remote (far-
end) transmitting equipment. If the remote equipment is transmitting properly, contact your telephone
company. If the Telco is required to perform remote tests, the channel will be temporarily interrupted and loss
of data may occur.
The following sections describe the tests that are available for the DSU.
4.1.1 Loopback Test
This test allows you to test the local DTE and local DSU. Use the following steps to perform the Loopback
Test.
1. Set DIP switch #3 to the down position.
2. Send data from your DTE, it should be “looped back” to your DTE. If you have access to a Bit Error Rate
Tester, this can be used in place of the DTE.
DTE
(Or BERT Tester) Local DSU
(In Loopback Test Mode)
Figure 4-1. Loopback Test Diagram