Multi-Tech Systems MT56DSU-S manual Loopback Test Diagram

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Chapter 4 - Diagnostics

4.1Introduction

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

Local DSU

(Or BERT Tester)

(In Loopback Test Mode)

Figure 4-1. Loopback Test Diagram

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Contents MT56DSU-S Syncronous 56K bps Data Service Unit User GuideRevision Date Description Contents Service & Warranty Introduction Introduction About This ManualDescription CSU/DSU BasicsDSU Functions CSU FunctionsFeatures Specifications Front & Back Panel Descriptions Front Panel Front PanelPower Connector 2 RS232 ConnectorLine Connector Back PanelSwitch Settings Switch Settings Mode Position DescriptionShunts ShuntsUnpacking & Setup Telecom Safety Warnings UnpackingSetup Back Panel ConnectionsV.35 Shunt Diagnostics Loopback Test Diagram Loopback TestLine Loopback Test DSU Loopback TestDSU Back-to-Back Test Diagram DSU Back-to-Back TestService & Warranty 2 U.S. and Canadian Customers Multi-Tech Systems, Inc. Warranty & Repairs PoliciesWarranty International Customers outside U.S.A. and Canada International DistributorsRepairs Repair Procedures for U.S. and Canadian CustomersRepair Procedures for International Customers Technical Support Internet SiteAppendix Appendix a Application Examples IntroductionLocal Area Data Set Application DDS Point-To-Point ApplicationDDS Multipoint Polled Application Figure A-3. DDS Multipoint Polled ApplicationAppendix B Interface Signals and Connector Pinouts RJ-48 ConnectorDB25S Connector Pin Description SignalDB25S Connector with V.35 Interface Pin DescriptionLoopback Cable MTS P/N Build InstructionsFigure B-7. Back-toBack Cable Connector Back-To-Back Cable MTS P/NAppendix C Regulatory Information FCC Regulations for Telephone Line InterconnectionCanadian Limitations Notice S000327A