Multi-Tech Systems MT56DSU-S manual DSU Back-to-Back Test Diagram

Page 22

Chapter 4 - Diagnostics

4.1.4 DSU Back-to-Back Test

This test lets you connect two DSUs with a back-to-back cable to verify proper DSU operation. Using a DSU that is known to be operational, you can test a second DSU that is suspect.

1.Obtain a DSU Back-to-Back cable (#45050000) from Multi-Tech, or assemble one. Refer to Appendix B for instructions on building the Back-to-Back cable.

2.Plug the cable into each DSU’s Line jack.

3.On the “good” DSU, set DIP switch #3 to the down position.

4.Set one DSU to internal clocking and the other DSU to DDS clocking.

5.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	“Suspect”	Back-to-Back	“Good” DSU in
	DSU	Cable	Loopback Mode

Figure 4-4. DSU Back-to-Back Test Diagram

22

Image 22

Contents MT56DSU-S Syncronous 56K bps Data Service Unit User GuideRevision Date Description Contents Service & Warranty Introduction Introduction About This ManualDSU Functions DescriptionCSU/DSU Basics CSU FunctionsFeatures Specifications Front & Back Panel Descriptions Front Panel Front PanelLine Connector Power Connector2 RS232 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 Warranty Multi-Tech Systems, Inc. Warranty & Repairs Policies2 U.S. and Canadian Customers International Customers outside U.S.A. and Canada International DistributorsRepair Procedures for International Customers Repair Procedures for U.S. and Canadian CustomersRepairs Technical Support Internet SiteAppendix Local Area Data Set Application Appendix a Application ExamplesIntroduction 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