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

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

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