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4.1.2 Line Loopback Test
This test enables you to test the local DTE, the local DSU, the communications link, and the remote DSU. Use
the following steps to perform the Trunk Loopback Test.
1.
Set DIP switch #3 on the remote DSU to the down position.
2.
Send data from the local DTE, it should be looped back to the local DTE. If you have access to a Bit Error
Rate Tester, this can be used in place of the local DTE.
4.1.3 DSU Loopback Test
This test lets you verify proper DSU operation by matching a transmitted signal to the "looped-back" receive
signal. Refer to Appendix B for cable description.
1.
Obtain a DSU Loopback cable (#45640100) from Multi-Tech, or assemble one. Refer to Appendix B for
instructions on building the Loopback cable.
2.
Plug the Loopback cable into the back panel Line jack.
3.
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.
Local DTE
Local DSU
(or BERT Tester)
Figure 4-2. Line Loopback Test Diagram
DTE
Figure 4-3. DSU Loopback Test
Network
Remote DSU
(In Line Loopback Test Mode)
Loopback
Cable
DSU
being tested
Chapter 4 - Diagnostics
21
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