How does one perform a DSU Loopback Test using a Loopback Cable?

DSU Loopback Testing

This test verifies proper DSU operation by matching a transmitted signal to the looped-back receive signal. See Appendix C of the MT64DSU Owner's Manual (document #82034802) for cable description.


Note: The DSU must be in 4-wire dedicated-line mode to perform this test.

1 - Obtain a DSU loopback cable (part #45640100) from Multi-Tech at, or assemble one. See Appendix C for instructions on building the Loopback cable.

2 - Plug the loopback cable into the back panel LINE jack.

3 - Set the DIP switches for Internal Clocking. See Appendix D of the MT64DSU Owner's Manual (82034802).

4 - If you send data from your DTE device, it should be looped back to your DTE device. If you have access to a Bit Error Rate Tester, this can be used in place of the DTE device.