5.3 LOCAL LOOP DIAGNOSTICS
The Model 2707 offers V.54 loop diagnostics. Use these diagnostics to test the NTU and any communication links. This test can be activated via DIP switches or via signals on the Model 2707 serial port interface.
Operating Local Loopback (LL)
The Local Loopback (LL) test checks the operation of the local Model 2707, and is performed separately on each unit. Any data sent to the local Model 2707 in this test mode will be echoed (returned) to the user device (i.e., characters typed on the keyboard of a terminal will appear on the terminal screen)
.
Figure 7. Local Loopback for a Network Termination Application
To perform a LL test, follow these steps:
1.Activate LL. This may be done in one of two ways:
–Place the DIP switch
–Activate the “LL” signal on the DTE (2707/C only). If you are not sure which lead is the “LL” signal, please refer to Appendix C.
2.Verify that the data terminal equipment is operating properly and can be used for a test.
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