Isolating Problems Using Loopback Data Tests
D-4 Issue 2 November 1996

Performing a Local Loopback Test

To initiate the test, type:
AT&T1
Type any string of characters. Compare the characters on the screen with those
you typed. If the data does not match, troubleshoot your EIA Connector cord
and terminal. If these are operating correctly, your data module may be
defective. Call the Lucent Technologies Technical Service Center at
1 800 242-2121.
This test will continue for the period of time indicated in S-register S18. To
terminate the test before the test timer expires, type:
+++
The system responds with:
OK
Type:
AT&T0
The system responds with:
OK
Local Loopback Test with Self-Test
This test evaluates the data modules transmit and receive circuitry by having
the data module generate test characters internally. At the end of the test, the
8400B Plus Data Module displays a three-digit number indicating the num ber of
errors that occurred during the test. If you receive an error count other tha n
zero, you may have a defective data module. Call the Lucent Technologies
Technical Service Center at 1 800 242-2121.
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