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Isolating Problems Using Loopback Data Tests
D-6 Issue 2 November 1996
If an error count other than 000 is returned, repeat this test procedure. If the
error count is still other than 000, this indicates a problem within the data
module. Call the Lucent Technologies Technical Service Center at
1 800 242-2121.
Remote Loopback Test
This test evaluates the quality of the data transmission channel, and verifies the
proper operation of the 8400B Plus Data Module, the local terminal, and the
remote data module.
This test can only be performed with a remote data module capable of
supporting a Remote Loopback Test. The remote DCE must be configured to
loop the characters back to the 8400B Plus Data Module. If the remote endpoint
is an 8400B Plus Data Module, its user must issue an AT&T4 command. This
provisions the data module to accept a remote loopback request. If the remote
data module does not respond to the Remote Loopback Test request, the test
request will be aborted.
Using this test, you will generate your own test message. Once you establish a
call and initiate the test, the following occurs:
■ data is transmitted through the 8400B Plus to the remote DCE,
■ the remote DCE is put into remote loopback mode, and then
■ the data is looped back through the 8400B Plus to your data terminal
equipment.
You can then compare the received message with the transmitted message.
Passing the test indicates that all elements of data transmission are operating
properly, at least up to and through part of the remote endpoint. If data errors
occur during normal data-transmission mode, the problem is further into the
remote endpoint, or its attached data terminal equipment.
Failing this test does not necessarily indicate that the 8400B Plus Data Module
is defective. Should this occur, perform both a Local Loopback Test and then a