User`s manual

Testing
5
You can perform three tests on your 8500 series display set ADM: local loopback
test, remote loopback test, and self-test. Taken together, these three tests help
you isolate data communications problems.
Local Loopback Test
The purpose of the local loopback test is to ensure there are no data
transmission errors in the local part of the data transfer circuit (between the data
terminal and the ADM). When the local loopback test is initiated, data travels
from the data terminal to the ADM, where it is looped back to the data terminal.
You can do local loopback tests when the set is idle (local-idle mode) or when it
is engaged in a data call (local-data mode).
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