User's Manual

Test Mode Operation
7-4 Modem 3600
For 2-wire operation, Analog Bilateral Loopback is invalid. In 4-wire
operation, Analog Bilateral Loopback connects the receive line to the
transmit line through a buffer amplifier.
Test the local DTE and cable by entering the &T1 command. Enter a test
message and verify it is echoed on the screen. If it is not returned
exactly as entered, the terminal equipment or data cable is at fault.
To determine if the data cable is defective replace it with a properly
configured cable with electrical continuity. If the cable checks out but
the problem remains, the DTE is defective.
If all local equipment checks out, proceed to the“Testing the Remote
Modem” section on page 7-5.
Issue an escape sequence followed by &T1 to exit analog loopback.
Local Analog Loopback with Self Test &T8
When the modem is offline in command mode, enter the &T8 command
to put the modem in Self Test Local Analog Loopback (Figur e 7-2).
The modem transmits a test pattern. The test pattern is looped back to
the receiver and checked for errors. Entering the &T command causes
the modem to exit Self Test Analog Loopback. The modem responds
with a three digit value between 0 and 255 representing the number of
errors during test pattern detection. If errors occur, repeat the test to
verify the consistency of the problem.
Figure 7-2. Local Analog with Test Pattern