Test Mode Operation

Remote Digital Loopback with Self Test &T7

After making the data connection, enter the escape sequence to return to command mode. Entering &T7 places the remote modem in digital loopback provided the remote operator enters &T4 to allow an RL request. Once in RDL/TP, the local modem transmits a test pattern and automatically verifies that the remote modem is looping the pattern back (Figure 7-5). Enter &T to exit RDL/TP and return to command mode. Enter the O command to return online in data mode.

Exiting RDL/TP the modem responds with a three digit value between 0 and 255 representing the number of errors which occurred during test pattern detection. If errors occur, repeat the test several times to verify the consistency of the problem, then use the analog loopback tests to isolate the problem.

Figure 7-5. Local Modem Initiating Remote Digital Loopback with Test Pattern

Test Pattern %T

In Test Pattern, transmitted data from the local DTE is blocked and replaced by a V.52 compatible test pattern. When the modem transmits the test pattern, it expects to receive the same pattern.

Bilateral Digital Test Enable / Disable *DG Enable or disable bilateral test functions.

Command

Operation

 

 

*DG

Bilateral digital loop disabled

 

 

*DG1

Bilateral digital loop enabled

 

 

Modem 3600

7-7

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Black Box 3600 MODEM manual Remote Digital Loopback with Self Test &T7, Test Pattern %T