Chapter 3. Test Modes
3-8 DSU 56/64 User Manual 61200062L1-1
Test Pattern (PTRN)When the PTRN test is initiated, the local DSU 56/64 uses the
integral test pattern generator to transmit a standard 2047 test
pattern to the DSU on the far end of the circuit. The local DSU 56/
64 then examines the received data for the standard 2047 patte rn .
Once this pattern is detected and synchronization is achieved, the
ERROR indicator is turned off. The ERROR indicator turns on when
errors in the receive data pattern are detected. While this test is
active, errors can be injected into the transmit data stream by
pressing the SELECT push-button. The PTRN LED flashes during
initialization of the test and turns on solid once the test is in
progress.
To initiate the PTRN test, perform the following steps:
1. Press SELECT seven times to turn on the PTRN test indicator.
2. Press the TEST switch while this test indicator is on.
3. To terminate this test, press TEST.