ADTRAN DSU 5600 User Manual

1 8 DSU 5600 User Manual 61200.078L1-1Chapter 3. Test ModesDTE and Loop Test (LL)The DTE and Loop test is initiated at the local DSU 5600 andallows independent testing of the separate sections of the DSU5600. First, it allows the local DTE interface to be tested with datafrom the terminal or test equipment. Second, it allows the loopinterface section of the local DSU 5600 to be tested from theremote site over the actual communications circuit. Testing fromthe remote end of the circuit is done with test data generated bythe remote DSU or terminal type test equipment.The DTE and Loop test splits the DSU 5600 into separate DTEand Loop interface sections and then loops the transmit data ofeach interface back to its respective receive data. A block dia-gram illustrating the loopback points and the signal paths forthis test is shown in Figure 3-3.To initiate the DTE and Loop test, perform the following steps:1. Press Select three times to turn On both the DTE and Looptest indicators.2. Press Test while these test indicators are On. The DTE andLoop LEDs Flash during initialization of the test and turn Onsolid once the test is in progress.To terminate this test, press Test.