A.Activate local loopback by moving the front panel toggle switch DOWN to “Local”. Once local loopback is activated, the Model 1180 transmit output is connected to its own receiver. The “test” LED should glow. Note: Even though the local Model 1180 cannot communicate with the remote Model 1180 in this mode, the synchronized connection between the two modems remains intact.
B.Verify that the data terminal equipment is operating properly and can be used for a test. If a fault is indicated, call a technician or replace the unit.
C.Perform a BERT (bit error rate) test on each unit. If the BERT test equipment indicates no faults, and the data terminal indicates a fault, follow the manufacturer’s checkout procedures for the data terminal. Also, check the
5.3.2REMOTE LOOPBACK
The remote loopback test checks the performance of both the local and remote Model 1180s, and the communication link between them (Figure 7). Any characters sent to the remote Model 1180 in this test mode will be returned back to the originating device. For example, characters typed on the keyboard of the local terminal will appear on the local terminal screen after having been passed to the remote Model 1180 and looped back. To perform a remote loopback test, follow these steps:
A.Activate remote loopback by moving the front panel toggle switch UP to “Remote”. The “test” LED should glow.
B.Perform a BERT (bit error rate) test on the system.
C.If the BERT test equipment indicates a fault, and the local loopback test was successful for both Model 1180s, this suggests a problem with the fiber communication line connecting the modems. You should then test the fiber line for proper connections and continuity.
5.4POWER-DOWN
Turn off the Model 1180 by simply unplugging the AC power adapter from the wall. There is no power switch on the Model 1180.
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Figure 7. Local and remote loopback test modes
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