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Documentation Number 11401198 Manual 11
B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 433-5105
A. Activate LAL. This may be done in one of two ways: First, by
moving the front panel toggle switch DOWN to "LAL". Second, by
raising pin 18 on the interface. (NOTE: Make sure DIP switch
SW1-8 is OFF). Once LAL is activated, the Model 1140 transmit
output is connected to its own receiver. The "test" LED should be lit.
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 BER (bit error rate) test on each unit. If the BER
test equipment indicates no faults, but the data terminal indicates a
fault, follow the manufacturer's checkout procedures for the data
terminal. Also, check the interface cable between the terminal and
the Model 1140.
5.2.2 REMOTE DIGITAL LOOPBACK (RDL)
The Remote Digital Loopback (RDL) test checks the
performance of both the local and remote Model 1140s, and the
communication link between them. Any characters sent to the
remote Model 1140 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 1140 and looped back. To
perform an RDL test, follow these steps:
A. Activate RDL. This may be done in two ways: first, by moving
the front panel toggle switch UP to "RDL". Second, by raising pin 21
on the interface. (NOTE: Make sure SW1-8 is OFF).
B. Perform a BER (bit error rate) test on the system.
C. If the BER test equipment indicates a fault, and the Local
Analog Loopback test was successful for both Model 1140s, you
may have a problem with the twisted pair line between the modems.
You should then check the fiber line for proper connections and
continuity.