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5.4 V.54 TEST MODES
The Model Series offers two V.54 test modes to evaluate the condition of
the modems and the communication link. These tests can be activated
physically from the front panel, or via the RS-232 interface
Note
V.54 test modes are available for point-to-point applications
only.
Local Analog Loopback (LAL)
The Local Analog Loopback (LAL) test checks the operation of the local
Model 1080A Series unit, and is performed separately on each unit. Any
data sent to the local Model 1080A in this test mode will be echoed
(returned) back to the user device. For example, characters typed on the
keyboard of a terminal will appear on the terminal screen. To perform a
LAL test, follow these steps:
1. Activate LAL. This may be done in one of two ways: First, by moving
the front panel toggle switch DOWN to "Local". Second, by raising
pin 18 on the RS-232 interface (Note: Make sure DIP switch S2-6 is
OFF, and DIP switch S3-5 is ON). Once LAL is activated, the Model
1080A Series' transmit output is connected to its own receiver. The
"test" LED should be lit.
2. 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.
3. 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 RS-232 interface cable between the terminal and
the Model 1080A.
Remote Digital Loopback (RDL)
The Remote Digital Loopback (RDL) test checks the performance of both
the local and remote Model 1080As, and the communication link
between them. Any characters sent to the remote 1080A in this test
mode will be returned back to the originating device. For example, char-
acters typed on the keyboard of the local terminal will appear on the local
terminal screen after having been passed to the remote Model 1080A
and looped back. To perform an RDL test, follow these steps:
1. Activate RDL. This may be done in two ways: First, by moving the
front panel toggle switch UP to "Remote". Second, by raising pin 21
on the RS-232 interface.
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