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5.3 TEST MODES
The Model 1140RC offers two V.54 test modes and two V.52 test
modes to evaluate the condition of the modems and the communication
link. Both sets of tests can be activated physically from the front panel.
The V.54 test can also be activated from the RS-232 interface.
Note:
V.54 and V.52 test modes on the Model 1140RC are available for point-
to-point applications only.
5.3.1 LOCAL ANALOG LOOPBACK (LAL)
The Local Analog Loopback (LAL) test checks the operation of the
local Model 1140RC, and is
performed separately on each unit.
Any
data sent to the local Model 1140RC 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 upper front panel toggle switch RIGHT to “Analog”.
Second, by raising pin 18 on the RS-232 interface (note: be
sure DIP switch S2-8 is off). Once LAL is activated, the Model
1140RC 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.
3. Locate the lower of the two toggle switches on the front panel
of the Model 1140RC and move it to the right. This will
activate the V.52 BER test mode and inject a “511” test pattern
into the local loop. If any errors are present in the loop, the
red “Error” LED will blink sporadically.
4. If the BER test indicates
no errors
are present, move the V.52
toggle switch to the left, thus activating the “511/E” test with
periodic errors. If the test is working properly, the red “Error”
LED will light. A successful “511/E” test will confirm that the
loop is in place, and that the Model 1140RC’s built-in “511”
generator and detector are working properly.
5. If the BER test indicates that errors
are
present, check to see
that the RS-232 cable connecting the DTE to the Model
1140RC is wired straight through, and is plugged in properly.
Also, ensure that the Model 1140RC is configured properly.
Then re-check your DTE equipment. If you still have errors,
call Patton Technical Support at (301) 975-1007.
5.3.2 REMOTE DIGITAL LOOPBACK (RDL)
The Remote Digital Loopback (RDL) test checks the performance of
both the local and remote Model 1140RCs,
and
the communication link
between them. Any characters sent to the remote 1140RC 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
1140RC 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 upper front panel toggle switch LEFT to “Remote”.
Second, by raising pin 21 on the RS-232 interface. (Note: be
sure DIP switch S2-8 is off).
2. Verify that the DTE equipment on the local end is operating
properly and can be used for a test.
3. Locate the lower of the two toggle switches on the front panel
of the 1140RC and move it to the right. This will activate the
V.52 BER test mode and inject a “511” test pattern into the
remote loop. If any errors are present in the loop, the red
“Error” LED will blink sporadically.
4. If the BER test indicates
no errors
are present, move the V.52
toggle switch to the left, thus activating the “511/E” test with
periodic errors. If the test is working properly, the red “Error”
LED will light. A successful “511/E” test will confirm that the
loop is in place, and that the Model 1140RC’s built-in “511”
generator and detector are working properly.
5. If the remote BER test indicates that errors
are
present, and
the local analog loopback/BER tests showed that both Model
1140RCs were functioning properly, this suggests a problem
with the twisted pair communication line connecting the two
modems. A common problem is improper crossing of the
pairs. Also, verify that the modular connections are pinned
properly, and the twisted pair line has continuity. If you still
have errors, call Technical Support at (301) 975-1007.
5.3.3 USING THE V.52 BER TEST INDEPENDENTLY
The Model 1140RC's V.52 BER test can be used independent of the
V.54 loopback tests. This requires two operators: one to initiate and
monitor the test at both the local and the remote Model 1140RC. To
use the V.52 BER test by itself, both operators should simultaneously
follow these steps: