Test Modes - Patton electronics 2450 User Manual

• "Error" glows red when errors are detected in test mode during
the "511" and 511/E" tests. This indicator also glows during
normal operation to indicated framing errors and/or bipolar
violations in 64 Kbps mode, or invalid bipolar violations in 56
Kbps mode (see Figure 7, below).
• "Test" glows red when the V.54 loopback tests or V.52 BER
tests are initiated.

5.2 TEST MODES

The Model 2450 offers two V.54 test modes, plus a built-in V.52
BER test pattern generator, to evaluate the condition of the modems
and the communication link. These tests can be activated physically
from the front panel, or via the interface.
5.2.1 Using Local Analog Loopback (LAL)
The Local Analog Loopback (LAL) test checks the operation of the
local Model 2450, and is performed separately on each unit. Any data
sent to the local Model 2450 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", and; second, by
raising pin 18 on the interface. (Note: Make sure DIP switch S1-7 is
OFF). Once LAL is activated, the Model 2450 transmitter 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 V.52 BER (bit error rate) test as described in Section
5.2.3. 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 2450.
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5.2.2 Using Remote Digital Loopback (RDL)
The Remote Digital Loopback (RDL) test checks the performance
of both the local and remote Model 2450s, and the communication link
between them. Any characters sent to the remote Model 2450 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
2450 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", and; second, by raising
pin 21 on the interface. (Note: Make sure S1-7 is OFF).
2. Perform a V.52 BER test as described in Section 5.2.3. If the
BER test equipment indicates a fault, and the Local Analog Loopback
test was successful for both Model 2450s, you may have a problem
with the twisted pair line between the modems. You should then check
the twisted pair line for proper connections and continuity.
5.2.3 Using the V.52 BER Test
To use the V.52 BER tests in conjunction with the V.54 loopback
tests, follow these instructions:
1. Locate the "511/511E" toggle switch on the front panel of the
2450 and move it UP. This activates the V.52 BER test mode and
transmits a "511" pseudo-rando test pattern into the loop. If any errors
are present, the local modem's red "Error" LED will blink sporadically.
2. If the above test indicates no errors are present, move the V.52
toggle switch DOWN, activating the "511/E" test with errors present. If
the test is working properly, the local modem's red "Error" LED will glow.
A successful "511/E" test will confirm that the link is in place, and that
the Model 2450's built-in "511" generator and detector are working
properly.
Note: The above V.52 BER tests can be used independently of the
V.54 loopback tests. This requires two operators: one to initiate and
monitor the tests at the local Model 2450, and one to do the same at
the remote Model 2450. In this case, the test pattern sent by each
Model 2450 will not be looped back, but will be transmitted down the
line to the other Model 2450. Both operators must initiate and monitor
the tests simultaneously.
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