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4.2 TEST MODES
The Model 2155 has a built-in proprietary loopback test mode, plus a
built-in V.52 BER test pattern generator, for evaluating the communica-
tion link. These tests can be activated from the front panel of the
Model 2155 Ethernet Extenders.
Remote Digital Loopback (RDL)/V.52 (BER)
The Remote Digital Loopback (RDL) test checks the communication link
between two Model 2155s.
Figure 8.
Remote digital loop
To use the Remote Digital Loopback tests, do the following:
1. Locate the 511/RDL toggle switch on the front panel of the 2155 and
move it DOWN. This initiates the RDL and sends a 511 pattern into
the loop. If any errors are present, the local modem’s red “ER” LED
will blink.
2. If the above test indicates no errors are present, move the toggle
switch UP, activating the 511E/RDL test (with errors present). If the
test is working properly, the local modem’s red “ER” LED will blink
approximately once per second. A successful 511E/RDL test will
confirm that the link is in place, and that the Model 2155’s built-in
“511” error generator and detector are working properly.
RDL initiated
Remote 2155
Local 2155
