24
ASYNC/SYNC INDUSTRIAL LINE DRIVER
5.4.2 R
EMOTE
D
IGITAL
L
OOPBACK
(RDL)
The Remote Digital Loopback (RDL) test checks the performance of both the
local and remote Line Drivers and the communication link between them. In this
test mode, any characters sent to the remote Async/Sync Industrial Line Driver 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 Line Driver and looped back.
To perform an RDL test:
1. Activate RDL. You can do this in one of two ways: By moving the front-panel
toggle switch to Remote or by raising pin 21 on the RS-232 interface (make
sure DIP-switch S3-6 is ON and DIP-switch S2-6 is OFF).
2. Perform a BER-test (bit error rate) 511/511E test on the system. If the BER-test
equipment indicates a fault, and the Local Analog Loopback test was
successful for both Line Drivers, you may have a problem with the twisted-pair
line between the Line Drivers. Test the twisted-pair line for proper
connections and continuity.
5.4.3 U
SING THE
V.52 BER T
EST
I
NDEPENDENTLY
The V.52 BER test can be used independently of the V.54 loopback tests. This
requires two operators: one to initiate and monitor the test at the local Line Driver,
and one at the remote Line Driver.
To use the V.52 BER test by itself, both operators should simultaneously follow
these steps:
1. Locate the 511/511E toggle switch on the front panel and move it UP. This
activates the V.52 BER test mode and transmits a 511 test pattern to the other
Line Driver. If any errors are present, the receiving Line Driver’s red ERROR
LED will blink sporadically.
NOTE
For this test to work, the 511 switch on both Line Drivers must be on.
2. If the test indicates no errors are present, move the V.52 toggle switch DOWN,
activating the 511/E test with periodic errors present. If the test is working
properly, the receiving Line Driver’s yellow ERROR LED will blink regularly. A
successful 511/E test will confirm that the link is in place, and that the Line
Driver’s built-in 511 generator and detector are working properly.