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ASYNC/SYNC 2-WIRE SHORT-HAUL MODEMS
5. Troubleshooting
5.1 Diagnostic Testing
If you have problems with data communication on your Async/Sync 2-Wire Short
Haul Modem system, or if you just want to verify proper system operation, the
A/S2W SHM has diagnostic capabilities that can help you. You can use the A/S2W
SHM’s front-panel pushbuttons to control different kinds of tests with which you
can quickly check the A/S2W SHM, the attached cables (including the
transmission line), and the local DTE. By performing these tests, you can quickly
find out which components of your A/S2W SHM system are operating properly
and which aren’t.
Before you begin testing, make sure that both of the A/S2W SHMs and both
DTEs are powered up and configured normally. When you have verified this,
perform the tests described in
Sections 5.1.1
,
5.1.2
, and
5.1.3
, in that order.
5.1.1 L
OCAL
A
NALOG
L
OOPBACK
Use this test to check the performance of the local modem, the local DTE, and the
cables between them. Perform this test separately at both the local and remote sites
(refer to Figure 5-1 on the next page). Take these steps:
1. Push the local A/S2W SHM’s ANA (Local Analog Loopback) button or (if the
unit’s LLB jumper is set to EN) raise the LL signal from the DTE to the unit.
The unit should light its TEST LED as it internally connects its transmitter
output to its own receiver circuits.
2. Verify that the DTE is operating properly and can be used for a test. If the
DTE is malfunctioning, replace it or have it repaired.
3. Observe what happens to test data that you send and get back: Set the DTE to
half duplex and get an “echo” through the system and/or use special Bit
Error Rate Test (BERT) equipment.
Summary of Contents for ME375A-R2
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