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LDM-144LR
5. Tests and Diagnostics
5.1 General
This chapter contains procedures for performing system diagnostics and fault-
isolation for both the LDM-144LR and LDM-144LR Card units.
• The LDM-144LR features CCITT V.54 diagnostic capabilities for
performing local analog loopback and local and remote digital loopbacks.
• The loopbacks can be activated by either the front-panel push buttons or
by control signal from the digital interface.
• The LDM-144LR has a built in BER tester and pattern generator which
can be activated via the front panel switches.
5.2 V.54 Loop Tests
The LDM-144LR supports three types of loopbacks for checking the
communication between the attached equipment and the local modem, and
the communication between the modems. Use the test procedures provided
in this chapter to verify normal system operation and to isolate faulty
equipment in the event of failure.
NOTE
Before testing the operation of the data-system equipment and its line
circuits, make sure that all units are turned on and configured correctly.
Loop tests are best performed in the order presented here.
5.2.1 L
OCAL
T
EST
—L
OCAL
A
NALOG
L
OOPBACK
(ANA)
The local Analog loopback (ANA) test checks the performance of the local
LDM-144LR modem, the local data terminal and the connections between
them as shown in
Figure 5-1
. It is performed separately at the local and the
remote site.
1. Activate the ANA loopback (see
Table 4.1
for activation instructions).
The TEST indicator should light. The LDM-144LR digital interface is
now connected to its own DTE data output via most of the modem
circuits. (This test can also be activated via the appropriate pin on the
digital interface.)
