AT&T MERLIN LEGEND Installation & Maintenance Manual page 484

Maintenance and Troubleshooting
The tests check hardware and software that are in service but do
not disrupt normal service. Any errors detected are registered in
the error logs. Errors are corrected automatically whenever
possible. As necessary, automatic testing causes an alarm.
Demand Tests
Demand diagnostic tests for the line/trunk and station modules
are selected and scheduled by using the menu screens.
Demand tests
increase the effectiveness of on-site troubleshooting and
repair
verify complaints of malfunctioning equipment
Note: For some modules, the demand test does not test the
shared memory.
When a demand test fails, the module being tested either was
not busied-out or is faulty and may have to be replaced.
To run demand tests, the processor module, the power supply
module, and the MLX-20L telephone or PC must be working.
Note: You cannot run a demand test on the 008 MLX module to
which the MLX-20L telephone is attached. However, you can run
a demand test on this module from the PC.
To run a demand test, you must take the equipment out of
service. You can choose "Busy-Out" or "Reset" to do this, but
"Busy-Out" is preferred since:
Busy-out removes lines and stations as they become idIe but
does not disrupt calls in progress.
Reset drops all calls in progress and removes equipment
from service.
5-6 Maintenance