AT&T System 25 - Manual (Page 180)

MAINTENANCE
GENERAL MAINTENANCE INFORMATION
System Errors and Alarms
During periodic testing, a maintenance audit could detect a system error that
automatically generates an error record. Depending on severity, the error
record is stored in one of following three tables in the Error Log:
● Permanent System Alarms
●
Transient System Errors
●
Most Recent System Errors.
The three error tables can be displayed at the System Administration
Terminal (SAT). The error tables are used to diagnose and analyze problems,
particularly when the problem has not caused an alarm or when alarms
cannot be retired by replacing faulty units.
The errors are listed in the error tables by time of occurrence. Resolved and
unresolved errors are listed, thus providing a profile of the past and current
state of the system. Error message explanations are provided under “Error
Messages” in this section.
Emergency Transfer
System 25 has emergency transfer capability in case of total system outage.
The Emergency Transfer Unit (ETU) connects preassigned single-line voice
terminals directly to the CO, bypassing the System 25. Emergency transfer is
invoked by loss of ac power or by any failure of the system that prevents it
from processing calls.
Circuit Pack LEDs
During the various states of operation (start-up testing, normal operation, and
failure), CP
Note:
LEDs appear as follows:
The first two listings, Memory and Call Processor, apply only
to Release 1.
The CPU/Memory circuit pack applies to
Release 2 and Release 3.