Fault Detection And Isolation - Northern Telecom DMS-100 Series Maintenance Manual

Fault detection and isolation

Fault detection on the PLD is accomplished through continuous
self-monitoring of the system, routine audits, and both automatic and
manual diagnostic procedures. Fault isolation can be performed to circuit
card level, that is, the fault can be identified as either a BIC or a PIC failure.
If a hardware or link fault occurs on the PLD, the fault status code LCM is
displayed below the peripheral module (PM) subsystem. The PLD becomes
system busy (S), the LCM is set to in-service trouble (ISTb), and all
associated lines are removed from service and set to line module busy
(LMB).
Log report PM181 provides the reason for the hardware failure, which can
be one of the following:
•
•
Log report PM179 provides the reason for the link failure, which can be any
of the following:
•
•
•
•
•
•
Once link alarms have been cleared, all associated lines are set to the idle
state and log report PM179 is generated to indicate that the alarms have
been cleared.
For more detailed information on log reports, refer to the PCM30 Line
Drawer Planning, Engineering, and Administration Guide, 297-2101-115.
If a fault occurs on the Mercury exchange line multiplexer that brings down
the PCM30 link, the PLD becomes system busy (S). All associated lines are
removed from service and set to line module busy (LMB) until the fault is
corrected.
BIC failure
PIC failure
PIC not equipped (CARD OUT)
local loss of frame alignment (LLFA)
local loss of multiframe alignment (LLMA)
remote frame alignment indication (RFAI)
remote multiframe alignment indication (RMAI)
alarm indication signal (AIS)
PCM30 Line Drawer Maintenance Guide BCS33 and up
PCM30 line drawer maintenance 2-3