Nortel DMS-100 Series Maintenance Manual page 373

problem indicators for each type of fault. Actions that the CM and the
operating company personnel must take appear under each trouble indicator.
The three types of parity faults are as follows:
An intermittent fault. This fault occurs when the SMS detects a parity
error and does not find an error during the read over of the location.
A soft fault. This fault occurs when the SMS detects a parity error and
finds an error during the read over of the location. The SMS does not
find an error when the SMS tries to write to the location. The error can
occur in the program store or the memory store.
A hard fault. This fault occurs when the SMS detects a fault and cannot
read or write to the memory location. In this event, the hardware is
defective. To correct the fault, replace the associated memory card.
Types of actions that the CM takes
When the SMS detects a parity fault, the CM takes action to correct the
fault. These actions depend on the type of parity fault and the state of the
SMS. The CM can set the defective unit as SysB and trigger the correct
recovery action. The CM can set the defective unit as ISTb. A defective
active unit or the inactive INSV unit affect the course of CM action. The
CM actions control the steps the operating company personnel must take.
The CM informs operating company personnel through the PM181 log that
the system found a parity fault. This log is the primary problem indicator.
Operating company personnel can check for associated logs like PM128 to
understand the actions that the CM takes.
The header of the following sections is the PM181 log. The header includes
the message that informs the maintenance personnel of the parity fault type.
Associated log reports and problem indicators appear under each header.
The response to the
>QUERYPM FLT
personnel of the action the CM performs to correct the fault. The actions
that the operating company personnel must take appear after each subset of
indicators.
The following two conditions control the actions that the CM performs:
Both units are in-service.
Only the active unit is in-service.
The following examples describe the reasons that these conditions control
the action that the CM performs.
PM181—Hard parity fault, both units INSV
The following is an example of a PM181:
command informs operating company
DMS-100 Family SMS Maintenance Manual XPM10 and up
Trouble isolation and correction 9-9