Nortel DMS 100 Series Maintenance Manual page 305

company personnel enter the QUERYPM FLT command, the response
includes the following statement:
NON-CRITICAL HARDWARE FAULT
Operating company personnel must perform the following steps:
1. Test both units to confirm the audit result.
2. Bsy the inactive unit, set the unit to Offl, and replace the defective circuit
cards listed.
3. Return the inactive unit to service.
The node can remain ISTb for more than 5 min and the response to the
QUERYPM FLT command does not change. If this condition occurs, the fault
can be in the active unit. If the RTS of the inactive unit is successful, perform
the following steps:
1. Switch the activity of the units.
2. Busy the newly inactive unit.
3. Test the inactive unit.
4. Set the unit with the damaged circuit cards to Offl. Replace the defective
circuit cards with good circuit cards.
5. Return the inactive unit to service.
Handling a parity error fault
If the system detects a parity fault, you can correct the fault without a loss of
service. This section provides information on the types of parity faults. This
section provides an overview of the actions the CM takes to handle parity
faults. This section includes the actions operating company personnel must
take.
The three types of parity faults are
• An intermittent fault, which occurs when the system detects a fault. The
system does not detect an error during the reread of the location.
• A soft fault occurs when the system system detects a parity error, and an
error when the XPM attempts to reread the location. The system cannot
detect an error when the XPM attempts to write to the location. The error
can occur in the program store or the memory store.
• A hard fault occurs when an XPM detects an error. The XPM cannot
reread and cannot write to the memory location.
When a parity fault occurs, the CM determines the action to perform on the
XPM unit. The action the CM determines depends on the status of the unit that
DMS-100 Family Remote Switching Center Multi-Access Maintenance Manual XPM11 and up
RSC-M trouble isolation and correction 8-17