5-8 Series 90™-70 Enhanced Hot Standby CPU Redundancy User's Guide May 2000 GFK-1527A
5
Configurable Faults
The table below shows the configurable faults and their fault action defaults. There are three fault
actions: Fatal, Non-Fatal, and Conditionally Fatal. Fatal always stops the PLC, Non-Fatal never
stops the PLC and Conditionally Fatal stops the PLC depending on other information in the fault.
Note that Non-Fatal and Diagnostic have the same meaning.
Not Synchronized
FaultAct
i
on
Fault Group Table
Type Description Default Configurable
Synchronized
Fault Action
(fixed)
LOSS_RACK PLC Loss of or Missing Rack Non-Fatal Yes Fatal
LOSS_IOC I/O Loss of or Missing IOC Non-Fatal Yes * Fatal
LOSS_IO_MOD I/O Loss of or Missing I/O Module Non-Fatal Yes Non-Fatal
LOSS_OTHR_MOD PLC Loss of or Missing Option Module Non-Fatal Yes Non-Fatal
SYS_BUS_ERROR PLC System Bus Error Fatal Yes Fatal
IOC_FAULT I/O IOC or I/O Bus Fault Non-Fatal Yes Conditi onally Fatal
CNFG_MIS_MTCH Both System Configuration Mismatch Fatal Yes Non-Fatal
IOC_SOFTWR I/O IO C Software Failure Fatal Uses LOSS_IO C
setting Conditionally Fata l
The two fault groups IOC_FAULT and IOC_SOFTWR faults are fatal to the system (force the
PLC to STOP FAULT mode) if the fault is Fatal to the Genius Bus Controller that logged the fault.
When a module logs a fault it notifies the PLC whether or not it can continue by placing Fatal or
Diagnostic in the fault action of the fault entry. The PLC shuts the Genius Bus Controller down on
all Fatal faults.

*

Even if the LOSS_IOC fault is configured as Fatal for non-synchronized operation, the PLC will not go to
STOP/FAULT mode unless both Genius Bus Controllers of a dual bus pair fail.