Allen-Bradley SLC 500 Fault Routine

Allen-Bradley SLC 500 controllers allow you to designate a subroutine file as a fault routine. If used, it determines how the processor responds to a programming error. The program file assigned as the fault routine is determined by the value stored in word S:29 of the status file. Entering a 0 in word S:29 disables the fault routine.

There are two kinds of major faults that result in a processor fault: recoverable and nonrecoverable faults. When the processor detects a major fault, it looks for a fault routine.

If a fault routine exists, it is executed; if one does not exist, the processor shuts down. When there is a fault routine, and the fault is recoverable, the fault routine is executed. If the fault is nonrecoverable, the fault routine is scanned once and shuts down. Either way, the fault routine allows for an orderly shutdown.