Rockwell Automation 1785-Vx0B, D17856.5.9 PLC-5 VME VMEbus Programmable Controllers User Manual - Manual (Page 255)

Appendix D
Troubleshooting
D-6
ATTENTION: Processor memory could become altered without
indication if you lose power while performing any of the
following online editing operations:
creating a rung
assembling online edits
creating and/or deleting data table space
If you lose power while editing your program, use your programming
software package to clear potentially altered memory and restore the
last-saved version of your program.
12.
Fault routines execute when a PLC-5 processor encounters a run-time error
(major fault) during program execution.
13.
A fault routine processes the major fault bit found in S:11 and determines
the course of program execution based on the fault bit present. Fault
routines provide a means to either:
systematically shut down a process or control operation
log and clear the fault and continue normal operation
ATTENTION: Clearing a major fault does not correct the cause
of the fault. Be sure to examine the fault bit and correct the cause
of the fault before clearing it.
For example, if a major fault is encountered, causing bit S:11/2
to be set, which indicates a programming error, do not use a
fault routine to clear the fault until you correct your program.
For more information about fault codes, see your programming software
documentation set.
To avoid encountering a possible run-time error when executing FBC and
DDT instructions, add a ladder rung that clears S:24 (indexed addressing
offset) immediately before a FBC or DDT instruction.
14.
Recovering from Possible
Memory Corruption
Examining Fault Codes
Avoiding Run-time Errors
when Executing FBC and
DDT Instructions