Rockwell Automation 1785-Vx0B, D17856.5.9 PLC-5 VME VMEbus Programmable Controllers User Manual - Manual (Page 254)

Appendix D
Troubleshooting
D-5
If you encounter a hardware error or watchdog major fault, it may be
because multiple watchdog faults occured while the processor was busy
servicing a ladder-related major fault. The hardware error occurs when the
fault queue, which stores a maximum of six faults, becomes full and
cannot store the next fault.
Before calling a service representative when you encounter either a
hardware error or multiple watchdog faults, try executing the
following techniques:
If you encounter a:
Then:
watchdog error
and a fault bit Extend the watchdog timer so that the real run-time error is not masked.
Check your major fault bits. Ignore the watchdog faults and use any
remaining fault bits to help indicate the source of the processor fault.
hardware error 4. Power down; then power up the processor.
5. Reload the program.
6. Set the watchdog timer to a value = 10  current setting
7. Run the program again.
Performing run-time or program-mode editing of ladder files that approach
the maximum program file size of 57,344 words could:
11.
prevent the rung from being inserted
cause suspension of the operation by 6200 Series PLC-5 Programming
Software (release 4.3 and later)
To avoid this problem, segment your program file by using modular
programming design practices, such as main control programs (MCPs),
sequential function charts (SFCs), and the jump to subroutine (JSR)
instruction.
If you cannot segment your program file, save the file often while
editing it.
If you encounter the error “Memory Unavailable for Attempted
Operation” while performing online edits, then use your programming
software package to clear memory and restore the last-saved version of
your program.
Avoiding Multiple
Watchdog Faults
1.
If you continue to encounter
the hardware error, call your
Allen-Bradley representative.
Inserting Ladder Rungs at
the 56K-Word Limit
This consideration applies to
PLC-5/V80 processors when you are
editing a program file that approaches
the maximum file limit of 57,344 words.