I have a series six unit that is faulting. The CPU is going into going into stop and will stay there until the run/stop key switch is toggled.

I have replaced all the cards in the CPU rack including the memory & power supply. The problem has settled down but is still occurring once every 24 to 48 hours!

Once the CPU could be access by the programmer and the following was reported:

CPU Error Flags: 11110100 01000011 10010001 00000000
IO Status Table Parity Error:0043

The series six fault documentation is a little thin in the description on this error?

Can anybody elaborate on this fault for me or have any other suggestions?

Bad connections between the modules and the backplane are often the source of intermittent faults. Sometimes removing/inserting the modules several times will wipe the connections clean and make the problem go away.

Use the insertion/removal tool to push the modules into place. If you find that you don't need the tool to remove a module, it means you don't have as tight a connection as you should. In that case, replace the rack.