plc-5 rack fault


Thread Starter


I have a remote rack on a plc-5 that faults about once a day, and I don't know why. I think that the time slice on the processor is at zero. Could this be the cause of this problem? Is it possible that noise could be causing this problem?

David Ferguson

Comms issue, bad ASB adapter, power supply noise, etc. There are counters in the processor that have diagnostics, under the processor tab in Logix 5.

Do you have a spare adapter, power supply, check cabling. I would probably trade out ASB (set dip switches the same) check all cables and make sure there is not a "hair" of stranded wire touching somewhere else.

Is there a pattern to the time of day that it happens etc..............

Hard to fix from here, hope some of this helps............

Dave Ferguson
Control Systems Engineer
I have seen similar problems. One from noise allowed into the system by timer/counter devices improperly shielded at BOTH ends from device to controls cabinet (contrary to ground-loop theorists who insist otherwise & erroneously). Another place to look is overflow in the registry for time accumulation.