Why does my PCS1 get a "68k Error" and does run again after a power cycle?

FAQ #100286

 

Symptom
An application running on a PCS with hardware version older than D is running fine but in some cases the PCS1 goes to Halt and indicates e.g. a "68k Error" or "Invalid OPC" errors. The error messages are not always the same.
After restarting the PCS (e.g. with a power down / power up) the PCS1 is running fine again.

Possible reason
Some of the digital outputs of the PCS1 are relay outputs. On some applications the PCS1 experiences errors such as "68k Errors" or "Invalid OPC" because inductive charges (other relays for instance) were switched with the mentioned relay outputs. 
With HW version D additional improvements were introduced to make the PCS1 less sensitive against such perturbations, but even the early CPU's (e.g. hardware version A) that left the company were conform to the EMC statements.

Solution
The corrective action is to add RC or other filters on the inductive charges, to reduce the high voltage peaks that occur if the supply of an inductive charge is cut. The best place to place the filters is directly on the source, many relay manufacturers offer optional RC cirquits that can easily be mounted.