plc maintenance

can anyone tell me how you go about performing maintenance checks and otherwise servicing plc's that operate with servers.
thanks for any information

There aren't too many things on a PLC that you can do any preventive maintenance on. If your model has one, you can change the battery on a regular basis. If you have analog inputs and outputs, you might be able to calibrate them periodically, although not all brands have published field calibration procedures. Make sure that dust is not building up on circuit boards. Change the filters in the enclosure that houses the PLC. Make sure there is clear path for airflow around the PLC. If your system has a hot standby PLC, you can switch over to the backup periodically to make sure that it works and that the transition is bumpless.

More often, you need to check the devices wired to the PLC for proper function and visible signs of wear. If there are devices that only operate infrequently, or in emergencies, you should periodically make sure they're still functional.

It's a lot more work, but you can compile a table of performance specs and periodically compare actual performance to the baseline data. For example, your baseline performance could include the elapsed time between energizing a hydraulic solenoid valve and the completion of the associated motion. If you detect a significant variance from that time, you start looking for what might cause it.

Could you clarify what you mean by "plc's that operate with servers"?

plc maintenance continued

Steve thanks for all the information. the servers referred to are those associated with scada systems

One thing to consider is a validation program. Verify that what
you have as a backup program is the same as what is running
in the field. You may be surprised at what you find.
Since you mentioned SCADA, you may want to make a ghost image
of your PC's, this could save some time in the event of a crash.

Agreed, JDW. What a nightmare I walked into in my last job concerning valid backups (actually, lack thereof) for the 80+ plc's in the facility. No one knew where the latest ones were or even if one existed at all. Immediately, I started an official, crack-your-knuckles-if-you-don't-conform policy to maintain backup copies. It's never too late to get your arms around that beast.