AB 1769 L32E Processor losing program

Hey guys,

I had a troubleshooting callout yesterday to the local WWTP, The local electrician figured it was a DN scanner failure but after further troubleshooting, I determined the "Treatment" processor had dumped Its program. When I first pulled up RSLinx I could see the processor was communicating over the Ethernet network but I noticed that the processor didn't have a name on it nor could I get online with it.

Usually, as you know the processors under the tabs in RSLinx are labelled with the current program, which all the others on the network were beside the treatment PLC processor. So I had to redownload the program onto the processor and of course, everything fired back up. My question is, what causes a processor to just dump a program like that with no power failure or anything alike?

regards,

Tex

Check grounding and make sure you have surge protection on all inductive loads.

Brown outs (flickering lights) and then sudden voltage spikes will do it.
have had it happen several times in a slc and plc5.

install a surge suppressor in front of the plc.

james

Assuming the battery is good, I've had frequency drives with too short an accel / decel ramp corrupt a processor. Line would go down, "Default" (empty) program would be in the processor. Panel had about 30 drives, the mechanics decided it would be a great idea to set some ramps to .1 seconds from 5.0 seconds. They were high inertia fans with impellers weghing ten pounds or so. Set things back to 5.0 seconds problem never happened again.

Any "Non-Recoverable Major Fault" will result in the processor dumping its program, it's a safeguard against trying to run with a corrupted program or data or a hardware fault.

Diagnostic Information on the fault condition is written to a CF or SD card, if one is installed. This information can be used to determine what caused the fault. Of course, if the processor has suffered a catastrophic hardware failure, it is possible that the diagnostic info will not be written....

If the processor can be got working again, by downloading the program, then it is likely that there isn't a specific hardware problem with it, and the fault was caused by memory corruption due to noise, either electrical (induced into the wiring), or by strong RF emissions near the processor. I have seen a processor MNRF when a commissioning engineer was working in the panel, and he used his "walki-talkie"

You need to check compliance with all of the installation guidelines for the processor and its chassis, wiring guidelines, grounding etc. etc.

A very common culprit is the electrical noise generated by variable frequency drives, so cable runs should be as isolated as much as possible from I/O cables. If you have to cross an I/O cable with a drive/motor cable, do it at right-angles to minimise cross-talk