CompactLogic lost program

We have some AB CompactLogix PLCs running a coal/dirt separating plant. When an operator when to crank the plant this morning there was no comm between computer & PLC... complete comm loss. Upon further investigation it was found that the program had just disappeared out of the PLC... I saw where there was a known issue with a specific firmware version losing the program on an i/o fault/power cycle situation but wondering if anyone else has seen this problem? A copy of the program was downloaded back to the PLC and everything was fine... What say ye?

Does the PLC have a battery backup or use a compact flash card? If you had power loss and the battery was dead it would lose the program. Just a thought.

Tech4man www.tech4.com

Tech4man said:

Does the PLC have a battery backup or use a compact flash card? If you had power loss and the battery was dead it would lose the program. Just a thought.

Tech4man www.tech4.com

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Yes, good thought... unfortunately the night crew said there wasnt a power loss doesn't sound like we have all the pieces to the puzzle does it? lol

txmudslinger said:

Yes, good thought... unfortunately the night crew said there wasnt a power loss doesn't sound like we have all the pieces to the puzzle does it? lol

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Not just power loss but power spikes will whipe out the program or part of it from the PLC.
We had same issues with Compact Logix series controllers.
Surge protection/filtering will resolve most of your issues.

Also if it is running on a generator and the genny is shut down without the circuit breaker being switched off first, you can guarentee the program will be wiped.
Regards Alan

never underestimate the ability of an operator to screw things up.

over the weekend a stopped up float switch on a compressor turned into a "PLC" problem that required the operator to somehow clear the PLC memory. I always love that.