program wiped from SLC5/01

Recently, the program was wiped from the PLC controlling our frozen storage compressor/evaporator/condenser system. We didnt have a copy because we relied on a third-party for service. frankly, the manager wasn't even aware that there was a PLC in the control cabinet.

Third-party shut off the power in the morning, changed oil and did other PMs throughout the day, then swapped a new 1747-OW16 for an old one with a bad relay. Upon powering back up, program was erased. I'm guessing the battery was bad and it was shut down long enough to lose the program. The service provider says they were sold the wrong version of the OW16, it faulted, then it wiped the program.

My question is... What it the most likely cause of program loss - my scenario or theirs?

Your scenario. An incorrect card or a bad card will fault the processor but usually not corrupt the memory. The SLCs will usually hold the program for many minutes even without the battery. There is a capacitor that holds the memory while you cahnge the battery.

If the battery is low you should have had a low battery status led on. See picture.

Power surges can cause the program to be wiped. Along with no surge protection on inductive loads.

something doesn't quite add up here ...

the chart show below is from page 43 of the following manual ...

http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1747-um011_-en-p.pdf

so – according to the book, even without a battery at all, an SLC-5/01 should have retained the memory for quite a long time ... ("long" as in DAYS) ...

just guessing: MAYBE there is a battery installed – but MAYBE the battery is stone cold dead – so MAYBE the battery is shorting out the capacitor and MAYBE that caused the program to dump ...

then again, are you absolutely SURE that the program is actually gone? ... what type of indications do you get when you try to go online with the processor? ...

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and while we're on the subject ...

and just a word of friendly advice – mostly to other readers who might pass this way in the future ...

We didn't have a copy because we relied on a third-party for service.

Click to expand...

no matter whom you rely upon for service, it's always a good idea to have a backup copy of your own "just in case" ...

I realize that having a copy is a good idea. However, the PLC isn't in my facility and the manager didn't realize there was a PLC in the control panel. We do have back-ups of programs in things such as pallet wrapper at the facility.

I know the program was wiped because I checked it myself when they realized they had a problem. I could go on-line, but there was no program.

Apparently, the control panel was built about 22 years ago. According to those I've spoken to who have been here that long, this panel has never been worked on.

Thanks for the replies.

somehow we're not exactly in sync here ...

I could go on-line, but there was no program.

Click to expand...

as far as I know, the basic idea is that you can't "go online" (communicate) with a processor that has no program ...

the figure below was taken when trying to go ONLINE with a "blank – no program" processor ... I was using an SLC-5/04 (not an SLC-5/01) but I've got a hunch you'd see the same thing with the smaller system ...

so ...

can you get us a couple of screen shots of what you're seeing? ...

naturally I'm just guessing based on what you've been able to tell us so far – but I've still got a hunch that the program MIGHT (just MIGHT) still be in the processor ...

quick questions:

(1) is it possible that you're saying there is "no program" in the processor – when what you mean to say is that "there are no RUNGS present in the existing program" instead? ...

(2) did the service company actually hook up a computer to the processor? ... just a guess – but maybe when they were trying to "set up" and install the new module – they inadvertently downloaded a "blank" program which had no rungs? ...

(3) is there an EEPROM installed that perhaps dumped in a "blank" program? ...

(4) how are you planning to get back in operation? ... is someone rewriting the program from scratch? ... maybe there's a printout in the cabinet's documentation pocket – or in some moldy old manual on a dusty shelf somewhere ...

good luck with your project ...

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Without researching, I have never heard of any problems or firmware updates with one of hte most common cards ever sold for a SLC. Any number of things can wipe the SLC code. There are multiple choices for getting a backup and keeping it readily available.

They were blowing smoke up your booty with the OW16 comment, perhaps it is a wild guess....maybe the card was not fully seated and left a slot fault code behind that lead to their speculation. In any case, they should know better than to shutdown a SLC for maintenance without checking the BATT light and having a backup available, so I think the blame rests heavily on this 3rd party in this particular case...going forward, have them leave you a copy of the RSLogix500 project, and a battery maintenance schedule at least. Some applications (Logix500 software and/or skills unavailable) call for a memory module although I don't like the tradeoffs...

I have seen this twice before on a PLC 5. You go online and there is no program. The second time this happened was when someone tried to hot swap a Control net card on the rack once. It wiped out the program.