ContolLogix Lost the Program

I have a 1756-L55/A, Rev. 11.25 that lost it's program while running. When I got to the panel, the BAT LED was dark and the OK LED was solid red. When I tried to go online with it, there was no program in the PLC. I downloaded and power cycled and sure enough, no program, BAT LED not lit. I replaced the battery, downloaded and power cycled, no problem. Power cycled like 8 more times, no problem. Returned the system to production and it has been running like 20 hours now.

Any clues as to why this can happen or advice on how to prevent geriatric controllers from arriving at complete dementia would be greatly appreciated.

Of course we are planning and allocating to replace grandpa with a new baby L62, but that could take a little while.

Could this be an ATMEL chip issue? is this the first time it's happened?

What is an ATMEL chip issue and how could I determince it is such and issue?

40149 - Service Advisory - ControlLogix and CompactLogix products - Modules shut down due to erroneous data (200705002)


Access Level: Everyone
Date Created: 05/25/2007 10:00 PM
Last Updated: 07/05/2012 12:28 PM

41204 - ControlLogix - Communications Lock Up


Access Level: Everyone
Date Created: 07/25/2007 02:12 PM
Last Updated: 01/11/2013 09:24 PM

You replaced the battery and it works now. End of story. If the battery was dead, all it takes is a power blip and your program is gone. If your 1756-L55 is continuously powered up, the battery should last up to 3 years. If you power it off on weekends, considerably less.

The battery LED on a ControlLogix is solid red if the battery is low or missing, but it is off when the battery is good.

So the battery LED being off means the controller should have held its program through a power cycle.

If this is the only incident in the controller's lifetime, this is very unlikely to be a controller bug or a chipset defect.

If it were mine, I would inspect the panel for decent grounds, maybe add an AC filter, and continue running.

I run into a similar issue with 1756-L55 rev. 16. There is a tech note on AB Kb saying that the PLC with firmware 16.020 or less will loose the program if runs 60 - 90 days continuously, without cycling power. Solution is to put the latest firmware that fixes this issue (16.021) or to cycle power once a month. This note applies only to firmware rev. 16.
CoS

Yup, I know Ken.
But he said...

"I downloaded and power cycled and sure enough, no program, BAT LED not lit. I replaced the battery, downloaded and power cycled, no problem. Power cycled like 8 more times, no problem."

Sure seems like changing the battery was the key to making it work. Perhaps the BAT LED has failed? Easy enough to test, just unplug the battery.

That being said, bad grounding, and power spikes can corrupt the memory and cause it to dump the program.

But that statement "I downloaded and power cycled and sure enough, no program" bothers me. I can't explain how downloading didn't work until after he changed the battery. Perhaps if I were there and saw exactly what he did, I would have an answer. As it stands, I'm baffled.

43553 - 1756-L55 and 1794-L34 Controllers at certain V16 revisions will nonrecoverable
major fault and lose memory

CoS

Grounding

I agree with Ken,

Properly Ground your Rack! I Have seen the same problem. After being informed on new job site of a processor intermediately losing it's program. I investigated the PLC only to find no Grounding connected to the ground stud on the Rack. I Had Maintenance install ground wire and no issues for 2 years plus.