1769 -L32E Program Lost

Have two seperate locations where the program was lost on a 1769-L32E after a power on/off. Battery was check and is good. Both systems newly installed within the last year.

That can happen with power surges. Also if you have inductive loads without surge protection.
Make sure you have grounded everything properly.

I’ve not come across this with a CompactLogix but I have with MicroLogix. It doesn’t take much to dump the program and I’d guess it’s by design. If the PLC/PAC is controlling equipment that could cause harm and there is a power surge or a short I’d feel better if the PLC/PAC could no longer control anything until I intervened. A simple reset would be nice but I could also argue that anything short of dumping the program leaves room for something bad to happen. It’s just a guess but again it takes very little to get a MicroLogix (or SLC for that matter) to dump its program. Having said that I’ve never seen it happen when there was nothing but a power cycle so I’d guess that when the power came back on (or when it went off) that there was a surge. That’s actually a good argument for using 24VDC controller with a good solid power supply. Having said that, a good UPS should also work.

I have had this happed several times.

Dead battery - once or twice
Brown out conditions - multiple times with a plc5 - even with a new battery.
it has to do with the shutdown / power up sequence happening at the same time.
Slc 500 - brown outs - twice in a week.
Installed a corcom surge suppressor and the plc has not faulted since.
It's now standard equipment on all panels I buy/ design / build.

Costs to install it, but well worth it when you don't get the call at 2 am saying the plc died and you have to drive 250 miles one way to reset the unit.

james

I've had this happen numerous times on L32's under sudden power loss/power up conditions. It's one of those 'features' Allen Bradley installs to make our lives easier.

The easiest way to deal with it is to put the program on an SD card and set the load image to 'On Corrupt Memory' and the load mode to 'Run'. Your other option is probably a UPS.

The memory card is a great idea however even if that solves the problem the fact that you have a PAC that is being subjected to sudden power cycles screams UPS. If the power cycle is rapid chances are pretty good that you’re getting a spike and that’s going to do damage over time.

I had this happen to an L33ER last month. It's not always due to poor power quality either. In my case it was an operator cycling power like a crazy person.

Jeev said:

I had this happen to an L33ER last month. It's not always due to poor power quality either. In my case it was an operator cycling power like a crazy person.

Click to expand...

"Have you tried turning it off and on again?"
"Yes. Forty times in fact. Since that start of this phone call."

Hello. In one instance there was a known power outage and then surge. At the other location the conditions are not exactly known other than 3 seperate controllers, 2 in one cabinet & 1 in another, all of which were missing the program when I arrived. Both sites are looking into installing a UPS.
The programs were created in ver 16. I have found several known anomalies published by AB where under certain sudden power changes can corrupt the program. These issues were supposed to be resolved in later versions.

I just had a L32E with rev 20 lose the program. It is on a 24VDC power supply with a battery bank.

All four channels on an 1769-IF4I would only read 32767 after an alleged lightning strike and the operators attempted to remove the module from the 'backplane', but the 1769 all snaps together and the module was in between the CPU and the power supply so the CPU probably had the power rapidly cycled many times as they tried to pull the module out but couldn't since it was attached to the two modules beside it.

The battery OK light is off in RSLogix5000, which is kind of confusing. is it OK or not? it should be green like the IO OK light if it is OK. When I click the Battery checkbox in the minor faults tab of the CPU the Battery OK light in RSlogix5000 briefly goes red. The battery light is OFF on the front of the CPU and the manual indicates it would be red if there was a problem.

So the 1769-L32E lost the program with an OK battery. Will wait and see if it loses it again when the PLC is powered off to replace the faulty 1769-IF4I.