Micrologix retinative data lost

I have a number of machines with the Micrologix 1000 1761-L16AWA processors on them. Once in a while I get a fault that indicates "Retenative Data Lost", S:5/8. I clear the fault and it works. I don't have any retenative timers or counters in the programming. I have (in the pase) found a loose connection that has caused the ptoblem or missing surge cap on a solenoid or relay, but I have a couple of units I can't find anything wrong with the wiring. After exhausting everyting else, I put an un-latch bit at the end of the program scan to turn this bit off if it is set. Has anyone else tryed this, and can anyone shed anymore light on this? Thanks..
mg

I've never had the fault myself, but found this knowledgebase document:

Retentive Data Lost

Thanks, this looks like my problem but didn't offer any solutions. I even added snubbers across the line power at L1-L2, with no success.
mg

This might help

error code HEX-0005
Fault: retentive data has been lost
Desc: the data files(input, output, timer, counter, integer, binary,
control and status) are corrupted
Recommeded Action: cycle power on your unit
download your program and re-initialize any
necessary data
start up your system

This is something I found on a fault list in an Instruction Set Reference Manual.

Ed

Hi

I had this problem a while ago and I know this sounds wrong
but it was a faulty input.Ever so often the input would go to earth
What I did was check all cables and I found one that was damaged.
I repaired it and this fixed it.I know this sounds very wrong
but it solved it for me.

Donnchadh K.

Micah123,

From the same instruction set reference that ELarsen suggests, the Fault 0002 - Unexpected Reset can cause this as well.

The controller was unexpectedly reset due to a noisy environment or internal hardware failure. If the user program downloaded to the controller is valid, the initial data downloaded with the program is used. The Retentive Data Lost Bit (S:5/8) is set. If the user program is invalid, the default program is loaded.

• Refer to proper grounding guidelines in the MicroLogix 1000 Programmable Controllers User Manual, publication 1761-6.3.
• Contact your local Allen–Bradley representative if the error persists.


Both faults 0002 and 0005 suggest noise on the system and direct you to investigate grounding. I know you said that you went through the wiring and couldn't find anything, but, I think it is worth re-reading the grounding guidelines just in case anything was missed.

If that doesn't show you anything, than I'd contact AB tech support. You may need to replace your processor.

Marc

I also vaguely remember one of my ML1000 faulting a long time ago, and I put a line conditioner on it (Isalatrol 1C105) and never had the problem again. Couldnt hurt

Ed

Had the same problem on a couple of my Micrologix 1000's over 2-3 month period every couple of weeks. Installed a power line filter and haven't had any more problems.

We were having similar problems after installing 10 or so micrologix processors. Every so often, we would get faults on the processors. We talked to the local a-b rep, and it turned out that revision A was subject to these type problems in a "noisy" environment. We put in all revision C's and haven't had any problems since. I don't know what revision micrologix you have, but it may be worth checking.

These are all version "C". At least I know I'm not alone in this..
mg

I'm afraid I have to apologize... When I went out and verified on the machinery, all of our micrologix are version E, so it seems likely that we had version C and upgraded to E....
check this thread out....
http://www.plctalk.net/qanda/showthread.php?s=&threadid=1701&highlight=ground+micro

By the way, I found out this morning that my un-latch for the retenative data lost bit didn't work, still same problem. I'm sure there's a noise problem in the machine somewhere, (very old wiring and difficult to work on). I don't even care if a wire shorts out and blows something up, at least I could find the problem. Anyway, I'll keep trying till I find the problem. Thanks..
mg

In case anyone is interested, I think maybe I should go into fortune telling. This morning an 18MM prox switch exploded, literally blew the housing apart at the seam near the plug. From reading everyones input, it looks like this could have been the problem, maybe arcing inside or something. I hope so anyway. Thanks for everyones input. mg

Are you using the internal 24 VDC to power any of your I/O? If so and this power supply gets shorted out or pulled down it will give you this problem.
I had 2 machines that used ML 1000's and the internal 24VDC was used for push button switches tied to the inputs and 2 prox switches. What was hapening was the contacts in the switches would fail due to water. When the contacts were changed the individule who was changing it out would touch the supply side of the contact block to the metal frame. the PLC would fault out. In my situation it went on for several months. They would call me because of the PLC fault, one day I had reset the fault as they were changing another bad contact and it faulted out. After some playing around I discover that if I shorted the internal 24 VDC it would cause the problem. We installed a seperate 24 VDC for the switches and proxes and have not failed since.

I'm using the 125vac versions of the micrologix 1000. However, the same 125 volts that feed the limit switch is the power for the micrologix. Sounds very similar..