ControlLogix 5500 Losing Program

I have a 10+ year old ControlLogix that has been losing its program on a regular basis (twice a week, roughly). It claims the battery is fine (it is replaced regularly). The ethernet module is holding its IP and all the IO seems to be fine. No documented power issues.

Anything I can check before I replace the unit?

Thanks.

I remember the first one I had... it would eat a battery over the weekend so I ended up running a dedicated PS to the CPU but never lost the program under normal conditions, I would look at upgrading to a 1756-L6x you can get a used one cheap enough and should solve your issue

Several thoughts come to mind.

power supply going bad.
bad rack
cpu going bad.

I would reseat and reconnect all the components, connections may be getting corroded/dirty.

if you have a voltage sag, the cpu could go into shutdown mode.
as its going into shutdown mode, the voltage is restored and the cpu tries to restart as its shutting down. I have had this issue several times on a slc 500/plc5.

install a surge suppressor in front of the plc to see if that fixes the issue.
since we had this first issue, we put surge suppressors on all our equipment.
we use corcom 10vwxx series and have had no issues. Note: I am not connected to corcom and get no pay for endorsing their product.

james.

kmayreis said:

I have a 10+ year old ControlLogix that has been losing its program on a regular basis (twice a week, roughly). It claims the battery is fine (it is replaced regularly). The ethernet module is holding its IP and all the IO seems to be fine. No documented power issues.

Anything I can check before I replace the unit?

Thanks.

Click to expand...

Hi, L55? you know which firmware?

I see there is a product service advisory, Product Service Advisory— Power
Disruptions Cleared Memory

Firmware is old. Version 4.3.2, but I have 7 others running the same firmware for the same length of time and they are all fine.

I am going to re-seat all the cards in the chassis and see if that helps. In the meantime, I'm shopping for spare parts.

Thanks for the suggestions everyone!

reseat and upgrade firmware is my choice to v17, I believe it's max for L55

I misspoke on the Firmware. It's version 16.0.x (can't recall the rest). It looks like the Ethernet module is what's on version 4.3.2.

I reseated the PLC in the same Slot - Slot 0. It errored, I couldn't download to it. I moved it to the next open slot - Slot 4 - and I was able to connect, download the program, and then it went belly-up again about 2 minutes later.

I've got a spare power supply, spare chassis, and new 1756-L71 on the way.

Thanks again everyone.

I swapped the power supply. No change.

I swapped the chassis. Was able to download the program after clearing a "major fault" (Code 60). Left the PLC in Rem Prog mode to see if it would stay functional. It did not. Faulted again (same error lights) after about 5 minutes.

I have a 1756-L71 but it appears to not be compatible with my version of RSLogix 5000 (16.0.0).

Can anyone confirm that I am going to need to update Logix 5000 to get this thing online? When I choose "Change Controller" in the program, the L71 is not an option. It's obviously too new, but are there EDS files or anything that would allow me to use this version of Logix?

Thanks!

I think you need 20 or later, do you have a Tech Connect? if so you can download it

L71 requires ver. 20 or greater. An L61 can go from ver. 13 to version 20.

When you had the PLC in program mode and it faulted, what was the fault code?

Error 60 could explain the program loss. Are you using IOT (immediate output) commands in the program?

@Andy6 - When it faults it disconnects and the indicator lights (Run and OK) turn solid red. I previously would cycle power and it would clear the issue (no fault on next connect) but the PLC would dump its program. This happened 3 or 4 times over the course of a month and now it fails in 5 minutes instead of 5+ days. As for IOTs, it's not my program and I'm a novice programmer at best, so I'm not certain but I don't believe there are any. This PLC had been running without incident for the last 10+ years. No changes to the program of late other than an IP change of the Ethernet module and communication path changes on some PLC to PLC messaging. Also, the first occurrence of this was prior to any changes in the program, so I think it's just hardware failure. Unfortunately, it doesn't seem to be the chassis or the power supply since the issue persisted after each was replaced. I need a new version of Logix5000 to communicate with the new PLC. It's tough working on all this vintage stuff!

I did an installation nearly 10 years ago where we had this problem with version 16 firmware 1756-L55 ControlLogix PLC's. Certain plc's would periodically clear the memory to protect themselves after detecting a fault. After a lot of searching for info and speaking to Rockwell I'm sure it was resolved by installing some patch coding which after looking at it again must have been provided by Rockwell.

How long has this been in service? I installed a L61 in 2008 that had similar issues. There was a batch of L61's with a defective chip on board that caused the issue.
Back then I:

Called RA support. The controller has a bad Atmel chip, and had to be replaced. If you look down inside the module ( from the top) , you can see the Atmel chip, it's about 1 inch square, if the second line of numbers ends in 64, you may eventually have the same issue, if your chip ends in 65, you're okay.

beethoven_ii said:

I did an installation nearly 10 years ago where we had this problem with version 16 firmware 1756-L55 ControlLogix PLC's. Certain plc's would periodically clear the memory to protect themselves after detecting a fault. After a lot of searching for info and speaking to Rockwell I'm sure it was resolved by installing some patch coding which after looking at it again must have been provided by Rockwell.

Click to expand...

If it's the same PSA I'm thinking of, it was actually at firmware revision 15.03 or 15.04. Flash upgrading to firmware revision 15.05 resolved the issue.

Until the flash could be performed, Rockwell provided a temporary patch to prevent the controller diagnostics check on the firmware image after it is loaded from flash into RAM. I think this is what you are referring to? It was to be only executed once during first scan...

(See "Prevention" - Option "3.")

35190 - 1756-L55 and 1794-L34 Controllers at revision 15 firmware can generate a non-recoverable major fault and lose memory
Access Level: TechConnect

If the 1756-L55 in question here is at firmware revision 16 then I don't think that PSA is the likely cause here?

Ken Moore said:

...There was a batch of L61's with a defective chip on board that caused the issue...

...The controller has a bad Atmel chip, and had to be replaced. If you look down inside the module ( from the top) , you can see the Atmel chip, it's about 1 inch square, if the second line of numbers ends in 64, you may eventually have the same issue...

Click to expand...

Ken,

I believe this is the PSA you are referring to and it affects many different products, including the L55 & L61...

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

"Rockwell Automation manufactured the affected Logix products from October 2006 through March 2007"

kmayreis,

If your L55 falls with that production period then I would also recommend you check, as Ken has advised, for the presence of an Atmel chip and serial number ending in 64.

Regards,
George