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.
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...
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