ControlLogix 1756-L60M03SE NVM

bigsteve777

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Dec 2013
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What could be the possible cause of the Non-Volatile Memory (NVM) being erased from this processor? I have 8 alike machines with this processor. I've loaded the NVM with the program and have the key switch in the RUN position so it will load from the NVM after a power down situation. 4 of the machines have lost the program in the NVM. In checking the processor faults of these not working machines all had a Type 07 Code 41 fault then I noticed there was no program in the NVM.

Thanks for your help.

Bigsteve777
 
Type 7 Code 41 is a failed read from the removable memory card, and in the case of these older 1756-L6x controllers that's a CompactFlash card.

Failures across four different controllers strongly suggests damaged, defective, or incompatible flash cards, or an incorrect or corrupted controller image file on the cards.

Do you have the A-B branded CF cards, or an industrial or commercial vendor card installed ? Is your application writing to the CF cards regularly ?
 
Or... take a step back....

When a ControlLogix controller encounters a corrupted user program in RAM, it intentionally erases the program in RAM. This is normal behavior but it is often referred to as the controller "losing" the program.

When a ControlLogix encounters a corrupted or invalid controller memory image on the CompactFlash or Secure Digital removable memory device, it cannot load and run that program, so it sets the Type 7 Code 41 fault.

But (to my knowledge) it doesn't attempt to erase or modify the file on the CF/SD card.

So if your examination of the CF card shows an empty directory, it's very likely that it was not there prior to the load-on-powerup event. Have you put the CF card into a card reader and read it with a computer, or are you looking only at the RSLogix 5000 Nonvolatile Memory window and seeing a "no image on card" message ?

Some of the issue may depend on how the image file was created. If it was written from a file archive by a computer, maybe it was corrupted in the process. If it was created by the 1756-L60 itself in a "Store to NV" process, then the card failed to properly create the file, suggesting a hardware, format, or file system problem.

It's really good that you're testing this functionality. Failure to test Restore after Backup, in all sorts of computer system contexts, is a classic blunder.
 
Hi guys! Thanks for your replies. I did also contact Rockwell via online chat and he gave me pretty much the same info saying it was the card. I personally loaded all NVM on these machines myself and they are AB cards. We started doing this because upon power downs over the weekend/shutdowns some batteries would fail and loose power from the RAM so I'd end up loading programs on Monday. After loading the NVM and choosing to "load on powerup" this problem went away until the last couple of months. I have reloaded the NVM and will wait again an see if this happens again and then pull the card and try and read it in a reader.

Thanks again!
 

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