Fault 5h (Retentive data is lost)

I am getting a Fault 5h (retentive data is lost) on a ML1000 PLC

I clear the fault, and it comes back.. I don't really understand what the fault is, so its hard to fix it.


In the mean-time, I cleared the proc, re-uploaded the program.. Fault is still there.

Re-wrote the Ladder from scratch, and cleared the mem, re-uploaded, Fault is gone, but I need to verify that I didn't lose anything else important.

Any ideas? Is there anything important other than the ladder logic, node, and proc name? Everything seems to be working, but this is a very important project, and I want to make sure I didn't screw anything up.

for this you need clear another bit post the screen Image since i don't have a RSL500 software

There are status bits that will still be set to 1. If the error returns, clear the error and them look to see if there are any 1's in the status file bits.



Hope this helps.

If this happened to you once, it will likely happen again. We had a few of the Micrologix 1000 processors with this problem. Apparently, according to A-B there was a run of these that had this problem and the only way to fix it is to replace the processor. Our problem would happen intermittingly, sometimes once a month, sometimes every couple of months. We at first thought we were getting power spikes and installed filters, but this didn't help. Again, the final fix was to replace the processor.

Also, if this happens again, the "retentive data lost bit" will be set to 1. You'll have to toggle that bit to zero and then reset the fault. You won't have to reload the program, just put the processor in run mode.

From Rockwell knowledgebase see doc below:

Error code 5h means your program is corrupted and no longer usable by the processor. This can be caused by not having spike protection on the outputs as well as the power supply (happened to me), installed the spike protection and the problem went away. If by mistake when you got on line with the faulted processor you did an upload (moved the program from the ML1000 to the laptop)and did a save, you saved the corrupted program and the fault to the laptop memory. A download to the processor would have put the problem right back into the ML1000. The problem with the ML1000 locking up with the fault light on solid also happened to me twice. As long as the fault LED is solid can can do nothing with the unit, no upload, no download, no going on line. Sometimes dropping and reapplying power will get the fault light flashing, then you can go on line, but the ML1000 is probably one of the ones rockwell says has a problem with the SRAM.

Thanks everyone for the help. I will prepare a spare ML1000 incase this happens again.