Allen Bradley PLC5/40 PROC light alternating red green

[shanefaulkner]

Today I was making an online edit to a 5/40 Series E Rev K.2 with about 14% free memory. I was removing one branch in a large rung. Accept edits, test edits worked fine. I went to assemble edits, and got an error message "Assemble edits failed" and... something happened to the PLC. Logix5 got disconnected and the PLC stopped working.

The PROC light was alternating between red and green. The documentation says this indicates "Processor FLASH memory checksum error - contact your local A-B rep for a field firmware update".

I tried to wipe its program, removed battery then powered back up. Tried switching key from PROG back to REM. It still is alternating red and green and I cannot get back online.

Has anyone ever seen such behavior? I know you can run into problems when editing a large rung with very little free memory (not sure what this can cause, I just know to try to avoid it), but I thought 14% free would be more than enough. Luckily the plant had a shelf spare (a larger 5/60). I just can't fathom how editing a rung would brick a processor like this.

 

[I_Automation]

I never made a firmware error, but did find out the hard way about full memory.


When I accepted an online edit I got an error sometimes, but other online edits worked fine. When I went back online after being kicked off the rung I was editing was completely gone - no original or edit.



Went offline and made the edits there and when I verified got the out of memory popup, but never got that online. This PLC5/30 had 64 words of unused memory in it, and an online edit makes a copy of the rung and if it's over that 64 then WHAMMO.


Honestly I don't see how any online edit could cause a firmware fault though.

 

[shanefaulkner]

Thanks I_A for the confirmation about what can happen when making online edits with very little free memory. I will certainly continue to try to avoid that in the future.

As much as I love being a trailblazer, I thought for sure one of the grizzled vets on this site would have seen this before, but I guess not! I suppose it's possible that this PLC's circuits decided to get fried at the exact moment I assembled an online edit, and it was all coincidental and unrelated.

 

[I_Automation]

I would suggest eBay for this.

To get a PLC5 CPU from Rockwell you have to fill out an
application now, and if approved a new CPU last time I
checked was a cool $35,000.

They really want you to upgrade to a ControlLogix

 

[JTCat]

You need to flash the firmware. It's not hard. I've done it a dozen or more times.
How it got into flash programming mode, that's the mystery.
Quick edit - if you don't have access to the flash software and firmware then you aren't likely to get it. Rockwell stopped making it available a long time ago.
You could get lucky if an integrator nearby has one, but don't expect the service to be cheap.

https://literature.rockwellautomation.com/idc/groups/literature/documents/um/1785-um002_-en-p.pdf