CompactLogix failing at random

[matth5468]

We have a new installation using an AB CompactLogix 1769-L35E which has been running for almost a couple of months, and just a few weeks ago it has started failing. The 'OK', 'MS', and 'CF' lights are solid red, we have had no luck communicating with the processor, and after cycling power to the processor we do not have any major or minor faults. The Compactlogix rack consists of the processor, 18 dc input cards (1769-IQ16) and 1 dc output card, seperated just as they should per power requirements using 2 1769-PB4 power supplies, and a 1769-CRLx connector between the banks and a 1769-ECR on the end. Aside from installing all new everything we have almost exhausted our search for a problem.
We have tried:
New processor
New power supplies
New supplies feeding the PB4
updating the firmware
changing the input cards between the supply and the processor
We have watched power coming into the supply while it fails and have seen no problems with it

Our company has an identical setup in another location that has not failed yet, which leads me to think it is a hardware problem.

please help me

..matt

 

[ATenorioB]

If you have access to the other PLC try to switch them (if you have that option) and check if it works properly at the other location. In case it does, try checking for EM noise and mechanical vibrations if you are in a heavy industrial environment. Otherwise contact the vendor or manufacturer to see if the warranty applies to your kind of problem, and by the looks of it it probably does.

Good luck.
-Agustín

 

[matth5468]

The other location is hundereds of miles away and we would rather not interupt their operation at all. No noticable noise, and vibrations are limited. Yes some warranty applies, but the problem has come back after replacing the right end cap, moving the power supply even closer, and jumping ground to DC- the problem went away for two days, but it is back.

..matt