ControlLogix 1756-L62 - Causing BackPlane Communication Issues

Good Morning ,


We had our 2nd episode in 4 weeks with a 1756-L62 processor causing a backplane communication issue , that caused us to lose communication to our Sercos , input and output modules. We changed the Power Supply , Backplane ,etc.


Even powering the rack down and back up , never restored the communication. The CPU never showed a fault.


Been speaking with Rockwell and they sent me Technical Note ID 41204 , about a noise issue in a number of 1756 modules manufactured from September 2006 thru June 2007.In the technical note they refered to a ASIC component . If it had ATMEL stamped on the component it was a possible module that had that potential to fail due to noise issues.


When it fails , the following slots show the following....


Power Supply - Good
Slot 0 - 1756-L61 Good
Slot 1 - 1756-ENBT Good
Slot 2 - 1756-M16SE Faulted ( This does say ATMEL but
not the correct number )
Slot 3 - 1756-IB32 Faulted
Slot 4 - 1756-OB32 Faulted
Slot 5 - 1756-IB16 Faulted
Slot 6 - 1756-OF 8 Faulted
Slot 7 - 1756-OF 8 Faulted
Slot 8 - 1756-IR6I Faulted
RS Linx only sees the Processor and 1756-ENBT module.


Have you guys ever seen this before ?


Thanks so much for your help.

What size power supply (part number)?

The opening statement says L62 but later you say L61?

I'm sorry. 1756-L62
Power Supply 1756-PB72

Remove all module but the CPU. Then install them one at a time.

OG

Why do we need to keep doing this ? The definition of insanity it seems LOL

There was another thread a couple of weeks ago with similar symptoms; 1756-L6x, SERCOS module, all other modules faulted. I checked Cydog's post history and it doesn't appear to be him, so I guess it's just coincidence.

"Why do I have to keep troubleshooting" is a bit of a rhetorical question. You need to keep troubleshooting because you haven't found the problem, haven't fixed the problem, or there is more than one problem.

I sympathize, I really do. But you've got to use basic process of elimination.

If the CPU isn't the problem, and the backplane isn't the problem, and this has run for a decade without exhibiting the problem... then it's probably the 1756 SERCOS module.

The SERCOS modules, like CPUs and network modules, have a more sophisticated backplane interface than the I/O modules do. If their backplane chip malfunctions it can prevent modules other than itself from communicating with the CPU or Ethernet.

Thanks . It is actually a new SERCOS module.

Were you able to identify the problem and have a solution?