Problem in genius bus communication

[kakagi 0]

Dear all,

I'm facing a strange problem in genius bus communication.my system configuration is 90-30 hot redundant (software redundant) CPU372 with two nos of BEM & two no of CMM module in each CPU rack. It has 11 nos of versamax remote IO rack connected with GBI module via BEM with CPU. 

The system was running commissioned and running perfectly for 7 years. Problem started from last month that randomly some or all GBI module stop working. IO enable of GBI change to amber instead if green. Some time only 1 or 2 racks out of 11 and sometimes all the racks. After resetting the power of GBI it again comes back to normal.

I have checked this with both the CPU and it is happening with both the CPU.
As the BEM is redundant so I guess all the BEM are not faulty. Same goes with the cable also.
I also checked the earthing and its okay.
Now I'm clueless. I can't understand why randomly BEM module breaks communication with GBI.

 

[RussB 22]

There is more information on this here:

http://www.plctalk.net/qanda/showthread.php?t=105336

 

Edited 15 Sep 2016 by RussB