Emerson Exchange 365

We are facing problem that both redundant profibus cards (C55 & C56) of PCU-I at our plant are showing error (PStatus:Pair Status:Both Cards report Problem) as shown in the following screen shots. Due to this problem profibus fault is occurring frequently and it acknowledges when plant operator reset the fault.

We have adopted following line of action but problem still persists.

1. Checked the completed profibus cable loop and found ok.
2. Swapped the both redundant profibus cards of PCU-I with redundant profibus cards of PCU-III but problem still persists. The (problematic) profibus cards which were removed from PCU-I and installed at PCU-III are showing good status and no error shown there while the healthy profibus cards which were removed from PCU-III and installed at PCU-I are showing the same error “(PStatus:Pair Status:Both Cards report Problem)”.

Can any one have idea how to resolve this issue.(Urgent)