PM891 Fault Mode
Please find the attached pic of hardware configured & Controller settings. When ever I remove Power Supply of primary controller/ Redundant controller, controller is going to fault mode. I am Using Rev C FP4.
Why the RNRP default Network ID is 172.17.0.0, I think it Should be 172.16.0.0
Are you able to get the ping response for 4 ips like 172.16.x.y, 172.17.x.Y ,172.16.x+2.y,172.17.x+2.y.
If everything is proper I feel problem might be the CEX cables, Try by replacing CEX cables.
Hope you set properly redundant CPU's functions by IPConfig tool.
Please check CI854 configuration - I don't know your IO configuration and usage of Profibus processors CI854.
Phisically they are connected to both processors, should be redundant.
But in control builder you don't have configured as redundant?
You could look example in the attached picture - addresses from 1 to 6 are for primary, and addresses from 7 to 12 are for redundant processors.