Redundancy issue

So we have a dual redundant S7-400 with 412-5H CPUs. The problem is they are all running as Masters. We have had issues with the communication to the control system because of data collision, according to one of the CPU's

Diagnostics. We have found duplicated local to remote nodes which is the cause of the collision.

Question is, what controls the operating mode of each CPU Master and Standby modes?

Thank you

...sent from App

Dear S3eed

If you have configured the H System in a proper manner, the only reason that can makes both CPU Master is sync system between 2 CPU ( FH Module and Fiber Optic Cable ) , Please check :

1. system is configured as H system

2. all connection between CPUs are OK.

Regards,