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Kamran AhmadiSpecialistanswered

redundant communication between two Masters S7-400 and Yokogawa?

DCS EngineeringYokogawa CENTUM VP

Hello! I have recently run into a problem regarding my recent project. I need to create a redundant communication interface between two masters, a siemens S7-400(as master) and a unknown yokogawa(also as master). We need to transfer parameters between these controllers, in both directions that is. They have stipulated that it needs to be a redundant. So i will need to have a DP/DP coupler to allow two masters to communicate and a secondary one to create the redundancy. My idea was to use OR gates on both sides to make up for the redundency. Is there anything else I should think about? Should I use the diagnostic bit to determine if one the the DP/DP couplers have failed or isnt recieving and information from it(like profibus fail och other fault like line break)? Thanks in advance

Asked Jul 21, 2026, 9:34 PM

2 answers

Substation automation specialistSpecialist

I would suggest go for the ethernet connection between S7 CPU and Yokogawa CPU and get the Watchdog bit from the Yokogawa CPU that which one is master out of two Because i had expirienced the same In case of yokogawa system only master CPU will be sending the data and Standby CPU will not send any data Hope this will Help you

Answered Jul 21, 2026, 9:37 PM

Helpful · 0
Substation automation specialistSpecialist

In your proposition you still have a single point of failure (from the communication point of view of course, because you do not have two CPUs) being the DP interface of the CPU. If you have a problem on that interface (or on that bussegment) both communication channels will fail. You could add an IM467 as second DP Master in the S7-400, connecting the second DP/DP coupler to it, having two separate busssgements to the yokogawa. To check the communication, I would suggest to exchange a lifebit with the remote system on both communication channels. This covers the complete communication path (cables, ..) but also that remoteapplication is still alive.

Answered Jul 21, 2026, 9:38 PM

Helpful · 0

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