Redundant optical Modulebus from AC800M CPU?
I´m building a new controller system for temperature measurement in total of two turbines, each with an identical configuration in the process. For reliabilty reasons I´m considering a redundant PM858 configuration running both turbine applications "in one". The I/O-clusters consist of some local I/O:s in the CPU(s) cabinet and two branches with I/O:s, one each per turbine. All I/O:s should be connected via the (optical) Modulebus.
Setting up a redundant Modulebus for each I/O-branch I see no problem, I just use TU840 + TB840 but how do I make them redundant (single fault tolerant) at the CPU? If I connect one of the both line to each CPU they won´t back up for each other right? Single fault tolerance is uf essence here. In another installation I used Profibus and a redundant CI-module on the CEX-bus to accomplish exactly this but I can´t find any for Modulebus that makes the same sense to me....
Please see attached sketch. Please note that the number of I/O-clusters, modules etc are just examples.
Hope you can help.
If any one controller fail, still the IO cards are visible to the other controller. or
If any TB840 or module bus failure will force the CPU switchover. I believe this setup gives single fault tolerant solution with redundant CPU and TB840.