Hi Lukas - How you can resolved problem HW Connection Error 9166
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I had the problem that the controller load was to high and the profibus load was also to high. After reducing the controller load, (slower task-cycle times), and slplitting the profibus to several profibus master (several CI854) there was no error any more. I think the load of the CI854 was to high.
But this was not an AC800M controller it was an AC800PEC controller.