PM891 Redundant Controller going to Fault mode
I also tried to power off the primary controller and download only to the secondary. The controller goes to online mode after the download but all the DO modules and some AO modules goes to fault.I also lost module bus communication with the last row of the module rack.
Right now it is working with just the Primary controller.
In another panel we had the problem of the controller continually switching between Primary and Secondary. One would go to fault and the second would become primary.Then immediately the secondary would go to fault and Primary would take over.In short it was continually oscillating. This resulted in full disturbance of the module bus and row by row modules would randomly go to channel error and then normalise after a few seconds disturbing the whole plant. Controller reset ,initialization, changing modbus cables made no difference. We started isolating some field signals and the oscillations stopped and we put the controllers back into operation. Again now after few weeks the secondary controller is again going to fault mode.
Kindly could you suggest what could be the reason.
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Please consider filing a support case with your regional ABB support center to obtain professional assistance.
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