To easily constitute a system used by means of switching plural feedback signals and a system which simultaneously inputs the plural feedback signals to an adding point in a control system where feedback loops are independently constituted for respective sensors.

The detection signals of corresponding single sensors 140, 150... are inputted to respective control boards 10, 20... and feedback signals outputted from signal processing parts 17, 27... are outputted to corresponding sensor buses 2-1 to 2-n with addition points 12, 22.... Feedback signal selection parts 18, 28... select the outputs of the self-signal processing parts 17, 27... and the arbitrary feedback signal among the feedback signals from the sensors buses 2-1 to 2-n and they are supplied to the addition points 12, 22... in the respective control boards 10, 20....