PURPOSE: To simplify the circuit constitution and to decrease the number of elements of a controller, by making use of the resolution of an A/D converter to feed a number of ON/OFF signals directly to a digital data processor.

CONSTITUTION: The resolution of an A/D converter is utilized to feed a number of ON/OFF signals directly to a digital data processor without performing timing control or selection control. For instance, the reference voltage Vs is supplied to a D/A converting circuit network D/A consisting of input switches S1WS5, resistances RW32R, an addition amplifier Σ, etc. At the same time, the digital signals corresponding to the ON/OFF signal sent from an operation switch, a detection switch, etc. are supplied via the switches S1WS5 and converted into analog signals. This analog signal is converted into a digital signal by the network A/D and fed to a control part 20 of the digital data processor.