PURPOSE: To discriminate the appropriateness of mounting easily and to improve safeness by previously setting up inherent positional information indicating a position on which a control module is to be mounted and comparing the set up information with actual mounting position information.

CONSTITUTION: The control module 1 is formed by a comparator 4 and a control arithmetic circuit 6 and a position on which the control module 1 is to be mounted and a control module to be set up are specified by a set pattern obtained by turning on/off a switch S1 and S2 respectively. When the specified module 1 is inserted into the mounting position, the corresponding module 1 is electrically connected with the switch S2, when both the module 1 and the switch S2 coincide with each other, the mounting is regarded as correct one. The information specified by the switches S1, S2 are compared by a comparator 4, and in case of incorrect mounting, an alarm circuit 5 is driven to generate an alarm, and the control arithmetic circuit 6 is actuated and its output signal OUT2 is turned off.