PURPOSE: To confirm the coincidence of contents of microprogram P of plural controllers sharing a device to be controlled in a short time and to prevent the fault caused by the disturbance of the control information, by performing comparison of the edition number information among those microprograms μP.

CONSTITUTION: The edition number information of the μP are read out of a microprogram memory part 14 and the systems A and B of an information memory part 15 are written into addresses 0 and 1 respectively when the power supply is applied to a microprocessor 13 of the system A for initialization. Then the output of an FF 16 of the system B is checked and decided as 0. Thus an FF 16 of the system A is set at 1 and the operation is started. When the power supply is applied to the system B for initialization, the same operation as that of the system A is carried out. A processor 13 of the system B compares the edition number information on the P of the system A stored in an address 0 of the part 15 of the system A with the maximum address of the part 14 of the system B or the edition number information on the address 1 of the part 15. Then the coincidence is obtained from this comparison, the contents of the part 15 of the system A are copied to the part 15 of the system B. Then the operation is started after setting the FF 16 at 1. When no coincidence is obtained, the processor 13 of the system B erites the fault information to the specific areas of both parts 15 to stop the operation.