CONTROL METHOD OF DUPLEXING INPUT SIGNAL CONTROL DEVICE AND DUPLEXING OUTPUT SIGNAL CONTROL DEVICE, DUPLEXING INPUT SIGNAL CONTROL DEVICE THEREOF AND DUPLEXING OUTPUT SIGNAL CONTROL DEVICE THEREOF

PROBLEM TO BE SOLVED: To provide a control method of a duplexing input signal control device and a duplexing output signal control device capable of reducing the size of the device by commonly using a program and capable of performing self-diagnosis any time.SOLUTION: The duplexing input signal control device and the duplexing output signal control device include: a first input/output signal control section 10 and a second input/output signal control section 20 which have the same configuration for setting a self-control mode on the basis of a control mode of two systems; an input section 50; an inter-CPU communication circuit 40; and a transmission circuit 30. One of the first input/output signal control sections includes: a switch 14; a first CPU 12; a control mode storage 13; and a program storage 11. The control method of the duplexing input signal control device and the duplexing output signal control device includes the steps of: comparing the control modes to each other; and responding an input signal when the control modes coincide with each other, responding an inconsistent signal when the control modes are inconsistent with each other, and stopping the execution upon receiving a stop instruction. By sequentially performing comparison the control mode, the reliability of the input signal is increased.