FAILURE DIAGNOSIS CIRCUIT AND FAILURE DIAGNOSIS METHOD OF CONTROL DEVICE

PROBLEM TO BE SOLVED: To realize prevention of an erroneous output of a control circuit due to a failure of a diagnosis circuit without increasing an amount of hardware, in a control device in a system having high reliability, including the diagnosis circuit.SOLUTION: In the control device in the system having high reliability, a diagnosis instruction signal from an upper-level device is received at multiplexed communication control circuits, and a diagnosis instruction signal to the diagnosis circuit and a diagnosis permission signal are generated. By monitoring a diagnosis output of the diagnosis circuit by multiplexed diagnosis permission circuits using the diagnosis permission signal, the prevention of an erroneous output due to a failure of the diagnosis circuit is realized, and a problem of hardware increase by multiplexing of the diagnosis circuit is solved.