Control device and control method for blocking a control signal to a target device

A control method for a controlled target device that includes a plurality of communication units connected to a plurality of measurement control devices through a plurality of networks, a control unit, a storage unit, a first monitoring unit and a second monitoring unit that are independent of each other, and a blocking unit, the control method comprising:

• receiving, by each of the plurality of communication units, data from a respective measurement control device;
• calculating, by the control unit, an operation signal for controlling the controlled target device on the basis of data received from the communication units;
• storing, by the storage unit, the data from the communication units, the storage unit includes a first data storage area that stores therein first data from the communication units, and a second data storage area that stores therein second data from the communication units;
• checking, by the first monitoring unit and the second monitoring unit, the first data and the second data obtained from the storage unit against each other to determine whether the first data and the second data indicate identical information;
• outputting, by the first monitoring unit and the second monitoring unit, a blocking signal when the first data and the second data are not determined to indicate identical information;
• blocking, by the blocking unit, the operation signal from being outputted by the control unit to the controlled target device upon receiving the blocking signal output from at least either one of the first monitoring unit and the second monitoring unit;
• receiving, by the controlled target device, the operation signal when the operation signal output from the control unit is not blocked;
• and
• executing, by the controlled target device, the operation signal, wherein the operation signal controls the controlled target device.