Safety controller and safety control method

A safety controller comprising:

• a first carrier signal generation unit that generates a first carrier signal defining a control cycle of a control target;
• a second carrier signal generation unit that generates a second carrier signal defining a control cycle of the control target, the first carrier signal and the second carrier signal having the same cycle and a predetermined phase difference;
• a first interrupt signal output unit that outputs a first interrupt signal in a cycle synchronous with the cycle of the first carrier signal generated by the first carrier signal generation unit;
• a second interrupt signal output unit that outputs a second interrupt signal in a cycle synchronous with the cycle of the second carrier signal generated by the second carrier signal generation unit;
• and
• a control unit that executes a plurality of tasks for executing processing related to control of the control target and controls the control target by switching and scheduling a plurality of time partitions according to an output of the first interrupt signal from the first interrupt signal output unit and an output of the second interrupt signal from the second interrupt signal output unit, at least one of the plurality of tasks being allocated to each of the plurality of time partitions,
• wherein the control unit stops the control of the control target upon detecting, as an abnormality related to the first interrupt signal and the second interrupt signal, a fact that the first interrupt signal and the second interrupt signal are not output in a predetermined order.