A controller system includes a controller, and a plurality of input/output control devices connected in series with the controller so as to allow communication therebetween. Each of the plurality of input/output control devices is configured to be connected with a sensor device. Each of the plurality of input/output control devices calculates a one-shot timer activation counter based on a total number of the sensor devices being objects to activate a one-shot timer out of the sensor devices that are connected with another input/output control device between a subject input/output control device and the controller.