Input-output control unit, PLC and data control method

A data control apparatus includes an analog signal input interface for receiving an analog signal from a first device, a communication interface for receiving correlation information indicating addresses of storage areas in a storage and conditional values associated with the storage areas, and a data controller for writing a digital value generated from the analog signal into one of the storage areas. The data controller includes a cam switch block for acquiring a reference signal generated from an input signal input from a second device and comparing a value of the reference signal with at least one of the conditional values, and a logger block for switching the storage area into which the digital value is written, on the basis of the comparison in the cam switch block, and writing the digital value into the storage area.