Data control device, programmable logic controller and data control method

A data control device (20) comprises: An analog signal input interface (243) which receives analog signals from a first machine (63); A communication interface (260) which can receive related information indicating the followings: Each address of a plurality of memory fields (251, 252) included in the memory portion (250), and condition values associated with storage areas (251, 252); A data control unit (210) which writes a digital value generated from an analog signal to one of the plurality of storage areas (251, 252). The data control unit (210) comprises: A cam switch block which takes a reference signal generated by an input signal input from a second machine (60), and compares the value of the reference signal with the condition value; and a recorder block which, according to the comparison of the cam switch block, switches the storage areas (251, 252) written the digit values and writes the digital value.