PROGRAMMABLE SEQUENCE CONTROLLER

PROBLEM TO BE SOLVED: To provide a sequence controller in which the extendibility of the number of inputs/outputs is excellent. SOLUTION: An extended unit is provided between a conventional sequence controller 10 and an object 17 to be controlled. A specific extended unit is selected from a digital output extended unit 22 (220-7) and a digital input extended unit 23 (230-3) according to a selection signal outputted from an output unit 12, and the output of each extended unit is connected with a digital output unit 12 or a digital input unit 13 in parallel. Then, data outputted to the selected digital output extended unit 22 are transmitted to the object to be controlled, and the digital information of the object to be controlled is read from the selected digital input extended unit 23. A channel is selected from an analog input extended unit 24 (240-3) according to a selection signal outputted from the output unit 12, and read through an analog input unit 14 to a control unit 11.