A control system includes a support device used for developing a user program to be executed on a controller, and a display device that provides a supervisory control screen by referring to information held by the controller. The support device extracts a relationship between an output signal and one or more input signals defined by the user program and generates input-output correspondence information, and transmits the input-output correspondence information or screen data reflecting the input-output correspondence information to the display device. The display device provides, on the basis of the input-output correspondence information or the screen data reflecting the input-output correspondence information, the supervisory control screen showing the current value of a selected output signal and the current value of one or more input signals associated with the output signal by referring to the values of input and output signals held by the controller.