DESCRIPTION METHOD FOR CONTROL PROGRAM

PROBLEM TO BE SOLVED: To efficiently prepare the control program of a programmable controller corresponding to the specification of controlled system equipment by selecting ladder parts and defining an operating command to contacts constituting user interface parts to the controlled system equipment or output signals from contacts constituting external interface parts to the controlled system equipment. SOLUTION: When a user select the kind of a motor (controlled system), the internal circuit of a ladder circuit showing the control procedure of the motor is selected from a parts storage part 13. Besides, the user interface parts (motor parts, for example), or external interface parts corresponding to the internal circuit are presented as well. In this case, the operating command to the contacts constituting the user interface parts to the controlled system equipment as the contacts of these ladder circuit parts is defined and the output signals from the contacts constituting the external interface parts to the controlled system equipment as the contacts of the ladder circuit parts to the controlled system equipment are definded.