Abstract: An input signal (A) and an output signal (B) with respect to an output memory (8), and an output signal (C) of an output circuit (9) in a programmable controller are compared with each other. The identification of and an abnormal part is displayed in accordance with the comparison results.

Abstract: A numerical control system includes an information input-output circuit (3), a processing unit (1), a display (4) and a memory (2). The information input-output circuit (3) has an input (31) for the address numbers of the information elements to be displayed, an input (32) for the time scale with which the display is presented, an input (33) for the address number of a trigger information element, an input (34) for a command for selection of a repetitive picture or a set of non-repetitive pictures, and an input (35) for a delay time, if any. The processing unit (1) has a input (11) for selecting address numbers of the information elements to be displayed, an input (12) for selecting the time scale with which the display is presented, an input (13) for selecting the address number of a trigger information element, an input (14) for conducting a command for selecting a repetitive picture or a set of non-repetitive pictures, and an input (15) for selecting a delay time.