Abstract: A tracing apparatus communicably connected to a programmable logic controller (PLC) that inputs and outputs a signal based on a ladder program, includes a constituent element setting unit configured to set a plurality of constituent elements to be traced among the constituent elements of the ladder program, a tracing data acquisition unit configured to acquire tracing data indicating a signal state of the constituent element at a specified timing, at a predetermined sampling cycle, a section detection unit configured to detect a sampling cycle section in which two or more of the acquired tracing data corresponding to the constituent elements simultaneously change, a change sequence calculation unit configured to calculate change sequence of signals of the constituent elements simultaneously changing in the detected sampling cycle section, and a change sequence output unit configured to output the calculated change sequence of the signals of the constituent elements.

Abstract: A tracing apparatus communicably connected to a programmable logic controller (PLC) that inputs and outputs a signal based on a ladder program, includes a constituent element setting unit configured to set a plurality of constituent elements to be traced among the constituent elements of the ladder program, a tracing data acquisition unit configured to acquire tracing data indicating a signal state of the constituent element at a specified timing, at a predetermined sampling cycle, a section detection unit configured to detect a sampling cycle section in which two or more of the acquired tracing data corresponding to the constituent elements simultaneously change, a change sequence calculation unit configured to calculate change sequence of signals of the constituent elements simultaneously changing in the detected sampling cycle section, and a change sequence output unit configured to output the calculated change sequence of the signals of the constituent elements.