A program comparison apparatus includes: a set alignment unit that divides a comparison source-program which is a first FBD program into sets of program components connected to one another, and rearranges the sets in a line along a Y-axis direction which is a vertical direction in ascending order of execution, and also divides a comparison edited-program which is a second FBD program into sets of program components connected to one another, and rearranges the sets in a line along the Y-axis direction in ascending order of execution; a difference detection unit that detects a difference in the sets between the comparison source-program and the comparison edited-program rearranged as difference information; and a difference display control unit that causes the sets of the comparison source-program and the comparison edited-program that are rearranged to be displayed within a screen of a display device.

A program comparison apparatus includes: a set alignment unit that divides a comparison source-program which is a first FBD program into sets of program components connected to one another, and rearranges the sets in a line along a Y-axis direction which is a vertical direction in ascending order of execution, and also divides a comparison edited-program which is a second FBD program into sets of program components connected to one another, and rearranges the sets in a line along the Y-axis direction in ascending order of execution; a difference detection unit that detects a difference in the sets between the comparison source-program and the comparison edited-program rearranged as difference information; and a difference display control unit that causes the sets of the comparison source-program and the comparison edited-program that are rearranged to be displayed within a screen of a display device.

To make it easy for a user to extract individual data from time series data. A programming support apparatus or a programmable logic controller (PLC) analyzes a user program to decide an extraction period of individual data. For example, in the user program, an instruction word for setting the extraction period is described. A collection part repeatedly collects device data stored in at least one device to form time series data having periodicity. An extraction part extracts individual data in each extraction period from the time series data. An addition part adds identification information for identifying each piece of the individual data extracted by the extraction part to each piece of the individual data.

A control system includes a programmable logic controller to execute at least one program and a programming support device to create the program. In the control system, an end process time measurer measures an execution time of an end process performed after execution of the program in a single scanning process, and a display displays the execution time of the end process on a screen in the programming support device.