PROGRAMMING SYSTEM FOR SEQUENCE CONTROL AND CONTROL UNIT FOR EXECUTING PROGRAM FOR SEQUENCE CONTROL

A programming system for sequence control including a display, a functional symbol definition memory for storing functional symbols, each for defining one of steps in a sequence showing control procedure for a control object, respectively, a sequential diagram generating and display unit including a sequence table, and an input device for inputting in order the functional symbols along with process contents to be executed in the functional symbols, respectively, into the sequential diagram generating and display unit, which displays the functional symbols along with the process contents as a sequential diagram on a program generating screen of the display and stores the process for each of the steps in the sequence table. The programming system for sequence control further includes an execution program generating unit for generating an execution program that is executable by the control unit for the sequential diagram based on the memory contents of the functional symbol definition memory and the sequence table, an execution program transfer unit for transferring the execution program to the control unit, a sequential diagram reverse generating unit for reversely generating the sequential diagram from the execution program and a reversely generated sequential diagram display unit for displaying the sequential diagram on the program generating screen.