Automatic programming for sequence control

Abstract

Industrial plants are controlled using sequence control programs run-ning on programmable controllers. Sequence control program design has been carried out manually, and an increase in applications of pro-grammable controllers has caused a shortage of programmers. There-fore, automatic programming systems are strongly required in this field. Controllers receive operation signals from plant operators and cur-rent plant states through sensors, then select actions that have to be ex-ecuted. Sequence control programs consist of a large amount of con-trol logic (about 100K program steps) for such decisions. The following problems were found in previous manual designs of se-quence control programs: First, control logic is often omitted. Second, programs might include some mutual contradictions. Third, information that is necessary to complete one program step is