In: Zhou, M.C.: Petri Nets in Flexible and Agile Automation, pages 93-108. Dordrecht, NL: Kluwer Academic Publishers, 1995.
Abstract: This chapter describes a new method for automatic generation of a ladder list program for a programmable logic controller used for sequence control of industrial machinery. To enhance the readability of specification of the sequence control, which is expressed by a sequence of motions and logic, the sequence of motions combined with the on/off readings of sensors is specified by Petri nets and the on/off logic of switches and actuators is specified by logic tables. The control specifications which are independently expressed by Petri Nets and the logic table are converted to the ladder list program by rules. The generated program can be linked to the simulator of the machine motions to simplify verification and debugging of the described control specifications. The proposed method has proved to be effective through the application to sequence control of an press machine and it has reduced the period for making a ladder list program by about 75% as compared with the conventional method which directly prepares a ladder list program.