Implementation of a large Petri net by a group of Petri net controller

The authors propose a Petri net control system to implement a large Petri net. When a large Petri net is to be implemented, it is divided into several smaller sub nets and each sub net is implemented by a Petri net controller made of LSI. So this system consists of a group of Petri net controllers and a communication controller. In order that a group of sub nets working as an original large net, it is important to keep the consistency of tokens among these sub-nets. Here, the authors present a revised Petri net controller to make a divide-and-rule system. A register, called the FCTR (fire check transition register), is added to hold fireable transition. This makes it easy for each controller to check the consistency of tokens in places shared among sub-net controllers. A new communication protocol among controllers and its hardware implementation are also proposed. The revised Petri net controller will be implemented with little increase in hardware.