A high speed programmable controller based on Petri net

The authors propose a novel programmable controller based on the use of a Petri net to describe the status of a whole system. The proposed programmable controller consists of a fire unit and an input handling unit. It does not use any processors, because places express the status of the controller, not processes. The fire unit is a very-wide-word ASIC (application-specific integrated circuit) memory that checks whether a transition is fireable or not in two memory cycles. Since the input handling unit can choose the earliest arrival signal input using the mutual exclusion rule, it is not necessary to scan all inputs. It takes only four memory cycles for the proposed system to process one input signal. Therefore, it is possible to realize much faster control than with the conventional system, and the new system has a mathematically analyzable foundation