A b t ractThis paper proposes a new programmable controller baaed on the usage of Petri Net to describe the status of a whole syrtem. The proposed programmable controller consists of Fire Unit and Input Handling Unit. And it does not UM MY processon, because pluea u p r e~ the status of the controller, not proasses. Fin Unit L an ASIC memory with very wide word to check whether a transition is fireable or not in two memory cycles. Since Input Handling Unit can choose the earliest arrival signal input using mutual exclusion rule, it is not necessary to scan d input. It takes only Cour memory cyclu, Cor the newly proposed system to process one input signal. So it is possible to realize much Cuter control that the conventional system and it has mathematically analyzable foundation.

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In this paper, we propose an automatically generating method of Petri net. On generating, we divide the whole system into some sub-modules, take note of the hardware construction of the system, and prepare the Petri net modules in advance, each module corresponding to each constituent element of the system. The Petri net modules have a hierarchical structure. We define a textual form grammar to represent the Petri net modules, and the linkage rule to connect each sub-module. The controlled objects can be also constructed as a module of the system, so the simulation and analysis of the system can be executed easily.

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