Jochen Spranger Funlite a Parallel Petri Net Simulator 1 Introduction

In the development of provably error free control software for manufacturing systems the application of Petri nets is a well known approach One of the main advantages of Petri nets are their sound mathematical background which make it possible to analyse and validate the qualitative and quantitative behavior of a Petri net system by formal methods The gap between the validated Petri net model and the needed control software can be closed by directly synthesizing the control software form a Petri net speci cation One way to achieve this is to assign control code to the transitions and use a Petri net simulator to simulate the token ow of a Petri net We use save hierarchical Place Transition nets to develop modularized control software for manufacturing systems Each machine controller is modelled in a separate subnet Those subnets are connected by places which re ect the communication between the con trollers For this kind of Petri nets we have realized a parallel Petri net simulator FUNlite especially designed for fast execution speed low memory consumption and low communica tion overhead In FUNlite we generate for each subnet a fast sequential Petri net simulator Each subnet simulator is mapped on a di erent processor When simulating a Petri net system the speed of the transition enabling test plays an important role In FUNlite the enabling test is highly simpli ed by a method characterizing the enabling of a transition at a given marking by a simple number comparison Communication places where a con ict between subnets exists are administrated by the lockset method which is speeded up by an analogous number comparison technique The FUNlite system has been implemented on a Transputer system consisting of T Transputers which are connected by C communication switches The code is written in INMOS C which is an extension of ANSI C by the CSP model for parallel pro gramming The main parallel features are processes synchronous communication through channels and semaphores This paper is organized as follows Section gives a short introduction in Petri nets Section presents the simulation engine for the subnets Section and show the internal and external administration of communication places Finally some conclusions are given