6.1 INTRODUCTION

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Ideal for parallel control problems

Basic logic functions are shown below,

We can model various logic functions with Petri nets,

Reachability allows us to determine if a state (set of places) is possible given an initial condition.

Boundedness determines whether the number of states will be controlled, or grow/shrink.

Deadlock and liveliness - will the controller find itself unable to continue.

The procedure for producing ladder logic and other programs from the Petri Nets, is identical to producing Ladder Logic for SFC diagrams.

Petri nets have been used for the modeling, control and validation of the control model [Teng and Black, 1988]