This thesis introduces the Petri net and the Petri net model of a data link layer protocol, and illustrates the properties of the net with S-invariant and T-invariant.

Further simulation illustrates the effect of the adjustment. Theory of colored Petri net is introduced to condense the Petri net model of multi-axis servo control progress.

This article discusses the hybrid system model of each layer and gives a detail description for the process layer. Petri net approaches are presented to model chemical control hybrid system.