Validation of Discrete Event Processes implemented on PLCs based on Petri Nets
Abstract: Discrete Event Systems (DES) are commonly found as supervisors in industrial applications, implemented by Programmable Logic Controllers (PLC). Modeling DESs with IOPT Petri Nets (IOPT PNs), a class of PNs extended with input-output, allows translating the models directly to PLC programs when the PNs are bounded.Validation is required to assess the PN-based PLC programming tools are error-free. Coverability trees based on the node dominance concept are proposed to consider just DESs with finite reachable sets. Operation cycles, and the associated sequences of transitions, are used to validate the produced code by assessing whether the PLC code reaches all possible states.Promising results were obtained in practical validation cases of the PLC code production, by the exhaustive test of reachable states determined from the PN representing the industrial process (DES). Moreover, the proposed methodology showed that it is possible to anticipate the detection of design problems and study the effects of restrictions imposed by hardware.
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