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Hybrid Synchronous–Asynchronous Execution of Reconfigurable PLC Programs in Edge Computing

In edge computing, heterogeneous automation tasks, such as networked motion control and reconfiguration management, have diverse weights on determinism and flexibility. Such heterogeneities escalate the demands on the runtime environments (RTEs) of programmable logic controllers to provide the best-suited rather than one-size-fits-all execution policies for reconfigurable programs. This article presents the proposal and implementation of a novel IEC 61499-based RTE capable of offering hybrid synchronous and asynchronous execution models for function block (FB) based programs. We also construct a runtime reconfigurable FB-type repository by realizing a just-in-time FB-type definitions compiler in the RTE. Finally, we evaluate and compare the proposed RTE and state-of-the-art works by running a set of synthetic benchmark programs and a realistic networked motion control kernel and application. Experiment results from the benchmark programs have shown a maximal 40% faster execution speed in our RTE. Furthermore, our RTE can ensure fewer jitters during distributed motion control with a 1-ms cycle time on a realistic motion control testbed.