Analyzing the Behavior of IEC 61499-based Control Software

Control software collects signals from sensors, processes them, and uses the results to drive actuators. This tight interaction means that developers or tools cannot directly infer the overall behavior of control software without also knowing the physical system. This particularly affects developers of IEC 61499-based software due to the introduced event-driven execution model. It allows them to precisely define the execution order of components, but can hinder understanding of the control flow, which may depend on data values. For maintaining or testing control software, developers can therefore benefit from visualizations of the control software behavior. This paper categorizes the structural and behavioral models of IEC 61499, illustrates their usage based on a demonstration example, and outlines how the application structure affects the presentation of the behavior. We also propose possible extensions. Distributed design patterns facilitate reuse and adaptability, but the implicit interactions between components may hinder understanding of the control software. Future work should therefore focus on compensating the disadvantage, for instance, by visualizing these interactions.