Event Storms in IEC 61499 Applications

The event-based IEC 61499 standard was established to complement the cycle-based IEC 61131 standard for PLC applications. It focuses on the design of an application employing a function block based approach, whereas the implementation targeting either standalone or networked embedded systems is kept transparent. The individual blocks within such a system interact with each other via event and data signals. Their execution influences the logical and temporal correctness of the respective applications. This paper investigates event storms - situations where multiple events are emitted almost simultaneously - with regard to the systems correctness by using an experimental setup. Furthermore, a monitoring approach is proposed that when combined with other means provides a potential solution to mitigate problematic or erroneous behavior caused by such event storms.