Reconciling flexibility and robustness in industrial automation systems, and living happily ever after

Many automation systems are used in safety-critical environments, in which any nondeterministic timing behavior of the software may damage equipment or even threaten the health of people. Making software behave deterministically usually relies on hardware-bound optimizations, leaving little room for abstraction layers. This, however, has a negative impact on several important software qualities such as portability, maintainability, or scalability. As a consequence, it becomes difficult to use the same software across different platforms, scale it up or down to changing requirements, or reuse code across different families of products. In this article, we show how both flexibility and robustness can be achieved for real-time automation software. To this end, we present the mechanisms behind the component-based execution framework FASA. This framework offers a platform abstraction mechanism, which allows developers to port it to various platforms in a well-defined manner while maintaining its deterministic qualities. Furthermore, FASA supports runtime reconfigurations and software updates while executing real-time applications without any disruptions. For each of these concepts, we detail our reference implementation.