Probabilistic delay time analysis in networked automation systems

The introduction of non-deterministic networks to the automation field leads to new questions in the analysis of the resulting systems often called networked control systems (NCS). To determine reaction times not only the cycle times of the controllers but also the network delays have to be taken into account. The problem further increases in reliability analysis. Here the failures of a variety of components have to be considered. For this purpose probabilistic model checking (PMC) is a promising formal approach. This paper investigates the application of existing techniques and tools from PMC to the analysis of delay times in NCS under the consideration of component failures. A key idea in the presented approach is that the nature of signals in automation systems is taken into account. A case study shows how properties, relevant for the reliable functioning of an automation system, can be checked