ABSTRACT
Industry 4.0 opens up for a new area of industrial automation and challenges established methods for the assurance of safety. Traditionally, the architecture is a major criterion for the determination of safety levels and so-called designated architectures serve as a basis for the calculation of the PFH (EN ISO 13849-1, 2015, IEC 62061, 2015). This easy approach is, however, limited to systems which can be directly mapped to the assumptions. For modern, software-intensive systems the extended possibilities for online diagnostics makes this mapping particularly difficult. To make the PFH calculation more flexible and transparent, we have derived Markov-based analytic equations for the designated architectures. In this paper, we will sketch our approach for a single-channel system with diagnostics. We compare the result to Petri net simulations, analyze the influence of individual parameters and argue how these models can be extended to more complex systems even beyond the realm of the designated architectures.
