A taxonomy for modelling safety related architectures in compliance with functional safety requirements

Abstract

This paper presents an extension and refinement to the modelling of architectures for safety functions as suggested in IEC61508-6. We propose an implementation oriented taxonomy providing an easy and unambiguous approach to model real life architectures in conformance with IEC61508. Modelling safety related architectures with this taxonomy results in the following benefits: (1) A clear and unambiguous approach to the selection of required diagnostic techniques and measures (IEC61508-2 and IEC61508-3) based on the Safety Integrity Level (SIL); (2) Quick estimates of Probability of Failure on Demand (PFD)/ Probability of Failure per Hour (PFH) / Safe Failure Fraction (SFF) values in relation to the quantitative SIL requirements; (3) Optimising the design and performance by allocating specific diagnostic techniques to specific elements of the architecture; (4) Improved overview and understanding of the architecture supporting the development and certification process. The taxonomy is part of ongoing effort to automate the selection and conformance checking of diagnostic techniques and measures with IEC61508. © Springer-Verlag Berlin Heidelberg 2007.