Application of IEC61508 SIL Recommendations to a Control-model Based Lifecycle

This paper addresses the question of how to apply the Safety Integrity Level (SIL) requirements of the generic industrial functional safety standard IEC61508 to software developed using a control-model with target source code automatically generated from the model itself. This standard is being widely adopted in Europe, but betrays its age as the established techniques it references do not explicitly include model based software development now becoming standard in the automotive industry. It has also been criticised for being very prescriptive. The approach taken here is to determine the goals required by the standard and then recommend techniques to achieve these for each of the control-model based software development lifecycle phases. This study considers SIL 1, 2 and 3 requirements.