Deriving real-time requirements for software from safety analysis

Abstract

One of the main problems in industrial applications of computer systems is software safety, i.e. question if software can contribute (often indirectly, through a long chain of intermediary events) to an accident. Adequate identification and definition of safety requirements is crucial for safety-critical software systems. The paper presents a systematic way of derivation of software safety requirements based on a formalised model of fault trees. The approach is demonstrated through a case study. The presented approach is particularly focused on timing requirements for software which result from the safety analysis performed for the whole application.