Extending the expressive power of fault trees

Fault trees (FT) are an established model for reliability and safety analysis of technical systems. They are combinatorial models and thus cannot consider state dependencies or temporal order of events. We recently proposed state-event-fault-trees (SEFTs), an extension of fault trees with state/event semantics, as a reliability model for embedded systems. In this paper, we demonstrate its application and introduce a number of new gates that are especially suitable for software-controlled systems. SEFTs are a compositional model where the components are connected by two types of ports, state ports and event ports. Together with the extended set of gates, SEFTs allow both more accurate modeling of embedded systems and integration with design phase models such as Statecharts to achieve an integrated development process. We show the practical application of SEFTs to a small case study and introduce our tool project ESSaRel.