Automatic Generation of Relay Logic for Interlocking System Based on Statecharts

Computer-based Interlocking System (CIS) is a kind of widely applied safety-critical system in current signaling industry. CIS always uses relay logic to describe interlocking safety logic. Normally, all logic is designed by experienced signaling engineer manually, this develop mode is low-efficient and expensive. This paper presents a new logic design model. In this new model, a component-based model is used to describe topology of station layout, the topology data is analyzed and state charts are used to describe safety logic of interlocking. Finally the state charts are transformed to relay logic. The entire logic generating procedure can be fulfilled by software tools automatically, so efficiency is improved greatly. The introduction of state charts also makes formal verification of safety logic possible, which can guarantee that the generated logic is safe.