Principles of safety bus system

Summary form only for tutorial. This paper is partly a tutorial paper, it describes the requirements and specifications to be considered and fulfilled to design safety bus systems. Modern distributed control systems are connected via bus systems, and need effective and uninternpted communicotion between all bus stations. Thertfore, it is necessary that these communications are fault tolerant and safe. Especially for safety related systems, additional safety layers are required to fulfil these requirements. In a safety related application it is important to understand that the sqfe protocol alone connot fulfil this requirement without two safe hardware ends (source node and destination node). Only the conjunction between safety related protocol and safety related hardware nodes can fulfil the requirements for safety related bus systems.