A Basic Study of Fieldbuses Used for Railway Signalling Control

A fieldbus used for railway signalling control must (1)support high reliability and(2)support redundancy and fault tolerance required by railway signalling devices. Based on the above two principles, the paper elaborates on several facets related to selecting fieldbuses used for railway signalling control.The paper also defines the concept of quasi fail safety, describes the protocol structure which must be adopted and the requirements and constraints which must be satisfied by a fieldbus for supporting the fail safety of railway signalling control.