Vital serial link

A vital serial link for linking, in a railway signaling system having two opposite directions of transmission, a plurality of data processors which act on information communicated in the form of link information signals, into a vital serial communications network, said vital serial link comprising:

• at least two vital serial controllers, connected to respective processors, each controller operating in both directions of transmission, said controllers being connected in back-to-back relationship in the vital serial link, each of said controllers including:
• means for storing a plurality of link parameter signals, each of said link parameter signals including a unique numerical relationship indicating that a specified first processor originated a signal and that a designated second processor is to receive said signal, the unique numerical relationship being provided for each possible combination of signal-originating processor and signal-receiving processor;
• wherein
• upon receipt of a signal, said signal receiving processor can discriminate signals sent to said receiving processor, and determine which processor in said network was the signal originating processor;
• said vital serial link further comprising communicating means for communicating signals, including said link parameter signals, between said plurality of data processors in said network.