Transmission redundancy in safety systems for railway transport using the example of the axle counter

Availability of the modern safety systems for railway transport depends on telecommunication infrastructure for communication of distributed subsystems. In order to limit risks related to transmission interference, various redundancy technologies of transmission networks (media, devices) are used in industrial systems – sometimes including their automatic reconfiguration. This article presents an analysis of the considered methods to provide high transmission availability in the axle counter system, as well as the implemented tailored solution – protocol UniPRP which uses parallel transmission of the doubled data. This solution is an adaptation of those presented in the series of technical standards: IEC 62439 Industrial communication networks - High availability automation networks.