The Research On Safety Protocol Of PROFIBUS

The basic demand of railway is to ensure the safety of information. To carry out the safety of information, some special information safety technique is provided besides some routine technique safety standard. Failure-safe is the most important in all of the information safety techniques. Fieldbus technique can't be used in railway system if there is no information safety technique. It's the kernel technique of Fieldbus.In all of the Fieldbus, PROFIBUS allows the data to transmit several times to ensure reliability, and it has safety precaution. PROFIBUS is a special fieldbus which is authorized only by the safety. So PROFIBUS is broadly used in railway systems, especially in Europe Train Control System.ETCS level STM is a Specific Transmission Module in ETCS. It mostly provides current engine signal when the train collocated with ETCS equipment is run in the exact line. It translates received national system into standard ETCS message, then send it to ETCS.In this paper, ETCS level STM protocol is analysed. It mainly introduces the safety realization and message structure of Safe Time Layer(STL) and Safe Link Layer(SLL) combined with EN50159 safety standard.The safety communication of PROFIBUS is researched based on the ETCS Level STM. Some measures are also discussed to make sure the safety of PROFIBUS combined with the ETCS Level STM.In the paper, finally, PB-B-RS232 is adopted in PROFIBUS-DP to carry out safety communication.