This paper describes a method of software synthesis for interlocking using safe PLC (programmable logic controller). An interlocking in railway signalling is the safe control device in order to operate many trains in the station and have to satisfy a fail safe. Traditional interlocking had been composed by the safe relays. At present it has been composed by the safe micro processors which is designed with the special purpose in the world.
Otherwise, the control devices in the European general industries has used the safe PLC (programmable logic controller) which developed to accept an EN standard. We suggest the interlocking system using the safe PLC.
We presents the advantages of the software system for signal input/output interface using a ‘standard block’ and the programming method to be able to achieve the standardization of interlocking logic with the matrix data. We made prototype interlocking and tested it. Therefore, we present the advantage of our method of software synthesis.