Application of IEC60870-5-104 protocol in the SCADA system of the 1st Shanxxi-Beijing Gas Transmission Pipeline

During the consolidation of SCADA system for the 1st Shanxi-Beijing Gas Transmission Pipeline, IEC60870-5-104 protocol based on TCP/IP has been applied to substitute the original communication mode of Modbus serial protocol.The key points in IEC implementation is that IEC protocol between master and sub stations is based on the reliable TCP connection; the TCP connection is initialized by the master station (client), and then accepted by the sub station (server); the both sides use the fixed 2404 TCP port the acknowledged IP addresses of the server and client are regarded as the basis for connection; under the condition of no requests from the client but it is indeed changed in the server, the data will be sent initiatively by the server.Based on the analysis of data flow and data response time in comparing the old station control system used Modbus protocol to the reconstructed station control system used IEC 104 protocol, it is proposed that application of IEC 104 protocol based on network between station and control center has such a great advantages such as real time, high reliability, large data throughput, easy extension, report by exception, network transferring, data with timestamp, etc.