Study On OPC Based Of Data Distribution Service Real Time System In DCS

In distributed control systems,due to different machines come from different manufacturers,and different manufacturers have different data standards,so a technology is needed to unify the data reading and writing standards,making it easier to obtain machine data.OPC is such a technology.It unifies the standards for reading and writing data in industrial field.But now,OPC technology is not enough in some areas to meet the development requirements of modern industry.Real-time data distribution technology is developed for modern military.It's a standard for data distribution and data subscription.Real-time data distribution technology is data-centric,based on the publish/subscribe model,for the purpose of data distribution,with high-speed.It's a good data distribution technology with some advanced features.OPC based of data distribution service real time system is a combination of OPC technology and real-time data distribution technology,which combines the advantages of these two technologies,and make up for each other's shortcomings.First of all,this paper studies real-time data distribution technology: The principle of real-time data distribution technology introduces the process of data publishing and subscription,the division of labor and collaboration of each participant;The publisher and subscriber chapters describe publishers and subscribers how to communicate and the relationship between publishers,subscribers and topics;The reliability calculation for data communication studies the reliability calculation formula;The data security chapter studies the data encryption and decryption process of data distribution technology,providing two encrypt algorithms for reference;The measurement method of real-time for data distribution shows how to calculate latency.The next study is the OPC technology: OPC data access principle chapter introduces OPC technology,OPC data structure and OPC data exchange principle;OPC interest-based filtering efficiency calculation chapter shows the calculation of math expectation and efficiency of data transmission times,and the efficiency is improved;The OPC alarm and event chapter introduces the principle of OPC alarm and event,event data structure,event transfer relationship;OPC network communication and it's testing chapter introduces the principle of OPC network communication,and OPC reading and writing for sync and async.The next study is OPC based data distribution service real time system: The topic combination chapter analyzes the data transmission process and the combination of themes;The theme combines before and after testing chapter shows the data for reading and writing speed of theme combination.The test proofs advantages of the combination;The data publish combined process chapter study the response time of data publish,and the combination process of data publish;The data publish combines before and after testing shows DataWriter concurrent response testing data and the advantages of combined data publishing.The data subscription combined process chapter analyzed the characteristics of data subscription and the process of data subscription combination.The data subscription combined before and after testing chapter combined data subscription before and and after for data subscription.The time after receiving the data was tested to give the advantage of combining data subscriptions.Finally,this paper study OPC based data distribution service real-time system programming design: Development system and development environment configuration chapter lists the system and environment configurations.The OPC theme settings analyzes the OPC theme parameters.The OPC functional design has programmed the OPC groups and OPC items and other OPC functions.The initialization design of OpenDDS is about the OpenDDS initialization program.The data publishing and data subscription design chapters are designed for publishers,subscribers,DataWriters,DataReaders,themes,data publisher,and data subscriptions.OPC based data distribution service real time system programming chapter combines OPC programming design and real-time data distribution programming design to complete the system program design of OPC based data distribution service real time system.