Research And Implementation Of The Key Technology Of PLC Interconnection In Digital Workshop

With the arrival of industry 4.0 era,more and more traditional industries are moving towards digitalization,among which digital production workshop has become an important part of plant construction.Through the use of network interconnection,plant equipment and systems can be automated,thus promoting the development of traditional industries.However,due to the differences of equipment suppliers,equipment types and automation levels,industrial field equipment has a variety of hardware interfaces and communication protocols,which increases the difficulty of interconnection between digital workshop equipment.Based on the above problems,combined with the current situation of the industrial Internet at home and abroad and the research progress in the field of industrial control PLC,this paper designs a solution to the current requirements of the industrial digital workshop interconnection,and proposes a key technology of the interconnection between the digital workshop equipment,which includes four modules: Based on the field level equipment data collection module,serial / network multi protocol Communication module,embedded device with OPC UA server and OPC UA client based on WCF framework.In the data acquisition module,firstly,the frame structure and communication process of Modbus RTU / TCP and PROFIBUS DP are analyzed,and the master / slave program of the protocol is implemented on PLC and server respectively by using ladder diagram and C language.The principal component analysis(PCA)algorithm compiled by Matlab is used to reduce the original ten feature attributes into seven attributes with low correlation,including protocol frame length,function code,function code length,flag bit,device address,register address and check bit check mode.Then,based on the above seven features,C5.0 algorithm and the random Sen solving C5.0 over fitting problem are used Forest algorithm completes the identification program of serial / network port multi protocol communication protocol frame on the server,and the accuracy of classification and prediction can reach 91%.Next,we use UA ANSI C protocol stack to build OPC UA server on the embedded device with limited memory and low processing capacity,and complete the process of address space configuration,request / response service,information security policy configuration and node communication,realize the real-time data collection and saving of field level equipment,and transmit the data to the upper computer OPC through a unified interface UA client,which completes data visualization,storage and provides the basis for the next step of analysis;finally,based on WCF framework,OPC UA client is built.WCF framework has good heterogeneity,openness,security and scalability,which meets the requirements of obtaining real-time operation parameters of industrial production equipment and remote monitoring of real-time operation of industrial equipment.The client has the functions of data reading / writing,monitoring / subscribing data items,data visualization,etc.And connect with Oracle database.In the end of this paper,the experimental process is verified and tested,including functional test and performance test.Through the preparation of functional test cases,the hardware interface connection and data message transmission process test of the equipment configuration module are completed;the driver configuration and program running test of the data acquisition module;the protocol frame identification,node configuration management,network parameter configuration and OPC UA server operation process test of the OPC UA server module;and OPC WCF application operation,client function operation,monitoring / subscription function and TCP connection test of UA client.In the end of this paper,the experimental process is verified and tested,including functional test and performance test.Through the preparation of functional test cases,the equipment configuration module test is completed;the driver configuration and program running test of data collection module;OPC UA server operation process test;and OPC UA client test.Finally,the performance indexes of the whole key technology platform,such as automatic operation,stability and pressure,are tested.The test results are normal,and the performance meets the current needs of the digital workshop.