Research On MQTT Intelligent Slave Technology For PAC Operation And Maintenance

In the new wave of industrial revolution,China put forward the "Made in China 2025" strategy based on national conditions,and vigorously promoted the development of manufacturing in the direction of informationization and intelligence.For the Programmable Automation Controller,which is widely used in the industrial control field,the information operation and maintenance puts forward higher requirements.The PAC system needs to expand the built-in functions to provide operation and maintenance services for users and developers.In particular,an online upgrade service should be provided to meet the needs of developers for remote program development and upgrades,but the current research on this issue is still in its infancy.This paper proposes a standardized intelligent slave scheme to expand the functions of the PAC system,and focuses on an online upgrade service technology of the PAC system.It is determined that the domestically-programmed full-programmable chip and the wireless communication module are used as the hardware basis,and the CANopen bus and the Message Queuing Telemetry Transport protocol are used as the communication scheme to block the data and stop waiting.The protocol and verification mechanism are the overall scheme of the reliable transmission scheme.The design of the MQTT cloud service and the data communication between the slave and the server are studied.Cloud platform design,including data sharing services,codec services,verification services,and file transfer services,using cloud services,open source messaging middleware,and scripting modules;modular design approach for slave application layers,including purely logical component platforms The module and the MQTT publish/subscribe module enable data communication with the cloud platform.The online upgrade service of PAC system based on bus process data object is studied.The CANopen protocol stack is integrated for the slave station,and the CANopen communication module is added at the application layer to realize the communication between the master and the slave.On the basis of this,the bus process data object,the master station data communication interface and the slave object dictionary interface are utilized.The master-slave data interaction is realized;the timeout retransmissionmechanism is added,and the online upgrade process of the PAC system is analyzed and designed.According to the research results,the experimental platform was built,and the communication performance of MQTT intelligent slave station was tested.The design experiment verified and analyzed the online upgrade technology of the designed PAC system.The experimental results show that the MQTT intelligent slave station has good performance and extended PAC.The system's online upgrade service technology is feasible and effective.