Research On Hot Standby Soft PLC Runtime System Based On Domestic SoC And Fieldbus

PLC has become increasingly important in China's national economy.Only the core technologies of PLC are really mastered,China's intelligent manufacturing industry can be competitive,and equipment manufacturing can get a qualitative improvement.Based on domestic full programmable SoC,domestic real-time Ethernet bus NCUC2.0,this article researches on the runtime system of domestic soft PLC fully compliant with IEC 61131-3 standard,which includes single CPU system based on fieldbus and double CPU system with redundancy according to the difference of target applications.The main contents are as follows:Firstly,the single CPU system based on fieldbus is studied.Based on the domestic NCUC2.0 bus,the bus application layer of the soft PLC runtime system is constructed: channel access,distributed clock synchronization and other reliability protection technology of NCUC2.0 are analyzed,and the application layer scheme CoN based on NCUC2.0 is proposed and realized,then a method of object dictionary automatic configuration is proposed for master and slave stations,thus enabling the automatic and efficient configuration of hybrid reconfigurable slaves.The runtime system of single CPU system is achieved on the domestic fully programmable SoC: adopting the master-slave structure with fieldbus communication,the CANopen application layer is implemented in the master and slave respectively,and the master can communicate with the interface monitoring software by the Modbus protocol,then the I/O and motor control are implemented on the slave by FPGA.The single CPU system has been productized and has been used in engineering applications.Secondly,double CPU system with redundancy and fault-tolerance is studied.After analysis and comparison of common redundancy types and dual PLC synchronization methods,a hot-standby scheme based on task scheduling is proposed,and the scheme is verified using the formal validation tool UPPAAL based on Time State Machine Theory.Then the overall redundancy architecture is designed on domestic full programmable SoC: the main logical task and backup task which are isolated from each other are designed on ARM,the transparent error detection,site preservation and status synchronization are achieved in the backup task,and the status synchronization,process data cache,CAN and Ethernet link control are realized on FPGA.Finally,the validity of the synchronization method is verified by experiments,and some of the key performance indicators of the redundant system are measured.In short,based on the domestic technologies,the paper has taken a solid step forward towards autonomous and controllable industrial control system.