Research And Design Of Safety Controller Based On Dual CPU Architecture

For the key control in some special industrial fields,conventional PLC,due to its own system structure and other problems,has no corresponding mechanism to deal with when there is a fault or error in the implementation process,which affects the safety of industrial production and may even cause serious consequences.At present,safety PLC,as a general safety controller,plays a more and more important role in the field of safety control.Firstly,this paper introduces the research background and research status at home and abroad.In this paper,based on the analysis of several common safety PLC structures and relying on the "Shanke intelligence" conventional PLC platform,a safety PLC structure model based on double redundancy error tolerance system is proposed,and on this basis,the software and hardware system design is carried out.The hardware terminal of safety PLC adopts modularization design.This paper designs motherboard,main control module,safety I/O module,multilevel power module,communication system and so on.The main control module and the safety I/O module are designed with dual CPU architecture,and two interaction channels are designed between the main control modules,which are respectively used for "data voting" and "heartbeat signal" detection.The safety I/O module has 8 channels of safety input/output,the input acquisition channel has "self detection",and the output execution channel has "data feedback".Safety PLC monitoring program is responsible for PLC logic control and real-time monitoring.The monitoring program consists of three parts: the main control module monitoring program,the safety input module monitoring program and the safety output module monitoring program,which realizes the functions of system initialization,safety input collection,user program analysis,safety output execution,etc.The system realizes PLC safety control function through safety mechanism.Based on the analysis of the safe PLC working mode,this paper proposes a master-slave competitive system synchronization mechanism based on the task cycle,and reduces the deviation of the master-slave channel operation through the delay deviation compensation algorithm to ensure the system synchronous operation.In order to further improve the system availability and improve the data voting mechanism,a voting mechanism with a certain system margin time is proposed.At the same time,data verification mechanism and system diagnosis mechanism are used to further ensure the system security.In the laboratory environment,the software and hardware of the system are tested,and the results show that the safety PLC can guarantee the synchronous,safe and stable operation of the dual channel system.Finally,the reliability block diagram is used to analyze the hardware safety integrity of the main control module.