Design And Implementation Of Soft-PLC Runtime System For Industrial Robots

In recent years,with the development of science and technology,information technology is profoundly changing the form of industrial manufacturing.PLC(programmable logic controller)is a digital logic controller for automatic control,which is widely used in the field of industrial control.Limited by the lack of openness and poor scalability of the traditional PLC architecture,soft PLC technology has become a new development direction in recent years.The soft PLC system is divided into two parts: the development system and the runtime system.The runtime system is the key to ensure the correct operation of the user program.The research goal of this thesis is to design a soft PLC runtime system that can run user programs that comply with the IEC61131-3 standard.This thesis introduces the research significance of soft PLC technology and investigates the research status of soft PLC and its runtime system in the world.At present,most of the soft PLC systems independently developed in China only support a single language,and the support for the IEC61131-3 standard is insufficient.There is a big gap compared with similar foreign products.After that,the specification of the IEC61131-3 standard for user program operation is introduced,and the requirements analysis and overall design of the soft PLC runtime system are carried out.The runtime system is responsible for loading and starting the user program and providing the necessary environment for the running of the user program.This thesis introduces the running mechanism of the runtime system,adopting the way of compiling and executing and decoupling the runtime system from the user program,designing and realizing the four modules of the runtime system: task scheduling,device interaction,daemon node and data monitoring.The task scheduling module supports the execution of tasks in the user program through non-preemptive scheduling or preemptive scheduling;the device interaction module supports the interaction between the user program and the device I/O interface,shields device details for the user program,and also supports virtual IO devices;The daemon node can easily remotely deploy and remotely start the user program;the data monitoring module can monitor the status of the internal variables of the user program,which is convenient for debugging and monitoring of the running status.Finally,write several PLC user programs to test the runtime system using virtual IO devices and actual devices to prove the validity of the runtime system.