Research On The Secure Communication Technology Of The Upper And Lower Computer In Domestic PLC

With the rapid development of industrialization and information,the integration of traditional industrial control system and enterprise management system is getting higher and higher,and ensuing security problems are becoming more serious.In recent years,a large number of attacks on industrial control systems broken out at home and abroad,which gave our industrial safety sounded the alarm.As an important part of industrial control system,Programmable Logic Controller is one of the three carriages to drive the development of industry.However,the current domestic market share of 90% of the PLC is monopolized by foreign manufacturers,the security of the core infrastructure related to the people's livelihood can't be guaranteed.With the "Two Fusion" and "Internet Plus" strategy to promote,the industrial control network is more open,and the PLC control system is facing more severe security situation.Therefore,the development and research of independent and controllable PLC products and the corresponding control software,and the study of PLC security communication technology are the key to control the safety of critical infrastructure.Based on the research and development of the domestic PLC product,this thesis analyzes the running principle and mechanism of the PLC communication module,and studies the standard of information security evaluation of industrial control system IEC62443.In view of the threats faced by all aspects of communication between PLC and host computer,the corresponding safety measures are put forward according to the evaluation standard,and the communication interface of the PLC controller is designed and developed with the requirements of intrinsically safe.Based on the domestic hardware and software platform of the upper and lower machine,the safety mechanism is applied to the communication system development of the upper and lower machine,testing to verify its security.The main contents of the thesis include the following aspects:1)Introduce the information security situation of industrial control system in the era of "Two Fusion" and the application of PLC in industrial control system,and explain the research status and related policies and standards of PLC control system security both at home and abroad.2)Describe the working principle and function of each level equipment in the industrial control system,and analyze the threats and hidden dangers of the host computer(configuration software,monitoring software),the lower computer(PLC)and the topology of the transmission network and the communication protocol.These threats and hidden dangers indicate that the source of information security in industrial control systems is the lack of essential security and provide reference for the development of the national production of PLC control system and its safe communication mechanism;3)Design the upper and lower machine structure of the national PLC control system,and describe the upper and lower machine system platform,based on the domestic CPU platform to develop communication interface(network port and serial port)driver,and based on industrial control system information security standards IEC62443 design security communication Model,analysis and design the communication specialized protocol and common protocol of the upper and lower machine,study the communication security mechanism,and describe the principles of communication encryption and security analysis;4)Based on the platform of the nationalized upper and lower computer system,design and develop the specialized communication system for PLC and the programming software and the common communication system for PLC and monitoring software,and in the dedicated communication system to achieve the independent design Communication protocol and security mechanism,in the general communication system to achieve Modbus/TCP protocol,and explain the communication module function design and implementation process of host computer programming software “Pro Sys”.5)Build a test environment to complete the design of the communication system for functional testing.The results show that the proposed safety communication technology designed to meet the relevant security needs and has been used in the N series PLC products of laboratory.PLC control system is now widely used in the field of industrial control.We should design and develop the national production of the PLC control system,research the safety communication mechanism between upper and lower computer,and use these research findings in domestic PLC products to explore development direction for domestic PLC control system information security,but also help improving the safety of national Industrial Control System in the Internet.