Ethernet-based Process Control Platform

As an emerging technology of industrial control field, the Industrial Ethernet is becoming the mainstream technology of industrial control network. The Field Bus, as an important present industrial control technology, will also play an important role in the future. The experimental teaching in universities particular emphasis on software programming and algorithm simulation, but lack of necessary control system and experimental object, so it is cannot follow the development of automation technology. In this paper, we set up a process control platform that combines the Field Bus and Industrial Ethernet technology. The platform is a seamless integration automation network system; it not only follows the development of industrial automation technology, but also provides the research object and experimental environment, so it can well meet the universities teaching requirements.The process control platform uses three groups of Rockwell industrial control system, which consist of three large-scale process control device sets: experimental water tank, distillation column and boiler. In communications, the NetLinx forms by information network of Ethernet/IP, control network of ControlNet, device network DevcieNet, which is a three layer network system. The hardware system of the platform adopts CompactLogix, ControlLogix series control system, and equip assistant devices of power supply, relay, cycle power regulator and so on. Through the layout design, hardware connection and function debug, we found three consoles, which matching with the three process control devices. The control software of the lower computer adopts modularization design, the function of every part is clear and attach annotate. The software handles the range selection, data format selection and numerical transformation of all the input and output nodes, and accomplish the planning of ControlNet and DeviceNet. The monitor software of upper computer matches with the lower computer software, it fulfill the function of real time display field condition, trend chart, data save, alarm summary, helps and so on, it also provides the experimental system introduction and system parameters setting. The software provides four algorithms of PID control, fuzzy control, fuzzy PID control and predictive control, and also have other controls and field control, convenient for self programming and teaching demo, the users can freely select control algorithms and control object, so it strong support the experimental teaching.At present, the remote experiment that based on industrial control system, can only monitor and can not control, the users is equivalent the monitor, the effect of the experiment is not well. In this paper, we first present the new idea that combine VPN (Virtual Private Network) technology and industrial control technology. VPN is a rapidly developmental internet technology, through encryption and date encapsulation, it establish an safe and steady connection tunnel in the chaos public internet, the VPN can carry out exchange visits between different networks. The import of the VPN technology, can real solve the remote control problem in the industrial control. This paper uses the existence technologies, implement the control of experiment object of laboratory LAN from dormitory, it prove the feasibility of the VPN technology.