Ethernet-based Network Control Terminal Design And Realization

Network control is the objective needs of a complex control system and the remote control system. the intelligent of Sensors, actuators and drives provides the necessary material base of deeper application to communication network in control system and development of High-speed Ethernet and fieldbus technology solved reliability and open questions to the networked control system. In order to achieve network control,it is necessary to exploit a control terminal between the controlled object and the host,so that the controlled object can access to the network,and be controled remotely by the host through the network.In this paper,atmega128 MCU is used as the core to exploid the network control terminal.The design includes atmega128 MCU interface circuits,RTL8019AS network chips circuits,RS-232 interface circuits, analog input and output hardware.RTL8019 chip driver, ADC drivers, serial port communication driver and the system main program are exploided.The embedded operating system NUT / OS is ported to atmega128 MCU to achieve NUT / NET protocol stack and MODBUS / TCP protocol between the host and control terminal.Finally,the TCP connection with the control terminal is established on the host with VB6.0,to achieve the temperature control network with temperature controling experimental box. MODBUS / TCP protocol frame format is used in the communication between the host and the control terminal.The availability of the control terminal is vertified by the the temperature control experiment .