Fieldbus And Industrial Ethernet-based Field Intelligent Control Unit

Fieldbus is one of the active topics of the current technical development in automatic field, which is whole scattered, intelligent, bidirectional, interconnected, multivariable and multipoint communication network is used between local meter, control system and control room. PROFIBUS is an open bus standard, which can be applied spreadly in many aspects such as manufacturing industry, procedure industry and building automation. In addition, PROFIBUS-DP is applied mainly in high-speed transmission among local devices. The cycle transmission is performed through high-speed serial bus among MCU and local devices (such as I/O, drivers, valves etc.). Industrial Ethernet has many advantages such as applying widely, lower price, high baudrate, etc., which can be applied in resource manage layer and manufactur layer of the industrial total automatic system.With the development of computer, communication and control, a deep technique change is taking place in control domain. Control system is developing towards the signal digital, control intelligent, communication network open system. Fieldbus and Industrial Ethernet are more and more widely applied in industy control area, but they both have disadvantages. Therefore, how to amalgamate their advantages to make them up will be a new direction in control area.Under this background, making use of the openness of network protocol, on the base of analysing the protocol theory and realization of PROFIBUS-DP and industrial Ethernet, this task designs a locate intelligent measurement and control unit, which integrates the advantages of PROFIBUS-DP and industrial Ethernet to fulfill the technic requirement of locate instruments among the new network control system. The measurement and control unit uses blocking structure, the power supply, main control block and other function blocks are relatively separate, connected and combined via motherboard, and support the plug and play function. Main control block uses Siemens PROFIBUS Controller (SPC3) to design PROFIBUS-DP interface, which can be connected to standard PROFIBUS-DP control network; uses Ethernet controller RTL8019AS to design Ethernet communication interface, following standard TCP/IP protocol. Measurement and control unit communicates with system and function blocks, the communication structure of which uses popular All-In-One mode. Furthermore, main control block can make optimize control of measurement and control unit according the effect data of each function block, so it gives prominence to centralized control function, and make perfect the centralized...