本文将围绕以上问题展开论述，从控制系统的发展历程角度探讨现场总线的成因；阐述现场总线的概念、体系结构和特点给出现场总线的发展现状；提出面对现场总线百家争鸣的现状应采取的对策；结合具体实例说明现场总线开发应用方法。
二、现场总线的产生
纵观控制系统的发展史，不难发现，每一代新的控制系统推出都是针对老一代控制系统存在的缺陷而给出的解决方案，最终在用户需求和市场竞争两大外因的推动下占领市场的主导地位，现场总线和现场总线控制系统的产生也不例外。
1、模拟仪表控制系统
模拟仪表控制系统于六七十年代占主导地位。其显著缺点是：模拟信号精度低，易受干扰。data exchange between different systems.
can. The process control stage realizes various loop adjustments including complex control (various PID, ratio, Simith, etc.) and high-speed logic control.
Control, sequence control and batch intermittent control functions.
The internal communication of the process control station (between the controller and various intelligent devices such as I/0 or field instruments) adopts the international standard field controller.
Wire. The field controller supports various field buses such as Profibus. Profibus is the most widely used open field bus in the world.
Line international standard, divided into FMS, DP and PA three levels, DP communication rate can be as high as 12Mb. The CAN (DIN/IS011898 standard) bus
The biggest feature is its super sturdiness and data security. The system of course also supports Modbus. The communication with the intelligent field instrument is through
IART protocol or field bus (31. 25Kb ProfibusPA and FF bus).
The system communication between the operation management level and the process control level is realized by Di giNetS network (Industrial Ethernet/IEEE802.3 standard),
Users can choose the communication transmission medium (ordinary cable or optical fiber) and network
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