摘 要
在传统的DCS控制系统中,模拟信号的传输均采用一对一的连接方式,因而整个系统的结构十分庞杂,成本高。而且抗干扰能力低,故障率高。近几年,随着计算机及网络技术的发展,现场总线控制系统FCS(Fieldbus Control System)在工业各领域中得到广泛的应用。
本文以目前国际上广受关注的CAN总线为基础,设计了基于CAN总线的纸浆浓度智能测控系统的设计。以改进传统DCS控制系统的不足,改善纸浆浓度测控中测控的性能。本系统具有结构简单,控制精度高,抗干扰能力强,性价比高,有突出的可靠性,实时性和灵活性等优点。
论文首先对现场总线做了初步简介,简单介绍了目前国际上主流的现场总线,并详细介绍了CAN总线的性能特点。然后简单阐述了造纸的基本工艺,浓度控制机理以及目前浓度测控系统技术发展的现状。接着对控制方案进行了分析,并与传统的DCS控制系统进行了比较。然后讨论了下位智能测控节点和上位机的设计,并对各模块电路以及软件进行设计,列出了部分系统软件程序框图以及SJA1000初始化程序、发送程序和接收程序。之后论文对控制算法进行了设计,并对PID参数进行了整定。
关键词:CAN总线 纸浆浓度测控 测控节点 AT89C55
Abstract
In the traditional DCS controlling system, the transmission of analog signals always adopts an one to one connecting manner, therefore, the structure of the whole system is quite huge and complicated, with high cost. Moreover, its capacity of resisting disturbance is quite low and the fault rate is quite high. In recent years, as the development of computer and Network technology, Field bus Control System is being widely used in the various industrious fields. This paper bases on the CAN Bus which draws wide attention internationally recently, studying the design of the paper pulp measuring and controlling system, in order to improve the weak points of traditional DCS controlling system and controlling capability in paper pulp measuring and controlling. This system has many advantages, such as simple structure, high controlling precision, strong capability of resisting disturbance, high cost performance, outstanding reliability, instantaneity, flexibility and so on.
This paper firstly offers an brief introduction of Profibus, stating the mainstream Profibus in the world and introducing the capability and characters of CAN Bus in detail. Then it expatiates the basic paper making craft, the mechanism of thickness controlling and the technological developing status of recent thickness controlling system. After that, it analyzes the controlling schemes and compares them with the traditional DCS controlling system. Finally it discusses the design of spot Intelligent Measurement and Control nodes and designs all kinds of modular circuit and software,Listing the framework of part system software procedure and initializing, senging, reciving procedure of the SJA1000.Then this paper sets the parameters of PID algorithm.
Key word:CAN field bus;Paper Pulp Thickness Measuring and Controlling;Measuring and Controlling node;AT89C55