中文摘要现场总线是完全工业化的今天，用于沟通设备之间的联系的方法之一，是提高自动化信息管理水平的发展热点，用以改良当前设备使用繁复，实时性差的弊病。其中，ModBus总线作为全球第一个真正用于工业现场的总线协议，具有标准开放，帧格式简单紧凑且可支持多种电器接口等特点，逐渐被大多数个人与厂商采用，并逐渐成为产品标准配备。Modbus协议是一种在工业制造领域中得到广泛应用的网络协议，控制器相互之间通过此协议相互完成数据交流。它主要基于RS-485总线进行通信，实现微控制器之间及与其他设备之间的通信。本课题利用AT89C51单片机为控制核心，实现主机与四个从机之间通过基于RS-485的Modbus网络进行通信，实现数据采集与开关控制系统。前两个从机所连接的继电器由主机按键控制，其当前开关状态实时显示在主机系统中，而后两个从机各有两路A/D通道，其转换值也将不断刷新显示在主机系统中。32607
毕业论文关键词 ModBus协议 RS-485 主机 从机 信息交流
Abstract
Field bus is fully industrialized today, one of the methods which used for the connection between the communication equipment is to improve the automation development focus in the information management level, to improve the current equipment use heavy and complicated, the disadvantage of poor real-time performance. Among them, the ModBus bus as the world's first truly used in industrial field bus protocol, a standard open, simple and compact frame format and can support a variety of electric equipment interface etc., gradually adopted by most of the inpidual with the manufacturers, and gradually become a product standard. Modbus protocol is a widely used in industrial manufacturing network protocol, the controller by the agreement between each other to complete data communication. It is mainly based on RS - 485 bus communication, between microcontroller and the communication between with other equipment. This topic using AT89C51 as the control core, between the host and four from the machine through the Modbus network based on RS - 485 communication, data acquisition and switch control system. First two by the relay of the machine is connected from the host key control, the current switch state real-time display in the host system, and then two each have two lines of A/D channel from the machine, its conversion value will also continue to refresh the display in the host system.
Keyword field bus RS-485 host slave The data collection system
目次
1. 绪论 6
1.1 数据采集系统的研究背景及实际意义6
1.2 数据采集系统的历史及研究现状6
1.3 课题要求8
2. 相关基本原理介绍9
2.1 RS-485简介9
2.2 RS-485选取理由10
2.3 ModBus协议9
3. 总体电路的硬件实现13
3.1 硬件设计流程13
3.2 硬件设计注意事项13
3.3 AT89C51单片机介绍14
3.4 主机电路15
3.6 从机1、2电路16
3.7 从机3、4电路16
3.8 显示系统电路17
4 软件程序设计18
4.1 软件设计思路与功能模块18
4.2 ModBus主机模块程序18
4.3 ModBus从机1、2模块程序19
4.4 ModBus从机3、4模块程序22
4.5 基于ModBus协议的数据采集仿真24
4.6 基于ModBus协议的数据采集及控制系统仿真26
总结29
致谢30
附录一 参考文献31
1. 绪论
1.1 数据采集系统的研究背景及实际意义
为了满足工业要求和生产发展需要，现代工业中对设备的安全性与可靠性有着严格的要求，为了满足安全需要，用户往往需要实时性的，精确的，可靠的了解设备运行情况，以便对安全隐患进行排查和对突发情况第一时间予以解决。在整个安全环节中，对工业生产中各种实时数据的采集是最为重要，要求最为严格的一环，所以，对整个工业生产环境的各种数据进行实时的监控与传输就成为安全工程的重中之重。 基于基于Modbus总线的数据采集与控制系统的设计:http://www.youerw.com/tongxin/lunwen_29285.html