（论文 字数：22002页数：69）摘 要：在工、农业生产和日常生活中，各个环节都与温度紧密相联，温度的测量及控制占据着极其重要地位。温度已成为大多数仪器正常工作的前提，而且对温度的要求也越来越严格。因此，温度检测与控制方法的研究越来越受到人们的重视。
本文介绍了简易集散温度控制系统,系统为两层结构,上位机用组态王软件完成对下位机的监控。下位机利用数字温度传感器DS18B20 ,结合单片机组成传感器网络，设计了相关的硬件和软件，实现多点温度检测与控制。论文中介绍了使用DS18B20进行循环温度检测并对温度加以控制的方法，技术核心是通过单片机产生所需的时序对DS18B20进行温度读取控制。系统能对多个对象进行准确测量与控制，控制范围为室温至125℃，误差小于0.5℃。上位机PC与单片机之间的通信采用RS-485协议，由RS-485总线组成构成的分布式测控系统，具有设备简单、价格低廉、能进行长距离通信等优点。上位机组态软件KingView具有强大的数据采集、处理功能和友好的人机界面。基于组态王软件的多点远程温度测控系统,理想地实现了对相关设备的实时监测。
该系统具有成本低、可靠性高和使用方便等特点,可应用于仓库测温、楼宇空调控制和生产过程监控等领域。

关键词：DS18B20,单片机,温度控制,集散控制系统,组态王

Abstract ：In industrial and agricultural production and daily life, all sectors are closely related to temperature, Temperature Measurement and Control occupy a very important position. At present, temperature measurement and control equipment has become normal working majority of the premise that and the temperature requirements more stringent. Therefore, the temperature measurement and control method of attracting increasing attention.
The paper introduces a simple temperature distributed control system (DCS), the detection and control of the controlled objects are accomplished by slave computers, and the supervision of the controlled objects and slave computers is implemented in the host computer based on King View.DS18B20 type digital thermometer has the characteristic of one-wire bus. Using DS18B20 and Microprocessor AT89C51 build up sensor networks, which achieve the design of hardware and software for multiple spots temperature detected and control system. The main research topic is DS18B20 temperature cycle testing. The core technology was generated the DS18B20 timing through AT89S51 microprocessor to control DS18B20 read temperature. Conversion and read data through a unified AT89S51 microprocessor. Finally, the temperature was displayed by LED. The entire temperature detection and control system is capable of detecting and controlling multipoint temperature for accurate measurement, the controlling range from room temperature to 125℃, control error is less than 0.5℃.The communication between PC and microprocessor based on RS 485 is described in detail in the paper. The distributed monitor and controlling system which was constitutive of RS 485 bus, have some advantage, such as few equipment, low-cost, long distances communication and so on. King View software supports a powerful platform for real time detection project. It supports powerful function for data acquisition and management and man-machine interface. The real time state detection for temperature detected and control system based on King View software is designed to detect the devices and make sure the devices work in a reliable , effective and secure way.
With low cost, high reliability and convenience of operators, the system can be used in many fields such as the temperature measurement system of warehouse, the air conditioning control of building and the monitor of productive process.

Keywords: DS18B20; Microprocessor; Temperature control; DCS; King View

目 录

1 课题的现状及研究意义........................................2
1.1 课题现状 ............................................................2
1.2 研究意义 ............................................................2
1.3 课题要求 ............................................................2
2 方案论证 ...................................................4
2.1 集散温度控制系统工作原理 .............................................4
2.2 主要器件选型 .........................................................4
2.2.1 传感器 .............................................................4
2.2.2 主控单元 ...........................................................7
2.2.3 显示器件 ...........................................................7
2.2.4 控制模块 ...........................................................7
2.2.5 MAX485 .............................................................9
2.3 上位机组态监控 ......................................................11
2.4 系统总体设计框图 ....................................................11
3 硬件电路实现 ..............................................12
3.1 单片机最小系统 ......................................................12
3.2 DS18B20连接方式 .....................................................13
3.3 键盘和数码显示电路 ..................................................14
3.4 远距离通信电路 ......................................................17
3.5 控制电路 ............................................................18
4 软件设计 ..................................................19
4.1 概述 ..............................................................19
4.2 主程序 ......... ....................................................19
4.3 温度读取程序 ........................................................20
4.4 DS18B20初始化、读写程序 .............................................26
4.5 数码显示程序 ........................................................27
4.6 按键扫描程序 .......... .............................................28
4.8 控制程序 ... ........................................................31
4.9 组态王监控界面设计 ..................................................32
5 系统调试 ..................................................33
6 结论 ......................................................35
谢辞 .........................................................36
参考文献 .....................................................37
附录 ........................................................38

引言
目前,典型的温度测控系统是由模拟式温度传感器、A/D转换电路和单片机组成。自动化程度和可靠性较高,使用方便,得到了广泛应用。但是由于模拟式温度传感器输出为模拟信号,必须经过A/D转换环节获得数字信号后才能与单片机等微处理器接口,使得硬件电路结构复杂,成本较高。而以DS18B20为代表的新型单总线数字式温度传感器集温度测量和A/D转换于一体,直接输出数字量,与单片机接口几乎不需要外围元件,使得硬件电路结构简单,广泛使用于远距离、多节点的场合。具有较强的推广应用价值。
DCS是分散控制系统（Distributed Control System）的简称，国内一般习惯称为集散控制系统。它是一个由过程控制级和过程监控级组成的以通信网络为纽带的多级计算机系统，综合了计算机（Computer）、通讯（Communication）、显示（CRT）和控制（Control）等4C技术，其基本思想是分散控制、集中操作、分级管理、配置灵活、组态方便。DCS具有高可靠性、灵活性、易于维护等特点。本文将介绍一种基于DS18B20的典型温度集散控制系统。