大气环境参数数据采集系统

电气自动化论文编号:ZD603 论文字数:20923,页数:46，有外文翻译，原理图，

 目 录

第1章  绪 论 1
1.1 大气环境监测目的 1
1.2 大气环境相关资料 1
1.2.1 污染源分布与排放情况 1
1.2.2 气象资料 1
1.2.3 地形资料 1
1.2.4 土地利用和功能分区情况 2
1.2.5 环境标准参数的说明 2
1.2.6 监测 4
1.3 系统初步设计 6
1.3.1 系统硬件初步选择 6
1.3.2 硬件部分组成 7
1.3.3 软件部分组成 7
1.4本章小结 8
第2章 传感器 9
2.1 传感器基本概念 9
2.1.1 传感器的定义 9
2.1.2 常用传感器的组成分类 9
2.1.3 传感器基本特性 10
2.1.4 气敏传感器的分类介绍 10
2.2 大气监测系统中的传感器 12
2.2.1 CO传感器 12
2.2.2 SO2传感器 12
2.2.3 NOx传感器 13
2.3 传感器信号的处理 13
2.3.1 保证工作电压区间 13
2.3.2 交叉敏感性和温度相关效应的克服 13
2.3.3 信号放大电路 14
2.4 本章小结 16
第3章 A/D转换器及其接口电路 17
3.1  A/D转换器的选择 17
3.1.1 选择的意义 17
3.1.2 选择的因素 17
3.2  A/D转换器的应用 18
3.2.1 仪表应用 18
3.2.2 通信应用 19
3.2.3  ADC0809的结构及性能 19
3.2.4  AD574A转换器的结构及性能 22
3.2.5 输入与接口 25
3.3  A/D转换器接口电路 26
3.3.1  A/D转换器与前端接口电路 26
3.3.2  多路模拟开关CD4051 26
3.3.3  8051单片机的结构及性能 28
3.3.4  AD574A与8051单片机的接口电路设计 30
3.4 本章小结 32
第4章  远程通讯系统 33
4.1 串行通信的硬件电路设计 33
4.1.1  硬件及其连接 33
4.1.2  RS232/485双向转换 34
4、2 串行通讯的软件设计 36
4.2.1  MCS-51多机通信约定 36
4.2.2  MCS-51多级通信系统程序设计 38
4.3  本章小结 42
参考文献 43
致 谢 44

摘 要
 
 大气品质的需求在不断的提高，作为城市环境质量的重要组成部分，大气环境的质量好坏直接影响到了在这个城市中生活的人群的生存环境和健康状况，有必要在这样的大城市建立符合国家规范的大气监测系统。
 本文根据大气环境监测标准，设计了一种较为先进的环境监测控制系统，并从硬件、软件加以实现。该控制系统由1台PC机作为主机机，多台MCS-51系列单片机并辅以适当的外围电路和存储器单元作为从机机组成。在系统功能的分配上，主，从机可并行工作，提高了系统的可靠性。同时，对本监测系统所采用的传感器的原理以及功能做了详细的介绍，对传感器的外围电路以及工作原理做了深入的说明。详细说明了ADC0809和AD574A的结构和性能，并在本系统中选择后者。最后，介绍了AD574A与8051单片机接口电路设计及软件程序设计。
 PC机一般都配有串行RS232接口，但其数据传输距离短，速度慢，抗干扰能力弱；而串行RS485接口，数据传输距离长，抗干扰能力强。所以本系统采用RS485接口。要实现上、下位机的通信，必须进行RS232与RS485信号电平转换，这就要借助于RS232与RS485的串行通信转换电路。
 本文也给出了数据采集系统的电路图以及各个通信模块的程序流程图，经过模拟运行，该监测系统具有这样的优点：电路结构简单；智能化程度高；它可以将大气中的环境因子准确的采集；整个通信系统抗干扰能力强。
 
关键词：环境监测，传感器，单片机，AD574A，RS485
  
 

 ABSTRACT
 Air quality in the demand for continuous improvement, urban environmental quality as an important component of the atmospheric environment have a direct impact on the quality to life in this city in the crowd of the living environment and health status, it is necessary to establish such a large cities Consistent with national norms in atmospheric monitoring system.
 Based on the atmospheric environment monitoring standards, design a more advanced environmental monitoring control system, and from the hardware and software to achieve. The control system consists of a Taiwanese PC as a host machine, multiple MCS-51 series SCM supplemented by appropriate external circuit and a memory unit from the machine components. In the distribution system, Lord, from the machine can be parallel efforts to enhance the reliability of the system.At the same time, the monitoring system used by the sensor and the principle of functional done a detailed account of the external sensor circuit and principle to do an in-depth description. A detailed description of ADC0809 and AD574A the structure and performance of the system and choose the latter. Finally, on the AD574A and 8051 microcontroller interface circuit design and software design.
 PC-general are equipped with RS232 serial interface, but its short-distance data transmission, slow, weak anti-interference capability, and Serial RS485 interfaces, long distance data transmission, anti-jamming ability. Therefore, this system uses RS485 interfaces. To achieve the upper and lower crew communications, the need for RS232 and RS485 signal conversion, which will help the RS232 and RS485 serial communication conversion circuit.
 This paper also presented data acquisition system and various communication module circuit the process flow chart, after simulation run, the monitoring system has such advantages: a simple circuit structure; highly intelligent and it can be environmental factors in the atmosphere accurate Acquisition; entire communication system strong anti-interference capability.
 
Key words: environmental monitoring, sensors, SCM, AD574A, RS485