EM235,温度传感器,RS485通信.pdf

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摘要
在科学研究和生产实践的诸多领域中,温度控制占有极为重要的地位,特别是在
食品、大棚温室、冷金、化工、建材、机械、石油等工农业生产中具有举足轻重的作
用。随着电子及计算机技术的发展,出原来的简单逻辑量控制,逐步具备了算机控
制系统的功能,由于在计算能力、抗干扰能力、响应速度、通信联网能力、灵活性及
可维护性等方面的诸多优点,PLC在温度控制系统中得到了大量运用,本文设计了基
于PLC的多路温度采集系统。
在以PLC控制为核心的多路温度采集装置中,EM235将温度电压信号模拟量转
化为数字量,PLC将AD转化的数字量进行数据处理,然后通过RS485通信发给有单
片机组成的显示模块进行温度值的显示。
关键词:PLC,EM235,温度传感器,RS485通信
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Abstract
In the scientific research and production practice in many fields, Temperature contro
has very important position. Especially in food, awning greenhouse, metallurgy, chemical
industry, building materials, machinery, petroleum and other industrial and agricultural
production that plays an important role. Along with the development of electronic and
computer technology, by original simple logic quantity control, and gradually has the
computer control system of the function, because in the computing power, anti-interference
ability, response speed, communication networking ability, flexibility and maintainability,
and other aspects of the many other advantages, PLC in temperature control system got a lot
of use, this paper introduces the design of multi-channel based on PLC temperature
gathering system
In PLC control as the core of multi-channel temperature gathering device, temperature
voltage signal analogue into the digital quantity through the EM235. PLC is carries on th
data processing for the transformation of the digital by AD. And then by R$485
communication to a single chip microcomputer temperature display modules of the display
Key words: PLC, EM235, Temperature sensor, R$485 communications
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目录
1系统方案设计
1.1系统原理
1.2系统总体框图
1.3系统器件选择.
2系统硬件设计.
2.1概述
2.2PLC主机S7-226CPU.
2.2.1CPU结构.
2.,2.2CPU供电方式
2.2.3CPU226的性能参数
2.3EM235扩展模块.
2.3.1EM235的技术参数
2.3.2EM235模块接线.
2.3.3EM235模块设置.
2.3.4EM235模块的寻址
2.4温度信号的采集.
2.4.1Pt100铂电阻.
2.4.2铂热电阻测温原理.
2.4.3怛流源式测温电路..
5信号预处理.
2.5.1三种干扰的定义
16
2.5.2常用的抑制干扰措施.
2.5.3抑制自身干扰.
2.5.4抑制辐射干扰
...19
2.5.5抑制电源干扰抗.
2.6温度显示模块.
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2.6.1 Atmegal6单片机.
2.6.274HC595工作原理
2.7RS485通信
2.7.1RS485总线特点
21
2.7.2S7-200CPU通讯口.
..2
3系统软件设计
3.1程序流程图.
.23
3.1.1PLC主程序流程图.
3.1.2单片机主程序流程图.
3.,2数字滤波.
24
3.2.1常用数字滤波算法.
3.2.2平均值法滤波
3.3数据处理
27
3.3.1温度值算法.
27
3.3.2PLC地址分配.
27
环境温度采集子程序.
8
4结论.
致谢.
参考文献.
附录A温度采集原理图.
附录B显示模块原理图.
附录CPLC主程序梯形图.
36
附录D单片机程序清单.