皖西学院本科论文（设计）
基于PLC温室温度检测与控制系统的设计
作 者 指导教师
摘要：温度检测和控制对人类日常生活、工业生产、气象预报、物资仓储等都起着极其重要的作用。在许多场合，及时准确获得目标的温度信息是十分重要的，近年来，温度测控领域发展迅速，并且随着数字技术的发展，温度的测控芯片也相应的登上历史的舞台，能够在工业、农业等各领域中广泛使用。
本系统是通过温度传感器采集温度数据，利用温度测量与温度控制相关理论知识设计的PLC温控系统。运用PLC设计温室温度测控系统，从自动化运行的角度出发，分析讨论其产生故障的可能原因。同时从实际硬件电路出发，分析电路的工作原理，根据设计具体情况提出修改方案和解决办法。我所使用的温度传感器是XP-TP-A-V010-D，它具有体积小，精度高和功耗低等特点。温度传感器采集到的温度数据是模拟信号，因此在系统中，我将PLC增加了一个模拟量扩展模块EM235,采集到的温度信号便能通过该模块直接输入到PLC中，PLC则对数据进行分析、处理，并通过执行部件对温度进行控制，这种自动化、智能化的处理方式在温室温度检控系统中将有着无限的应用和发展空间。 关键字：PLC，温度传感器，检测,控制
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Design of detection and control system of greenhouse temperature
based on PLC
Abstract: Temperature measurement and control plays an extremely important role in human daily life, including industrial production, weather forecast, material storage, etc.. In many cases, it is very important to acquire the timely and accurate information of the temperature of the targets. Recently, along with the development of digital technology, the rapid development of temperature measurement and control has been widely used in various industrial agricultural fields, meanwhile, the chips of measurement and control the temperature have been on the historical stage. This system, by collecting temperature data through the temperature sensor, with the application of PLC control system based on the theoretical knowledge about temperature measurement and control, intends to analyze the potential causes of the breakdowns in their automatic operation. At the same time, starting from the circuits of actual hardware, and via analyzing operating principles of these electric circuits, this system is aiming at putting forward the revising proposasl and solutions according to the specific situations. The temperature sensor used by the author is XP-TP-A-V010-D, which is distinguished with small size, high precision and low power consumption. The temperature data collected by the temperature sensor is an analog signal. Therefore, in the system, an analog extended module of EM235.I will be added to the PLC so that temperature signal collected by
皖西学院本科论文（设计）
the module can be directly input to PLC, and PLC will analyze, process the data, and control the temperature through regulating the components. This kind of automatic and intelligent disposure will be definitely in infinite application and tremendous development in the temperature controlling system in the greenhouse. Keyword: PLC, Temperature sensors, Detection, Control
皖西学院本科论文（设计）
目录
1.绪论 ............................................................. 1 2.系统总体设计方案 ................................................. 2
2.1.总体方案 ................................................... 2 2.2.系统硬件连接图 ............................................. 4 3.可编程逻辑器件（PLC） ............................................ 5
3.1.PLC的定义 .................................................. 5 3.2.PLC的分类 .................................................. 5 3.3.PLC的基本结构 .............................................. 5 3.4 .PLC的工作原理 ............................................. 6 3.5. PLC主要厂家及西门子S7—200 ............................... 7 4.温度传感器 ....................................................... 9
4.1.温度传感器的分类 ........................................... 9 4.2.温度变送器 ................................................. 11 5.硬件设备与电路图 ................................................ 12
5.1.控制系统的I/O点及地址分配 ................................ 12 5.2.状态灯、扬声器、暖风机电路 ................................ 13 5.3.温度采集电路 .............................................. 13 5.4.EM235模拟量输入电路 ....................................... 14 6.主程序及梯形图 .................................................. 15
6.1.主程序OB1 ................................................. 15 6.2.子程序0，取实际温度变量 ................................... 19 7.结论 ............................................................ 21 致谢 .............................................................. 22 参考文献 .......................................................... 23