毕业设计
基于触摸屏与PLC实现的
果蔬保鲜库温、湿度监控系统设计
姓 名： 沈 磊 学 号： 07010007 班 级： 07自动化1 专 业： 自动化 所在系： 自动化工程系 指导老师： 郭 丹
基于触摸屏与PLC实现的
果蔬保鲜库温、湿度监控系统设计
摘 要
随着科学技术的进一步发展，人们对果蔬的质量的需求进一步提高。果蔬保鲜库的储藏环境的要求进一步提高，对果蔬保鲜库的温、湿度监控就显得尤为重要，这是保证果蔬的口感和质量的重要因素之一。其主要的内容是保鲜，即较长时间内，最大限度地保持一些农产品原有的品质和新鲜度，就是鲜活的农产品，在保鲜贮藏一段时间后，仍然是刚采摘或接近刚采摘时的鲜活状态和品质。水果保鲜库贮藏是抑制微生物和酶的活性，延长水果蔬菜长存期的一种贮藏方式。保鲜冷库技术是现代水果蔬菜低温保鲜的主要方式。
本设计是以触摸屏和PLC为基础，实现果蔬保鲜库的温、湿度监控系统的设计。控制系统以可编程控制器为控制核心，以触摸屏为人机接口，使系统控制界面友好，简单直观，便于操作。用户可通过键盘设置需要的温、湿度值以及报警的上下限值,通过人机界面即时显示。
本设计主要应用可编程控制器和触摸屏为主要装置，该装置具有可靠性高，抗干扰能力强，适用性广等特点，不仅可以用于果蔬保鲜库的监控设计，也能用于其他控制系统或者监控系统的设计。
关键词：PLC 触摸屏 温度 湿度
Control System Design of Fruits and Vegetables Freshness Storehouse Humidity and Temperature Monitoring Based on Touch Screen and PLC
ABSTRACT
With the further development of science and technology, the fruits of quality
requirements have further improved. fruits keep the library for the storage of environmental needs further improvement in fruits keep the storehouse the temperature or humidity monitoring is particularly important that this is that the fruits of quality and a key factor. The main contents, which is kept a long time, the maximum number of agricultural products in the quality and fresh, as fresh produce, keep up after a time, is still just picked at or near just picked the personal status and quality. fresh fruit is free from the library to store and enzyme activity, the fruits and vegetables remain issue of a store. keep in cold storage technology is a modern fruits and vegetables fresh approach.
This design is based on the screen and the plc and fruits keep the storehouse the temperature or humidity monitoring system. control system design in a programmable controller to control key to the screen for the man-machine interface, the system of control interface and simple, straightforward, easy operation. users can set the keyboard of temperature or humidity as well as the value of the values of the interface displayed.
This design main applications programmable controller and the screen is the main, the device with high reliability, strong anti-jamming capability, wide applicability characteristics, not only can be used in fruits keep the storehouse the monitoring of the design, can be applied to other control system, or monitoring system design.
Key Words：PLC Touch screen Temperature Humidity
目 录
第一章 绪论???????????????????????????????1
1.1选题的意义和目的???????????????????????????1 1.2国内外的发展趋势???????????????????????????1 1.3主要的设计任务????????????????????????????2
第二章 保鲜库温、湿度自动控制的原理??????????????????3
2.1温、湿度的相关知识??????????????????????????3
2.1.1湿空气?????????????????????????????3 2.1.2湿空气的状态参数????????????????????????3 2.1.3热空气的基本热力学过程?????????????????????4 2.2温、湿度控制的基本原理????????????????????????5
2.2.1什么是温、湿度控制???????????????????????4 2.2.2温、湿度控制系统的构成?????????????????????5 2.2.3控制对象的特性?????????????????????????5 2.2.4温、湿度控制的种类及其特点???????????????????5 2.3温、湿度传感器的概述?????????????????????????7
2.3.1传感器的概述??????????????????????????7 2.3.2温度传感器的概述????????????????????????8 2.3.3热电偶的概述??????????????????????????9 2.3.4湿度传感器的概述???????????????????????12 2.3.5氯化锂湿敏电阻的概述?????????????????????12
第三章 PLC概述?????????????????????????????14
3.1可编程控制器PLC的概述????????????????????????14
3.1.1可编程控制器PLC的基本概念???????????????????14 3.1.2可编程控制器PLC的发展?????????????????????14 3.1.3可编程控制器PLC的应用?????????????????????15 3.2可编程控制器PLC的特点????????????????????????16 3.3可编程控制器PLC的组成与原理?????????????????????17
3.3.1可编程控制器PLC的组成?????????????????????17
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