PLC温度控制

基于组态软件的S7-200 PLC 温度控制系统

中文摘要

随着自动化水平不断提高，人们对自动化的要求也不断提高。近几年，飞速发展的计算机技术在各行各业得到广泛应用。但是，以之相对应，传统的工业控制软件有开发周期长，重复使用率低，价格高，修改难等缺点。随着越来越多的自动化设备不断得到应用，人们对工业控制软件的要求也不断提高，传统的工业控制软件已无法满足用户的要求。如何方便快捷的使用工业控制软件设计出灵活有效的自动控制系统已成为一个很重要的课题。

本设计以S7-200 PLC 为核心，向上，通过PPI通信和上位机通讯；向下，通过模拟量输入输出模块EM235，对温度对象采样与输出控制。在上位机，使用组态软件MCGS 绘出工艺流程、动画效果等所需的组态界面；通过变量与动画对象的连接，使动画效果与实际变量相对应，这样可以很方便的从组态界面上看到系统实际情况并控制PLC 的各个参数。在温度采样上，使用PT100 热电阻进行采样，使用脉宽调制电路对输出电压进行控制，进而形成完整的温度控制系统。

本文分别通过硬件的选择、设计、使用，软件的选择、编写等方面详细介绍系统各个模块的原理、设计和使用。实验证明，以PLC作为控制器的核心，使用组态软件作为上位机，控制PLC，再通过PLC 编程控制温度对象，这种设计方式方式可以方便快捷灵活的设计出符合要求的控制系统。

关键字：MCGS 组态软件，PPI通讯，PLC ，温度控制系统

S7-200 PLC Temperature Control System Based on

Configuration Software

Abstract

With the continuous development of the industral automatization，it set higher requirements for the automatics．These years, computer technology have been developing rapidly and are widely used in every walk of life．In the other hand，however，the traditional industry controlling software bring with it critical shortcomings such as long development cycle，low reusability,high price and immobility ．As more and more automatic equipments are applied and the requirements for industrial control software are higher and higher，the traditional industry controlling software can't meet customers' demand any more．How to design a flexible and effective automatic control system fastly and conveniently by using industrial control software has become a very important topic．

This thesis focus on S7-200 PLC，which communicating，upward，with upper monitor through PPI ，and also sampling temperature and outputing control single downward through Analog I/O module--EM235．Necessary configuration interface such as software process and animation effects are accomplished by using MCGS configuration software in upper monitor；Through connecting variable to animation effects ，making animation effects the counterpart of actual variable，thus make it convenient to see actual situation and to control each parameter of PLC in configuration interface．In term of temperature sampling，thermal resistor PT100 are used to take sample，PWM are used to control output voltage，so that a complete temperature control system are formed．

This Thesis introduce the principle，design, application of the each system module in detail，which including the type selection，design and application of the hardware，and the selection and writing of the software ．Experiments prove that the design solution which using PLC as control core to control temperature object，configuration software as upper monitor to control PLC，could achieve a desirable control system conveniently, quickly and flexiblely．

Key words: MCGS configuration software, PPI communication, PLC, temperature control system