文档介绍：锅炉温度控制
摘要
随着微电子技术及计算机技术的发展,可编程序控制器的运算功能、接口功能越来越强。A/D及D/A技术引入PLC系统后,使PLC不再局限于逻辑控制范围。本课题是利用西门子系列PLC模拟量模块EM235对温度模拟量信号进行采集和处理,通过S7-200的PID指令和模拟量模块一起使用实现对锅炉水温的调节,采用了LabVIEW实现PC与PLC的实时监控功能。
下位机控制系统,是利用PLC作为系统的主控制器,由加热电阻丝加热,温度反馈信号经A/D转换后,送入PLC中进行处理,在PLC中将测量元件测得的锅炉水温与设定值进行比较,并采用PID进行调节。
上位机监控软件采用图形化语言LabVIEW,设计人机界面,并实现上位机与下位机之间的通信,实现对控制对象信号和设备的集中管理与监控,可显示温度测量值、给定值、输出值以及PID参数值,实现对锅炉系统温度的监控。在这一部分,本文详细介绍了利用LabVIEW中的VISA模块设计串口通信的方法。
以PLC为下位机,以LabVIEW为上位机开发平台,利用LabVIEW软件强大的数据运算能力和分析能力,并通过LabVIEW与PLC之间串口通信,组成实时监控的图形显示平台。调试结果表明,该系统具有界面友好、运行可靠、易于操作等特点。
关键词:PLC,LabVIEW,温度控制,PID,串口通信
ABSTRACT
With microelectronics puter technology development, the programmable controller operational function, interface function stronger. A/D and D/A technology introduced PLC system, make no longer confined to PLC control logic. This topic is using the Siemens PLC analogue series EM235 module for temperature analog signal acquisition and processing, by S7-200 PID instructions and analog module of boiler water use of LabVIEW, adopts the PC and PLC real-time monitoring function.
The use of PLC control system, is the main controller, A system of heating and heat resistance wire, temperature feedback signals via A/D conversion, into the process of PLC, measuring element in PLC will of boiler water temperature, pared with the data using PID adjusted.
PC monitor software using graphical LabVIEW, man-machine interface design language, and realize the PC and the realization of munication between the object of control signals, and the centralized management and monitoring device can display temperature measurement values and a given value, the output value and PID parameters of boiler, the temperature control system. In this part, this paper introduces the design of LabVIEW VISA module method of munication.
For the machine with PLC for PC LabVIEW, using LabVIEW software development platform, strong ability of data analysis putation ability, and through munication with PLC LabVIEW, real-time monitor