基于PT100的高精度温度采集系统设计与实验研究

The Design and Experimental Study of High Precise Temperature Acquisition System Based on PT100

介绍了温度采集系统的硬件、软件设计和实验研究。系统由下位机和上位机构成,下位机硬件主要由温度传感器PT100、由仪用放大器AD620构成的调理电路、A/D转换器MAX197和微控器AT89S52构成,上位机为PC机。下位机软件用C言语编写,上位机软件用VB6.0设计而成。在恒流源的激励下,PT100的阻值随温度的变化转换成电压的变化,调理电路对电压信号进行放大、变换,输出0V～5V的标准信号,经A/D转换送下位机,再通过串行通信上传给PC机进行存储、显示和图形化。系统采用分段线性化算法,利用MATLAB软件进行最小二乘法线性拟合,得到不同温度区间上的标度变换算法。与WZPB-1型标准铂电阻温度计的对比实验结果表明该系统的测量精度优于±0.1℃,系统工作稳定、可靠。

The design and experimentation of hardware and software of temperature acquisition system based on PT100 are introduced.This system is comprised of the upper computer which is personal computer and the lower computer which is mainly composed of temperature sensor,conditioning circuits made up of instrumentation amplifier AD620,A/D convertor MAX197 and microcontroller AT89S52.The softwares of the upper computer and lower computer are designed based on VB6.0,and the C-language respectively.The change of the PT100’s resistance with temperature is converted to voltage’s variety under excitation of constant current source.Conditioning circuit carries out the magnification and conversion of the voltage signal.The output standard signal from 0V to 5 V is transported to lower computer through A/D converter MAX197.The converted digital data are sent to upper computer through serial communication and are stored in and displayed graphic result on it.The scale conversion algorithm which meets the demand of precision,is gained with the linear least squares during the different temperature section for the relation between resistance and temperature by the aid of MATLAB.The comparative tests with WZPB-1 type standard platinum resistor thermometer show that the measuring accuracy of this system is better than ±0.1 ℃ between 0 ℃ and 100 ℃.The test results also show that this system is credible and stable.