智能温度变送器设计.docVIP

PAGE PAGE I 内蒙古科技大学 本科生毕业设计说明书（毕业论文） 题 目：智能温度变送器设计 学生姓名：郭龙文 学 号：0705112338 专 业：测控技术与仪器 班 级：测控07-3班 指导教师：李文涛 教授 内蒙古科技大学毕业设计说明书（毕业论文） 智能温度变送器设计 摘 要 温度变送器作为一种现场设备被广泛应用在工业过程控制系统中。随着自动化技术的发展，对温度变送器有了更高的要求。传统的模拟式温度变送器所具有的固有缺点已不能满足控制系统的要求。 本论文主要阐述了智能温度变送器的发展现状，针对热电偶和热电阻的输出特性，设计了一种基于单片机的智能温度变送器。该智能温度变送器以STC89C52单片机为核心，针对温度传感器输出的信号不同，设计了由集成仪表放大器AD623和数控电位器X9241组成的增益放大环节，可以根据传感器的类型，由程序来控制放大器的放大倍数。将传感器的输出信号放大到0~5V，接入A/D转换器PCF8591T，使得采集的模拟信号转换为数字信号，再由单片机进行数字滤波、线性化以及标度变换等数据处理后，通过LCD进行显示，并经D/A转换器PCF8591T及V/I转换器转换为4~20mA DC信号输出。 设计主要围绕硬件设计和软件编程来进行。Proteus仿真及调试结果表明，该智能温度变送器使用方便，性能稳定，达到了预期的设计目标。 关键词：热电偶；热电阻；变送器；单片机 内蒙古科技大学毕业设计说明书（毕业论文） Design of Intelligent Temperature Transmitter Abstract Temperature transmitter is widely used in control system of industrial process as one kind of field instrument. Because traditional analog temperature transmitter can no longer meet the new demand owing to its inherent shortcoming, the development of automation technology requires higher demand for temperature transmitters. This thesis analyzes general development of intelligent temperature transmitter and designs intelligent temperature transmitter which is based on SCM according the thermocouple and RTD. The core of temperature transmitter is STC89C52 based on SCM. According to the output signal range of the sensor, the system sets the gain of amplification link which is composed of AD623 and X9241 by way of program. As the temperature transmitter amplifies the weak signal to DC 0～5V, access A/D converter PCF8591T, digital converter will change the analog signals into digital signals. Digital signals output as 4 ~ 20mA DC, by the single-chip digital filtering, linearization, scaling transform data processing, carried through the LCD display, the D/A converter PCF8591T and V/I converter. The main work includes hardware designing and software compiling. The Proteus simulation test and truly showing result tests that the system has advantages such as friendly interface, conve