【作者】 柯兆盛；

【导师】 郭树旭； 刘宝琦；

【作者基本信息】 吉林大学 ， 电路与系统， 2004， 硕士

【摘要】 温度作为一项热工参数，在工业现场和过程控制中具有至关重要的作用。因而，各种以热电偶、铂电阻作为传感器的温度变送器和数字温度计普遍使用。在这些情况下，多采用有线连接方式采集温度信号及传输数据，这虽然满足了测温目的，但存在电缆布线引起的一些问题。为满足某些测温场合的无线传输温度参数要求，远程控制测温过程，满足测温过程温度信号处理易实现的要求，研制了可无线传输、可视化编程的高精度测温系统。系统中采用无线通讯、温度信号调理和单片计算机电路构成无线传输的高精度数字温度计。采用了单片无线收发芯片nRF401，发射功率为10dBm，传输距离室内可达20m，室外100m。还可根据不同需要安装外接天线，达到更远的距离。采用可视化编程技术构成温度数据接收、处理系统，实现远程控制测温。测温系统从功能可分为三大部分，第一部分由温度传感器铂电阻、温度信号调理电路及中央控制单元组成的温度参数采集和处理电路。铂电阻感受温度信号，送交温度信号调理电路处理。在中央控制单元的控制下，温度信号调理电路将模拟量转化为数字量，经过线性修正，得到最后的测量值并显示给测量者。第二部分，单片无线收/发模块和中央控制单元组成的无线传输部分。主要完成温度数据和测量命令的无线传送和接收。无线收/发模块采用瑞典nordic公司生产的ISM频段的单片无线收/发模块nRF401。中央控制单元控制nRF401功能引脚完成无线传输。使用C语言编制的通信协议，完成错误检验、错误纠正和自动请求重传功能，达到最终的可靠通信。第三部分是可视化编程实现的上位机远程控制部分。此项功能是可选的，控制按键中有一远程控制功能，如果中央控制单元检测到此键按下，其他功能键失效，控制功能全部交由上位机完成。上位机和控制单元通过RS-232口传递数据和控制命令,测温过程控制和数据处理更加方便。温度信号调理电路采用CS5532芯片，调理电桥输出信号，对其实现24bit的A/D转换。CS5532采用∑─△过采样技术，具有转换位数高(24bit)，支持SPI接口协议，便于与MCS51单片计算机连接的特点。CS5532的1脚和2脚连接的是温度参数的模拟输入端，PT100感受温度变化，电桥输出电压发生变化。这个电压直接连接到CS5532的1脚和2脚，在微控制器控制下精确测量出电压值，再依据拟合曲线求出阻值，准确计算温度值。桥臂中的电阻，根据PT100的电流不能超过1mA,计算出其值是1.5k，全部选<WP=49>用高精度电阻，温漂系数满足要求。MAX6138基准电源，输出值是1.205V。3脚和4脚之间连接一个22nF的电容。5脚和6脚分别连接模拟电源的正极（＋2.5V）和负极(-2.5V)，为了保证稳定，使用稳压管LM385。AD7660将＋5V电压转换为－5V电压，为ADC提供负基准电源。9脚和10脚之间连接的是ADC晶振，4.9152MHz。11脚、12脚和13脚三个引脚被称为SPI（串行协议接口），是最简单的串行通信协议，方便与微控器通信。11脚通过隔离器连接到微控制器的21脚做为串行通信的时钟；12脚通过隔离器连接到微控制器的23脚做为串行通信的数据输出端；13脚通过隔离器连接到微控制器的22脚做为串行通信的数据输入端。隔离器的使用减少了干扰，通信更加稳定，提高了通信效率。14脚芯片选择端接地，芯片始终被选中。15脚接＋5V电源。16脚、17脚、19脚、20脚接地。18脚基准输出端，接2.5V基准电压。无线传输高精度测温系统采用nRF401单片无线收/发芯片实现无线传输温度数据和测量命令。nRF401是一个专用工业频段(433MHz)无线收发芯片。它采用FSK(移频键控)调制解调技术，具有无需曼彻斯特编码、误码率低、便于与单片计算机连接等特点。最高传输速率可达20KHz，满足静态温度测量要求。为了可靠通信，编程时可设计通信协议并考虑数据的纠检错。检错可采用效验和方式或更好的CRC(循环冗余校验)校验方式。使用单片计算机的I/O口，分别对nRF401的发送/接收模式、上电/待机模式和通道选择模式进行设置和程序控制，即可实现温度数据的无线发送/接收传输。无线传输高精度测温系统的第三部分，可视化编程实现的上位机远程控制部分。上位机程序主要由可视化编程软件TESTPOINT编写，可以远程完成对温度参数的测量、保存、打印和历史记录的查询。TESTPOINT是美国Capital Equipment Corporation公司生产的一种基于GUI(图形用户界面)的可视化编程软件。TESTPOINT最大的特点是能够很方便实现各种通信，加上其功能强大的数学计算能力，非常适用于各种测量和图形处理软件的编写。通过拖拉TESTPOINT控件和对各种功能的重新组合很方便实现所需要功能,大大缩短了软件开发周期。可视化编程远程控制系统主要具有以下几项功能：(1) 远程测量；(2)数据显示；(3)数据记录；(4)数据保存；(5)数据打印；(6)历史记录查询。 <WP=50>数据通过CODE控件可很方便的与外部程序接口，以便进行保存和处理等操作。使用远程控制程序，可以使测量过程更加直观，便于数据测量、保存、查询等。我们研制的无线传输高精度测温系统由于采用了高精度温度信号调理电路，因此其测量精度主要取决于不同现场测温要求所选用的热电阻。我们铂电阻PT100在实验室条件下对测温系统进行多次无线传?更多还原

【Abstract】 Temperature transducers such as thermocouples and platinum resistances play very important roles in industry scene and process control. Many connection ways of transducers are lineate, and this is not very convenient. So we develop the high precise digital temperature with wireless communication, temperature signal processor and MCU. The system adopts wireless receive and dispatcher single chip nRF401 whose transmitting power is 10dBm and transmission distance is 20m indoors or 100m outdoors. The system is made up of three parts by functions. The first part is composed of platinum resistance temperature transducer, temperature signal adjustment circuit and central controlling unit. The second part is the wireless transmitting part that is composed of wireless receiving and transmitting single chip and central controlling unit. The wireless receiving and transmitting unit is nRF401 that is produced by Nordic corp. from north Europe. The third part is the long-distance controlling unit. This function can be chosen. The controlling unit transmits data and controlling order through RS-232. The circuit adopts CS5532 chip that adjusts the electronic bridge out signal and realizes the A/D transmission in 24 bits. CS5532 adopts super sampling technology and has high transmitting digits (24bits) and supports SPI interface protocol and is easy to connect MCS51 MCU. The 1 pin and 2 pin are simulation temperature input pins. PT100 receives the temperature change and then the output voltage of electronic bridge changes. The voltage connects the 1 pin and 2 pin. The MCU calculates the temperature by the input voltage. A 22 nF capacitance is <WP=52>between the 3 pin and the 4 pin. The 5 pin connects the positive pole (+2.5V) of simulation power supply and the 6 pin connects the negative pole (-2.5V) of simulation power supply. AD7660 transmits +5v voltage to –5v voltage and provides ADC with negative benchmark power supple. The crystal 4.9152MHz is between the 9 pin and the 10 pin. The 11 pin, the 12 pin and the 13 pin are SPL (serial protocol interface) that is the simplest serial communication protocol. The 11 pin connects the 21 pin of MCU by isolation part and its function is the clock of serial communication. The 12 pin connects the 23 pin of MCU by isolation part and its function is the data output pin of serial communication. The 13 pin connects the 22 pin of MCU by isolation part and its function is the data input pin of serial communication. The function of the isolation part is reducing disturbance and making the communication more stabile and improving the communication efficiency. The 14 pin connects the grounding. The 15 pin connects +5v power supple. The 16,17,19,20 pin connect the grounding. The 18 pin connects 2.5v benchmark voltage. The circuit adopts the wireless receiving or transmitting single chip nRF401 whose function is transmitting temperature data and measuring command wirelessly. It adopts FSK modulation/demodulation technology and has low error coding and is easy to connect PC. The highest transmitting velocity is 20kHz. If we want to achieve the wireless receiving or transmitting of temperature data we can use the I/O port of MCU set up and control the receiving/transmitting module of nRF401 and gate choice module.The third part is long-distance controlling part <WP=53>programmed by visual programming TESTPOINT. The Program can measure, save and print the temperature parameter and demand history register. TESTPOINT is a visual programming soft on GUI (graphic user interface) by America Capital Equipment Corporation. TESTPOINT is easy to implement various communications and its math calculation capacity is very good. The visual long-distance controlling programming system has several functions: (1)long-distance measuring; (2)data display; (3)data recording; (4)data saving; (5)data printing; (6)inquiring history recording.It is convenient for data to connect external programming interface by CODE widget. Using long-distance controlling programming can make measuring very eas更多还原