【作者】 陈祥；

【导师】 曾明如；

【作者基本信息】 南昌大学 ， 控制理论与控制工程， 2006， 硕士

【摘要】 现场总线作为过程自动化、制造自动化等领域现场智能设备之间的互连通信网络，建立了生产过程现场控制设备之间以及与更高控制管理层网络之间的联系。而HART总线技术成功地将数字信号通信叠加到现有的现场控制系统上，对改进智能仪表间的通信提供了无风险的解决方案。因此，研究和开发符合HART协议的智能仪表具有十分重要的现实意义。 随着微型计算机技术和嵌入式系统的迅速发展和广泛应用，它的高速和灵活性日益为人们所认识，将微处理器运用于参数的实时检测和分析已经成为一种发展趋势。它为仪器仪表实现产品的微型化、数字化、智能化和网络化提供了有利的条件，同时也使得仪器仪表在性能上向高精确度、高可靠性、高环境适应性方向发展。 本文结合广东新会康宇测控仪器仪表工程有限公司变送器部的新产品开发项目，研究开发了一种基于HART协议的智能压力变送器，该电路使用微处理芯片XE88LCO5A为核心建立电路连接。利用XE88LCO5A芯片的低功耗特性以及片内丰富的外设模块，用纯硬件的方法解决了HART总线设备的低功耗这一技术难关，完全符合HART通信协议技术规范要求。 为了同时解决压力传感器输出特性的非线性和温度漂移问题，能在传感器工作范围内得到一个一致的被测压力计算公式，本文中提出以传感器输入值和温度为变量，利用二元多项式重构传感器输出压力信号，再利用最小二乘法进行曲面拟合法获得补偿系数，将其写入系统的EEPROM中，使得系统在获得传感器输出信号和温度之后能简便地计算出被测压力值，较好地做到了非线性校正与温度补偿。本方法在传感器静态特性标定数据范围内得到了便于工程计算的一致表达式，同时解决了传感器的非线性和温度漂移两个主要问题，计算所用数据量大大小于插值法，并且在提高智能变送器精度方面也取得了很好的效果。 该智能变送器可与多种压力传感器连接，具有很强的通用性。相对于国外的同类产品具有较高的性价比。更多还原

【Abstract】 Field bus, make relationships between the process control devices and even the high control management network, as a communication network among intelligent instruments in the field of process control automation, manufacturing automation. As HART field bus proposals a solution superimposing the digital signal at the present field control system without risk, the intelligent instruments based on HART field bus technique are widely used.With the development and appliance of the microcomputer and the embedded system, its high speed and agility are recognized by people. It is a trend to use microprocessor for a real-time supervisory control and data analysis. It has unexampled predominance in realizing the micromation, digital communication, intelligentize and network network connections of the instrumental production. The same time, it makes the instrumental production developmentting towards high accuracy, high reliability, high adaptability.In this paper ,the research and development of a intelligent pressure transmitter based on HART protocol is introduced , which is a project of guangdong xinhui instrument company.The intelligent pressure transmitter is built around a XE88LC05 microcontroller. The design of hardware and software as well as the implementation of HART digital communication are described concretely. The difficult problem in the design of intelligent transmitter, low power consumption technology is also presented.To overcome the output nonlinearity and temperature drift of pressure sensor, the method to reconstruct the sensor output with the input pressure and sensor temperature using bivariate polynomial is proposed. The coefficients of curved surface formulation are decided by the least square method and saved by EEPROM. Then the system can compute the input pressure depend on the curved surface formulation when the sensor output and temperature are knowable. The method it not only benefits temperature compensation but also helps non-linear rectifying.The advantage of the method proposed here is that it provides a way to get a consistent expression at the range of sensor calibration data, which eliminates the effect of output nonlinearity and temperature drift of the sensor and demands least data stored than the interpolation, and the accuracy of sensor can be reached to 0.2%.The intelligent pressure transmitter is universal for it can be used in many kind of sensor. Compare with overseas manufacture, it has more performance than cost.更多还原