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兰州交通大学毕业设计(论文)1基于RS-485总线的数据采集系统下位机软硬件设计摘要轮对压力机作为机务检修中的重要组成部分,其在整个检修过程中起着不可忽视的作用。现当今,诸多机务检修期间,多采用简单的人工或半自动压力数据采集,导致精度不高而且进展缓慢。随着电子技术和微型计算机的推广,微机测量和控制技术得到了迅速地发展。单片机因其具有处理能力强、运行速度快、功耗低等优点,从而在数据采集与控制方面得到了广泛的应用。基于这种局面,所以做出对轮对压力的数据采集系统的设计。本文详细阐述了基于RS485总线的数据采集系统下位机软硬件的设计。硬件设计中以AT89C51单片机为控制核心,采用PPM226-LS2-2型压力传感器进行压力的检测,使用ADS7824进行A/D转换,从而实现轮对压力数据的采集;并辅以DS1302实现时间数据的采集,采用MAX485芯片实现TTL电平的转换,从而实现与上位机(即PC机)的串行通信。在本系统的设计中,程序设计采用了C51编程语言,其主要包括数据采集模块,时间提取模块。关键词:数据采集;AT89C51;ADS7824;DS1302;MAX485兰州交通大学毕业设计(论文)2ThesoftwareandhardwaredesignofDataacquisitionsystembasedonRS-485buscomputerABSTRACTAsthemostimportantpartofthelocomotivemaintenance,thewheelpressplaysaninnegligibleaspectinwholeprocessofthemaintenance.Nowdaystheuseofsimpleartificialorsemi-automaticpressuredatacollectionhaveannegativeinfluenceintheaccuracyofmeasurement.Astheelectronictechnologyandmicrocomputerpromotion,computermeasurementandcontroltechnologygetthequickdevelopment.SCMprocessingpowerbecauseofitsstrong,fastandlowpowerconsumptionadvantages,thusinthedataacquisitionandcontrolinawiderangeofapplications.Basedonthiskindofsituation,thedesignofsystemofpressuredateofwheelappears.ThisThesisputeyesonthedesignofthehardwareofdataacquisitionsystembasedonRS485bus.Toachievedateofpressure,Thedesignofhardware,inwhichAT89C51isitscorepart,includenotonlyPPM226-LS2-2toacquisitiondateofpressurebutalsoADS7824totransformbetweenanalogyimformationanddigitalimformation,thissystemuseDS1302toattaindateoftime,anduseMAX485chiptorealizeLevelconversion,Inthissystemthedesignofsoftware,theprogram,whicharerealizedbylanguageofc51,includeDataacquisitionmodulesandTimingextractionmodule.KeyWord:DataAcquisition;AT89C51;ADS7824;DS1302;MAX485兰州交通大学毕业设计(论文)I目录1绪论.................................................................................................................................11.1小型集散测控系统现状.........................................................................................11.2课题研究背景及任务.............................................................................................11.3本设计的主要结构与内容.....................................................................................12数据采集系统下位机总体设计方案.............................................................................32.1设计思路.................................................................................................................32.2系统网络结构框图.................................................................................................33系统硬件电路设计.........................................................................................................53.1AT89C51介绍..........................................................................................................53.1.1AT89CXX系列单片机的内部结构..............................................................53.1.2AT89C51单片机的引脚功能.......................................................................63.1.3中断有关的概念...........................................................................................93.2数据采集模块设计...............................................................................................123.2.1PPM226-LS2-2压力传感器........................................................................123.2.2ADS7824转换电路设计.............................................................................153.2.3时钟芯片DS1302.......................................................................................183.3串口通信电路设计...............................................................................................213.3.1RS232和RS485简介.................................................................................213.3.2与串行口有关的SFR简介........................................................................233.3.3MAX485简介与应用设计..........................................................................263.4其他硬件电路设计...............................................................................................293.4.1单片机存储器的扩展.................................................................................293.4.2复位电路设计.............................................................................................303.4.3时钟电路设计.............................................................................................304系统软件设计...............................................................................................................324.2压力数据采集程序设计.......................................................................................324.3DS1302时钟芯片驱动程序..................................................................................334.4通信程序设计.......................................................................................................36兰州交通大学毕业设计(论文)II总结.................................................................................................................................39致谢.................................................................................................................................40参考文献...............................................................................
本文标题:基于RS-485数据采集系统下位机设计
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