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编号：毕业设计说明书题目：基于RS485总线的远程温度监测系统题目类型：理论研究实验研究√工程设计工程技术研究软件开发2010年6月10日第I页共Ⅱ页摘要控制领域中的分布式监控系统具有节点多、传输距离远以及现场工作条件恶劣等特点，因此需要一种能够支持多节点、远距离通信以及传输信号安全可靠的总线构成网络。本文给出的一种基于RS485总线的远程监测实时温度的方法，具体介绍了RS485总线的通信原理、串行通信原理、监控系统的组成和功能电路模块，并且着重介绍了RS485总线的特点和通信协议的设计，电路连接和通信软件的设计方法。在此基础上设计了一套完整的远程温度监控系统，每个从机都能实时对环境周围的温度采集，并且将所采集到的数据发送给主机；而主机可以对接收到的每个从机所发送的信息进行相应的处理，并且向所需要控制的从机发送相应的命令。本系统应用STC89C52单片机完成数据的采集、处理、对所采集到的温度进行处理和对数据的传输进行处理，通过矩阵键盘输入命令，并用LCD12864液晶屏显示实时状态、设定信息和所采集到的温度。RS485串口通信实现了主机对从机的监控和控制。通过硬件和软件的联合调试证明，系统能实现实时温度采集，并对温度超出范围时进行了处理，由于使用的是DS18B20数字温度传感器进行温度采集，使所采集到的温度的精确度也比较好。该监测系统具有体积小，价格便宜、实用性好和方便携带等优点，可以在生活小区、工厂、楼宇等领域使用。关键词：单片机；数字温度传感器DS18B20；液晶显示；RS485总线；串行通信第II页共Ⅱ页AbstractControlthefieldofdistributedcontrolsystemwithmultiplenodes,transmissiondistanceandon-siteworkingconditionsandothercharacteristics，Therefore,itneedsabuswhichwithmulti-nodesupport,remotecommunications,andsignaltransmissionofsafeandreliabletoformnetwork.ThispaperpresentedamethodwhichbasedonRS485bustoremotemonitoringofthereal-timetemperature,detaileddescriptionoftheRS485buscommunicationtheory,serialcommunicationtheory,controlsystemcomponentsandfunctionsofcircuitmodule.,andemphaticallyintroducedthecharacteristicsoftheRS485busandthedesignofcommunicationprotocols,circuitconnectionandcommunicationsoftwaredesign.Onthisbasisdesignedacompletesetofremotetemperaturemonitoringsystem,eachslavecanreal-timecapturethetemperaturewhicharoundoftheenvironmental,andthedatacollectedwillbesenttothehost;Thehostcandockeachreceivedinformationsentfromthemachineandmaketheappropriatetreatment,andsendstheappropriatecommandtoltheslaveofneedcontrol.MCUtocompletethesystemapplicationSTC89C52datacollection,processing,thetemperatureofthecollecteddataforprocessingandtransmissionofprocessed,inputscommandsthroughthematrixkey-board,andusesLCD12864displayreal-timestatus,thesetinformationandthetemperatureofcollected.RS485SerialCommunicationachievedthehostmachinemonitoringandcontrolingtheslave.Throughthethejointcommissioningofhardwareandsoftwareproved,Systemcancollectreal-timetemperature,anddealwithwhenthetemperaturegoesoutofscope,duetousetheDS18B20digitaltemperaturesensortocollectthetemperature,sothattheaccuracyoftemperatureofthecollectedisbetter.Themonitoringsystemissmall,cheap,practical,goodandeasytocarry,etc.,soitcanbeuseinthelivingarea,factories,buildingsandotherareas.Keywords:MCU;DigitalTemperatureSensorsDS18B20;LCDdisplay;RS485bus;SerialCommunication第I页共Ⅱ页目录引言...........................................................................................................................................11系统设计..........................................................................................................................21.1任务要求.............................................................................................................................21.2总体设计.............................................................................................................................22设计方案论证.................................................................................................................32.1主机部分方案论证.............................................................................................................32.2从机部分方案论证.............................................................................................................32.3通讯总线接口方案论证.....................................................................................................33系统硬件电路设计.......................................................................................................53.1主控机电路设计.................................................................................................................53.1.1单片机STC89C52外围电路设计...................................................................................53.1.2液晶显示电路设计.........................................................................................................73.1.3报警电路设计.................................................................................................................93.1.4键盘控制电路设计.......................................................................................................103.2从机电路设计..................................................................................................................113.2.1温度采集电路设计.......................................................................................................113.3主从机RS485接口电路设计..........................................................................................143.4程序下载电路设计..........................................................................................................154RS485通信技术基本原理........................................................................................174.1RS485多机通信概述.......................................................................................................174.2多机通信基本原理..........................................................................................................174.3串行通信原理...................................