UIT - Secteur de la normalisation des télécommunications ITU - Telecommunication Standardization Sector UIT - Sector de Normalización de las Telecomunicaciones Study Period 1997-2000 Commission d études Study Group Comisión de Estudio 16 Contribution tardive Delayed Contribution Contribución tardía D.xxx Geneva, 7-18 February 2000 Texte disponible seulement en Text available only in Texto disponible solamente en E Question(s): Q.15/SG16 SOURCE*: Nokia Inc. / Nokia Research Center 6000 Connection Drive Irving, Texas 75039 USA Tel : +12147976155 FAX : +19728944589 e-mail : marta.karczewicz@nokia.com TITLE: MVC Decoder Description
標(biāo)簽： Telecommunication Standardization communications normalisation
上傳時(shí)間： 2013-12-24
上傳用戶：541657925
Programming - Verilog VHDL Golden Reference Guide DOULOS Church Hatch, 22 Market Place, Ringwood. Hampshire. BH24 1AW England. Tel (+44) (0)1425 471223 FAX (+44) (0)1425 471573 Email info@doulos.co.uk URL http://www.doulos.co.uk
標(biāo)簽： Programming Reference Ringwood Verilog
上傳時(shí)間： 2017-05-12
上傳用戶：ainimao
匯總了多種設(shè)備的AT指令。包括：PDA，GPRS，FAX等。
上傳時(shí)間： 2017-06-09
上傳用戶：爺?shù)臍赓|(zhì)
The insinuation of telecommunications into the daily fabric of our lives has been arguably the most important and surprising development of the last 25 years. Before this revolution, telephone service and its place in our lives had been largely stable for more than a generation. The growth was, so to speak, lateral, as the global reach of telecommunications extended and more people got telephone service. The distinction between oversea and domestic calls blurred with the advances in switching and transmission, undersea cable, and communication satellites. Traffic on the network remained overwhelmingly voice, largely in analog format with facsimile (FAX) beginning to make inroads.
標(biāo)簽： Telecommunications Modeling Analysis and of
上傳時(shí)間： 2020-05-31
上傳用戶：shancjb
周立功RS485協(xié)議指南，RS485選型及應(yīng)用指南。 1 章 RS-485 選型及應(yīng)用指南 .........................................................................1 1.1 RS-232/422/485 標(biāo)準(zhǔn) ...............................................................................................1 1.1.1 RS-232 標(biāo)準(zhǔn) .....................................................................................................2 1.1.2 RS-422/485 標(biāo)準(zhǔn) ..............................................................................................2 1.2 RS-485/RS-422 芯片................................................................................................5 1.2.1 增強(qiáng)型低功耗半雙工 RS-485 收發(fā)器－SP481E/SP485E ..............................7 1.2.2 1/10 單位負(fù)載 RS-485 收發(fā)器－SP481R/SP485R .....................................10 1.2.3 +3.3V 低功耗半雙工 RS-485 收發(fā)器－SP3481/SP3485..............................13 1.2.4 增強(qiáng)型低功耗全雙工 RS-422 收發(fā)器－SP490E/SP491E ............................15 1.2.5 +3.3V 低功耗全雙工 RS-422 收發(fā)器－SP3490/SP3491..............................20 1.3 RS-485 接口電路 ...................................................................................................22 1.3.1 基本 RS-485 電路...........................................................................................22 1.3.2 隔離 RS-485 電路...........................................................................................23 1.3.3 上電抑制電路.................................................................................................24 1.3.4 RS-485 自動(dòng)換向電路....................................................................................24 1.4 RS-485 通訊協(xié)議 ...................................................................................................25 1.4.1 ModBus 協(xié)議(RTU 模式)...............................................................................25 1.4.2 多功能電能表通訊規(guī)約(DL/T645-1997) ......................................................27 1.5 RS-485 程序設(shè)計(jì) ...................................................................................................28 1.5.1 RS-485 接口電路............................................................................................28 1.5.2 通訊規(guī)約.........................................................................................................28 1.5.3 程序設(shè)計(jì)流程圖.............................................................................................29 1.5.4 數(shù)據(jù)接收部分.................................................................................................29 1.5.5 命令執(zhí)行部分.................................................................................................29 1.5.6 數(shù)據(jù)發(fā)送部分.................................................................................................30 1.5.7 RS-485 程序清單............................................................................................31 1.6 RS-485 應(yīng)用要點(diǎn) ...................................................................................................38 1.6.1 合理選用芯片.................................................................................................38 1.6.2 終端匹配電阻.................................................................................................39 1.6.3 應(yīng)用層通信協(xié)議.............................................................................................39 1.6.4 3V-5V 系統(tǒng)的連接.........................................................................................39 1.6.5 網(wǎng)絡(luò)節(jié)點(diǎn)數(shù).....................................................................................................40 1.6.6 節(jié)點(diǎn)與主干距離.............................................................................................40 1.6.7 RS-485 系統(tǒng)的常見故障及處理方法............................................................40 1.6.8 RS-422 與 RS-485 的網(wǎng)絡(luò)拓樸 .....................................................................41 1.6.9 RS-422 與 RS-485 的接地問題 .....................................................................41 1.6.10 RS-422 與 RS-485 的瞬態(tài)保護(hù) .....................................................................42 1.7 參考文獻(xiàn).................................................................................................................43 廣州周立功單片機(jī)發(fā)展有限公司 Tel：(020)38730977 38730977 FAX：38730925 http://www.zlgmcu.通常的微處理器都集成有 1 路或多路硬件 UART 通道，可以非常方便地實(shí)現(xiàn)串行通訊。 在工業(yè)控制、電力通訊、智能儀表等領(lǐng)域中，也常常使用簡便易用的串行通訊方式作為數(shù)據(jù) 交換的手段。 但是，在工業(yè)控制等環(huán)境中，常會(huì)有電氣噪聲干擾傳輸線路，使用 RS-232 通訊時(shí)經(jīng)常 因外界的電氣干擾而導(dǎo)致信號(hào)傳輸錯(cuò)誤；另外，RS-232 通訊的最大傳輸距離在不增加緩沖 器的情況下只可以達(dá)到 15 米。為了解決上述問題，RS-485/422 通訊方式就應(yīng)運(yùn)而生了。 本章將詳細(xì)介紹 RS-485/422 原理與區(qū)別、元件選擇、參考電路、通訊規(guī)約、程序設(shè)計(jì) 等方面的應(yīng)用要點(diǎn)，以及在產(chǎn)品實(shí)踐中總結(jié)出的一些經(jīng)驗(yàn)、竅門。
上傳時(shí)間： 2022-04-27
上傳用戶：qingfengchizhu
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