bjmonsoonzh-cnGoodspeed Rss10Mon, 08 Sep 2008 01:26:26 GMT485集线器在总线型数据采集系统的应用Tue, 11 Mar 2008 09:22:12 GMThttp://blog.cechinamag.com/bjmonsoon/70043/message.aspx<p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><b style="mso-bidi-font-weight: normal"><span lang="EN-US" style="FONT-SIZE: 16pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">485</span></b><b style="mso-bidi-font-weight: normal"><span style="FONT-SIZE: 16pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">集线器在总线型数据采集系统的应用分析<span lang="EN-US"><?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p></span></span></b></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 42pt; LINE-HEIGHT: 150%; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-char-indent-count: 3.5" align="left"><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">工业现场使用的智能仪表是随着<span lang="EN-US">80</span>年代初单片机技术的成熟而发展起来的<span lang="EN-US">,</span>现在世界仪表市场基本被智能仪表所垄断。究其原因就是企业信息化的需要<span lang="EN-US">,</span>企业在仪表选型时其中的一个必要条件就是要具有联网通信功能。（<span lang="EN-US">485</span>通讯、以太网通讯、光仟通讯等等）<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 42pt; LINE-HEIGHT: 150%; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-char-indent-count: 3.5" align="left"><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">&nbsp;RS485</span><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">网络：</span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">RS485/MODBUS</span><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">是现在流行的一种布网方式</span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">,</span><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">其特点是实施简单方便</span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">&nbsp;,</span><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">而且现在支持</span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">RS485</span><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">的仪表又特多</span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">,</span><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">特别是在油品行业</span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">RS485/MODBUS</span><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">简直是一统天下</span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">,</span><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">现在的仪表商也纷纷转而支持</span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">RS485/MODBUS,</span><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">原因很简单</span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">,</span><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">象原来的</span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">&nbsp;HART</span><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">仪表想买一个转换口非常困难</span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">&nbsp;</span><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">而且价格昂贵</span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">,RS485</span><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">的转换接口就便宜的多而且种类繁多。至少在低端市场</span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">RS485/MODBUS</span><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">还将是最主要的组网方式</span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">,</span><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">近两三年内不会改变。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 42pt; LINE-HEIGHT: 150%; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-char-indent-count: 3.5" align="left"><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">最初是数据模拟信号输出简单过程量<span lang="EN-US">,</span>后来仪表接口是<span lang="EN-US">RS232</span>接口<span lang="EN-US">,</span>这种接口可以实现点对点的通信方式<span lang="EN-US">,</span>但这种方式不能实现联网功能。随后出现的<span lang="EN-US">RS485</span>解决了这个问题<span lang="EN-US">RS485</span>采用差分信号负逻辑<span lang="EN-US">,</span>＋<span lang="EN-US">2V</span>～＋<span lang="EN-US">6V</span>表示“<?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" /><st1:chmetcnv UnitName="”" SourceValue="0" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on"><span lang="EN-US">0</span>”</st1:chmetcnv><span lang="EN-US">,-&nbsp;6V</span>～<span lang="EN-US">-&nbsp;2V</span>表示“<st1:chmetcnv UnitName="”" SourceValue="1" HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on"><span lang="EN-US">1</span>”</st1:chmetcnv>。<span lang="EN-US">RS485</span>有两线制和四线制两种接线<span lang="EN-US">,</span>四线制只能实现点对点的通信方式<span lang="EN-US">,</span>现很少采用<span lang="EN-US">,</span>现在多采用的是两线制接线方式<span lang="EN-US">,</span>这种接线方式为总线式拓朴结构在同一总线上最多可以挂接<span lang="EN-US">32</span>个结点。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 42pt; LINE-HEIGHT: 150%; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-char-indent-count: 3.5" align="left"><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">在<span lang="EN-US">RS485</span>通信网络中一般采用的是主从通信方式<span lang="EN-US">,</span>即一个主机带多个从机。很多情况下<span lang="EN-US">,</span>连接<span lang="EN-US">RS-485</span>通信链路时只是简单地用一对双绞线将各个接口的“<span lang="EN-US">A</span>”、“<span lang="EN-US">B</span>”端连接起来。而忽略了信号地的连接<span lang="EN-US">,</span>这种连接方法在许多场合是能正常工作的<span lang="EN-US">,</span>但却埋下了很大的隐患<span lang="EN-US">,<o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 42pt; LINE-HEIGHT: 150%; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-char-indent-count: 3.5" align="left"><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">这有二个原因：<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 42pt; LINE-HEIGHT: 150%; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-char-indent-count: 3.5" align="left"><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">(1)</span><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">共模干扰问题：<span lang="EN-US">&nbsp;RS-485</span>接口采用差分方式传输信号方式<span lang="EN-US">,</span>并不需要相对于某个参照点来检测信号<span lang="EN-US">,</span>系统只需检测两线之间的电位差就可以了。但人们往往忽视了收发器有一定的共模电压范围<span lang="EN-US">,RS-485</span>收发器共模电压范围为<span lang="EN-US">-7</span>～<span lang="EN-US">+12V,</span>只有满足上述条件<span lang="EN-US">,</span>整个网络才能正常工作。当网络线路中共模电压超出此范围时就会影响通信的稳定可靠<span lang="EN-US">,</span>甚至损坏接口。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 36pt; LINE-HEIGHT: 150%; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-char-indent-count: 3.0" align="left"><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial"><span style="mso-spacerun: yes">&nbsp;</span>(2)EMI</span><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">问题：发送驱动器输出信号中的共模部分需要一个返回通路<span lang="EN-US">,</span>如没有一个低阻的返回通道（信号地）<span lang="EN-US">,</span>就会以辐射的形式返回源端<span lang="EN-US">,</span>整个总线就会像一个巨大的天线向外辐射电磁波<span lang="EN-US"> <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 36pt; LINE-HEIGHT: 150%; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-char-indent-count: 3.0" align="left"><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">现有的网络拓扑结构一般采用终端匹配<span lang="EN-US">120</span>欧姆电阻的手牵手总线型结构</span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">,</span><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">不支持环形或星形网络。在构建网络时</span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">,</span><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial">请注意如下几点：</span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">&nbsp; </span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial"><o:p></o:p></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 36pt; LINE-HEIGHT: 150%; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-char-indent-count: 3.0" align="left"><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt">（<span lang="EN-US">1</span>）采用一条双绞线电缆作总线<span lang="EN-US">,</span>将各个节点串接起来<span lang="EN-US">,</span>从总线到每个节点的引出线长度应尽量短<span lang="EN-US">,</span>以便使引出线中的反射信号对总线信号的影响最低。有些网络连接尽管不正确<span lang="EN-US">,</span>在短距离、低速率仍可能正常工作<span lang="EN-US">,</span>但随着通信距离的延长或通信速率的提高<span lang="EN-US">,</span>其不良影响会越来越严重<span lang="EN-US">,</span>主要原因是信号在各支路末端反射后与原信号叠加<span lang="EN-US">,</span>会造成信号质量下降。<span lang="EN-US">&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span style="mso-spacerun: yes">&nbsp;&nbsp; </span></span>（<span lang="EN-US">2</span>）应注意总线特性阻抗的连续性<span lang="EN-US">,</span>在阻抗不连续点就会发生信号的反射。如下列几种情况易产生这种不连续性：总线的不同区段采用了不同电缆<span lang="EN-US">,</span>或某一段总线上有过多收发器紧靠在一起安装<span lang="EN-US">,</span>再者是过长的分支线引出到总线。<span lang="EN-US">&nbsp;<o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 42pt; LINE-HEIGHT: 150%; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-char-indent-count: 3.5" align="left"><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体">在工业现场数据采集系统项目中，随着自动化程度的提高和系统组网的需求，项目管理部门要求有主从两个监控中心可以查看，控制整个数据采集终端设备。并且要求在每个监控中心可以通过主机控制采集终端设备对整个工业现场设备进行监控，还要求可以通过服务器将工业现场采集终端设备的数据保存下来。所以就必须要求要多个数据采集设备可以并存于一个控制系统中。</span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: Arial"><o:p></o:p></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 150%; TEXT-ALIGN: left" align="left"><span style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体; mso-bidi-font-family: Arial">　　<span lang="EN-US"><span style="mso-spacerun: yes">&nbsp;&nbsp; </span></span>工程商在施工过程中发现，如果将所有的采集终端设备简单地并联接在一个<span lang="EN-US">485</span>总线上，由于各个主控设备存在电位差及<span lang="EN-US">485</span>总线产生信号反射等原因，导致整个数据采集系统瘫痪从而不能使用，工程商采用深圳市天地华杰科技有限公司的<span lang="EN-US">485</span>总线分割器，将多个主控的设备的<span lang="EN-US">485</span>线连接到<span lang="EN-US">485</span>共享器的输入端口，通过其共享到一个<span lang="EN-US">485</span>输出端口上，由于<span lang="EN-US">485</span>共享器输入端口之间有光电隔离，并且采用独立驱动的方式，从而可以有效的解决电位差及信号反射问题。从而使得多个数据采集终端设备主机共存于一个控制系统中</span><span lang="EN-US" style="FONT-SIZE: 12pt; COLOR: black; LINE-HEIGHT: 150%; FONT-FAMILY: 宋体"><o:p></o:p></span></p>http://blog.cechinamag.com/bjmonsoon/70043/message.aspx解决方案 仪表传感器485转换器（工业级防雷光隔）Tue, 15 Jan 2008 12:17:22 GMThttp://blog.cechinamag.com/bjmonsoon/63857/message.aspxTD-108A是一款工业级的有源防雷光隔型RS-232到RS-485/422的转换器（又称双向光电隔离器，串口转换器，485卡），是深圳市天地华杰科技有限公司为了更有效的解决工业现场中大电磁场下串口设备之间的通信而设计。RS485转换器采用工业级芯片生产，内置工业标准的防雷管和光藕器，在复杂电磁场下有效地保护了串口设备的正常通信。RS485转换器能够将单端的RS-232信号透明地转换为平衡差分的RS-485或RS-422信号，RS485转换器具有自动识别RS-485/RS-422信号的功能，无需人工调拨。同时具有极强的防雷加光电隔离功能。RS485转换器可实现点到点，点到多点的连接。点到多点连接时可连接128个RS-485/RS-422设备。 <table style="WIDTH: 100%; BORDER-TOP-STYLE: double; BORDER-RIGHT-STYLE: double; BORDER-LEFT-STYLE: double; BORDER-BOTTOM-STYLE: double" borderColor="#b0b0b0" cellSpacing="0" cellPadding="0" bgColor="#e9e9e9" border="0" heihgt=""> <tbody> <tr> <td><font size="3"><font face="楷体"_GB2312><strong>&gt;&gt;产品特性：</strong></font></font></td></tr></tbody></table>&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 1.&nbsp;内置高速光藕隔离器，提供3500V的光电隔离电压，快速的瞬态电压抑制器。&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 2.&nbsp;自动发送／接收数据，无需外部的流量控制信号（RTS）&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 3.&nbsp;能够连接128个RS-485或RS-422接口设备　&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 4.&nbsp;电源及双色数据流量指示灯，可检测故障点　&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 5.&nbsp;异步半双工（RS-485）或异步全双工（RS-422）通用，无需跳线设置　&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 6.&nbsp;RS-485／422提供每线光电隔离及600W的防雷保护和防止共地干扰　&nbsp;　&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;7.&nbsp;适用于一切所使用的通讯软件，随插即用　&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;8.&nbsp;支持DOS／WIN95／WIN98／WIN2000／NT／XP　Linux等&nbsp;&nbsp;&nbsp;&nbsp; <br><br> <table style="WIDTH: 100%; BORDER-TOP-STYLE: double; BORDER-RIGHT-STYLE: double; BORDER-LEFT-STYLE: double; BORDER-BOTTOM-STYLE: double" borderColor="#b0b0b0" cellSpacing="0" cellPadding="0" bgColor="#e9e9e9" border="0" heihgt=""> <tbody> <tr> <td><font face="黑体" size="3"><font face="仿宋"_GB2312><strong>&gt;&gt;技术参数:</strong></font>&nbsp;</font></td></tr></tbody></table>&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;接口特性：兼容EIA/TIA的RS-232C/RS-485/RS-422标准。&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;电气接口：RS-232C接口（DB9母头），RS-485/422接口（五位接线端子）。&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;工作方式：异步半双工或异步全双工。&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;传输速率：300—115200BPS&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;◆&nbsp;传输距离：0—5公里&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;◆&nbsp;传输介质：RS-485/422专用屏蔽线。&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;保护等级：600W浪涌保护,15KV静电保护，隔离电压3500V。&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;使用环境：-10℃－50℃，相对湿度5%-95%。&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;尺&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;寸：91mm*66mm*25mm.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;外接电源：电压9v-12v，电流100mA&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br><br> <table style="WIDTH: 100%; BORDER-TOP-STYLE: double; BORDER-RIGHT-STYLE: double; BORDER-LEFT-STYLE: double; BORDER-BOTTOM-STYLE: double" borderColor="#b0b0b0" cellSpacing="0" cellPadding="0" bgColor="#e9e9e9" border="0" heihgt=""> <tbody> <tr> <td><font size="3"><font face="楷体"_GB2312><strong>&gt;&gt;应用领域：</strong></font></font></td></tr></tbody></table>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 工业控制自动化系统，停车场系统，考勤、门禁、售饭，一卡通系统，闭路监控、安防系统、POS系统、楼宇自控系统、自助银行系统，医疗系统。http://blog.cechinamag.com/bjmonsoon/63857/message.aspx产品 工业以太网PLC通讯方法分析Sun, 13 Jan 2008 01:27:08 GMThttp://blog.cechinamag.com/bjmonsoon/63479/message.aspx<div style="PADDING-LEFT: 400px; FILTER: progid:DXImageTransform.Microsoft.Alpha(opacity=100,style=0); PADDING-TOP: 10px; POSITION: absolute" src="http://www.gkong.com/gkong_bbs/face/face1.gif" border="0">&nbsp;<font style="FONT-SIZE: 9pt; LINE-HEIGHT: 15pt"><b>[原创]西门子PLC串口通讯方法分析</b><br>西门子PLC串口通讯方法<br>1、&nbsp;RS485串口通信<br>第三方设备大部分支持，西门子S7&nbsp;PLC可以通过选择自由口通信模式控制串口通信。最简单的情况是只用发送指令（XMT）向打印机或者变频器等第三方设备发送信息。不管任何情况，都必须通过S7&nbsp;PLC编写程序实现。&nbsp;<br>当选择了自由口模式，用户可以通过发送指令（XMT）、接收指令（RCV）、发送中断、接收中断来控制通信口的操作。&nbsp;<br>2、&nbsp;&nbsp;&nbsp;&nbsp;PPI通信&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;PPI协议是S7-200CPU最基本的通信方式，通过原来自身的端口（PORT0或PORT1）就可以实现通信，是S7-200&nbsp;CPU默认的通信方式。&nbsp;<br>PPI是一种主-从协议通信，主-从站在一个令牌环网中。在CPU内用户网络读写指令即可，也就是说网络读写指令是运行在PPI协议上的。因此PPI只在主站侧编写程序就可以了，从站的网络读写指令没有什么意义。&nbsp;<br>3、&nbsp;&nbsp;&nbsp;&nbsp;MPI通信&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;MPI通信是一种比较简单的通信方式，MPI网络通信的速率是19.2Kbit/s~12Mbit/s，MPI网络最多支持连接32个节点，最大通信距离为50M。通信距离远，还可以通过中继器扩展通信距离，但中继器也占用节点。&nbsp;<br>MPI网络节点通常可以挂S7-200、人机介面、编程设备、智能型ET200S及RS485中继器等网络元器件。&nbsp;<br>西门子PLC与PLC之间的MPI通信一般有3种通信方式：&nbsp;<br>&nbsp;&nbsp;&nbsp;1)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;全局数据包通信方式&nbsp;<br>&nbsp;&nbsp;&nbsp;2)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;无组态连接通信方式&nbsp;<br>&nbsp;&nbsp;&nbsp;3)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;组态连接通信方式&nbsp;<br>4、&nbsp;&nbsp;&nbsp;&nbsp;PROFIBUS-DP通信&nbsp;<br>&nbsp;&nbsp;&nbsp;PROFIBUS-DP现场总线是一种开放式现场总线系统，符合欧洲标准和国际标准。PROFIBUS-DP通信的结构非常精简，传输速度很高且稳定，非常适合PLC与现场分散的I/O设备之间的通信。&nbsp;<br>5、&nbsp;&nbsp;&nbsp;&nbsp;以太网通信&nbsp;<br>&nbsp;&nbsp;&nbsp;以太网的核心思想是使用共享的公共传输通道，这个思想早在1968年来源于厦威尔大学。&nbsp;1972年，Metcalfe和David&nbsp;Boggs（两个都是著名网络专家）设置了一套网络，这套网络把不同的ALTO计算机连接在一起，同时还连接了EARS激光打印机。这就是世界上第一个个人计算机局域网，这个网络在1973年5月22日首次运行。Metcalfe在首次运行这天写了一段备忘录，备忘录的意思是把该网络改名为以太网（Ethernet），其灵感来自于“电磁辐射是可以通过发光的以太来传播”这一想法。&nbsp;1979年，DEC、Intel和Xerox共同将网络标准化。&nbsp;<br>1984年，出现了细电缆以太网产品，后来陆续出现了粗电缆、双绞线、CATV同轴电缆、光缆及多种媒体的混合以太网产品。&nbsp;以太网是目前世界上最流行的拓朴标准之一，具有传传播速率高、网络资源丰富、系统功能强、安装简单和使用维护方便等很多优点。<br></font></font>http://blog.cechinamag.com/bjmonsoon/63479/message.aspx解决方案 工业以太网网络传输介质的比较Sun, 09 Dec 2007 09:26:13 GMThttp://blog.cechinamag.com/bjmonsoon/41867/message.aspx<p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">网络上数据的传输需要有<span lang="EN-US">“</span>传输媒体<span lang="EN-US">”</span>，这好比是车辆必须在公路上行驶一样，道路质量的好坏会影响到行车的安全舒适。同样，网络传输媒介的质量好坏也会影响数据传输的质量，包括速率、数据丢失等。<span lang="EN-US"><?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">常用的网络传输媒介可分为两类：一类是有线的；一类是无线的。有线传输媒介主要有同轴电缆、双胶线及光缆；无线媒介有微波、无线电、激光和红外线等。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><b><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">一、同轴电缆（<span lang="EN-US">Coaxial cable</span>）及有关设备</span></b><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体"><o:p></o:p></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">同轴电缆可分为两类：粗缆和细缆，这种电缆在实际应用中很广，比如有线电视网，就是使用同轴电缆。不论是粗缆还是细缆，其中央都是一根铜线，外面包有绝缘层。如图<span lang="EN-US">1</span>所示。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="center"><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体"><?xml:namespace prefix = v ns = "urn:schemas-microsoft-com:vml" /><v:shapetype id=_x0000_t75 stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></v:path><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype><v:shape id=_x0000_i1025 style="WIDTH: 219pt; HEIGHT: 102.75pt" alt="" type="#_x0000_t75"><v:imagedata o:href="http://www.lydffd.com/article1/0277-b-1.jpg" src="file:///C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image001.jpg"></v:imagedata></v:shape><o:p></o:p></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="center"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">图<span lang="EN-US">1<o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">由于同轴电缆绝缘效果佳，频带也宽，数据传输稳定，价格适中，性价比高，是局域网中普遍采用的一种媒介。经常提到的<span lang="EN-US">10BASE-2</span>以太网就是使用细同轴电缆组网的。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">使用同轴电缆组网，需要在两端连接<span lang="EN-US">50</span>欧的反射电阻，这就是通常所说的终端匹配器。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">同轴电缆组网的其它连接设备，细缆与粗缆的不尽相同。即使名称一样，其规格大小也有差别。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">1</span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">、细缆连接设备及技术参数<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">采用细缆组网，除需要电缆外，还需要<span lang="EN-US">BNC</span>头、<span lang="EN-US">T</span>型头及终端匹配器等。如图<span lang="EN-US">2</span>。同轴电缆组网的网卡必须带有细缆连接接口（通常在网卡上标有<span lang="EN-US">"BNC"</span>字样）。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="center"><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体"><v:shape id=_x0000_i1026 style="WIDTH: 274.5pt; HEIGHT: 75pt" alt="" type="#_x0000_t75"><v:imagedata o:href="http://www.lydffd.com/article1/0277-b-2.jpg" src="file:///C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image002.jpg"></v:imagedata></v:shape><o:p></o:p></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">下面是细缆组网的技术参数：<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l1 level1 lfo1; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">最大的干线段长度；<?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" /><st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="False" SourceValue="185" UnitName="米"><span lang="EN-US">185</span>米</st1:chmetcnv><span lang="EN-US"> <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l1 level1 lfo1; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">最大网络干线电缆长度：<st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="False" SourceValue="925" UnitName="米"><span lang="EN-US">925</span>米</st1:chmetcnv><span lang="EN-US"> <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l1 level1 lfo1; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">每条干线段支持的最大结点数：<span lang="EN-US">30 <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l1 level1 lfo1; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">BNC</span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">、<span lang="EN-US">T</span>型连接器之间的最小距离：<st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="False" SourceValue=".5" UnitName="米"><span lang="EN-US">0.5</span>米</st1:chmetcnv><span lang="EN-US"> <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">2</span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">、粗缆连接设备<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">包括转换器、<span lang="EN-US">DIX</span>连接器及电缆、<span lang="EN-US">N</span>－系列插头、<span lang="EN-US">N</span>－系列匹配器，如图<span lang="EN-US">3</span>。使用粗缆组网，网卡必须有<span lang="EN-US">DIX</span>接口（一般标有<span lang="EN-US">DIX</span>字样）。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="center"><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体"><v:shape id=_x0000_i1031 style="WIDTH: 302.25pt; HEIGHT: 95.25pt" alt="" type="#_x0000_t75"><v:imagedata o:href="http://www.lydffd.com/article1/0277-b-3.jpg" src="file:///C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image003.jpg"></v:imagedata></v:shape><o:p></o:p></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">下面是采用粗缆组网的技术参数：<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l2 level1 lfo2; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">最大的干线长度：<st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="False" SourceValue="500" UnitName="米"><span lang="EN-US">500</span>米</st1:chmetcnv><span lang="EN-US"> <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l2 level1 lfo2; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">最大网络干线电缆长度：<st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="False" SourceValue="2500" UnitName="米"><span lang="EN-US">2500</span>米</st1:chmetcnv><span lang="EN-US"> <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l2 level1 lfo2; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">每条干线段支持的最大结点数：<span lang="EN-US">100 <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l2 level1 lfo2; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">收发器之间的最小距离：<st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="False" SourceValue="2.5" UnitName="米"><span lang="EN-US">2.5</span>米</st1:chmetcnv><span lang="EN-US"> <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l2 level1 lfo2; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">收发器电缆的最大长度：<st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="False" SourceValue="50" UnitName="米"><span lang="EN-US">50</span>米</st1:chmetcnv><span lang="EN-US">&nbsp; <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><b><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">二、双绞线（<span lang="EN-US">Twisted-pair</span>）</span></b><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体"><o:p></o:p></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">双绞线是由两条导线按一定扭距相互绞合在一起的类似于电话线的传输媒体，每根线加绝缘层并有颜色来标记，如图<span lang="EN-US">4</span>所示。成对线的扭绞旨在使电磁辐射和外部电磁干扰减到最小。双绞线按其电气特性分级或分类。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="center"><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体"><v:shape id=_x0000_i1027 style="WIDTH: 170.25pt; HEIGHT: 103.5pt" alt="" type="#_x0000_t75"><v:imagedata o:href="http://www.lydffd.com/article1/0277-b-4.jpg" src="file:///C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image004.jpg"></v:imagedata></v:shape><o:p></o:p></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="center"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">图<span lang="EN-US">4<o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan" align="left"><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">EIA/TIA</span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">（电气工业协会<span lang="EN-US">/</span>电信工业协会）第一类双绞线通常在<span lang="EN-US">LAN</span>技术中不使用<span lang="EN-US">,</span>主要用于模拟话音。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan" align="left"><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">EIA/TIA</span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">第二类可用于综合业务数据网（数据），如数字话音、<span lang="EN-US">IBM3270</span>等。这两类双绞线在<span lang="EN-US">LAN</span>中很少使用。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan" align="left"><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">EIA/TIA</span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">第三类双绞线是一种<span lang="EN-US">24WG</span>的四对非屏蔽双绞线<span lang="EN-US">,</span>符合<span lang="EN-US">EIA/TIA568</span>标准中确定的<span lang="EN-US">100</span>欧姆水平步线电缆的要求，可用来进行<span lang="EN-US">10Mbps</span>和<span lang="EN-US">IEEE802.3 10Base-T</span>的话音和数据传输。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan" align="left"><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">EIA/TIA</span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">第四类双绞线在性能上比第三类有一定改进<span lang="EN-US">,</span>适用于包括<span lang="EN-US">16Mbps</span>令牌环局域网在内的数据传输速率。其传输特性满足<span lang="EN-US">EIA/TIA Technical Services Bulletin </span>定义的第四类电缆的规范，也满足<span lang="EN-US">NEMA</span>和<span lang="EN-US">UL</span>　<span lang="EN-US">Twisted-pair Qualification Program</span>定义的规范。这类双绞线可以是<span lang="EN-US">UTP</span>，也可以是<span lang="EN-US">STP</span>。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan" align="left"><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">EIA/TIA</span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">第五类双绞线是<span lang="EN-US">24AWG</span>的<span lang="EN-US">4</span>对电缆，比<span lang="EN-US">100</span>欧姆低损耗电缆具有更好的传输特性，并适用于<span lang="EN-US">16Mbps</span>以上的速率，最高可达<span lang="EN-US">100Mbps</span>。<span lang="EN-US">150</span>欧姆<span lang="EN-US">STP</span>是另外一种高性能屏蔽式<span lang="EN-US">22AWG</span>或<span lang="EN-US">24AWG</span>的电缆，它支持的数据传输速率可达<span lang="EN-US">100Mbps</span>或更高，并支持<span lang="EN-US">600MHz</span>频带上的全息图象。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">使用双绞线组网，网卡必须带有<span lang="EN-US">RJ45</span>接口，另外还需要一个非常重要的设备<span lang="EN-US">----</span>集线器<span lang="EN-US">HUB</span>。图<span lang="EN-US">5</span>是<span lang="EN-US">RJ45</span>接头示意图。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="center"><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体"><v:shape id=_x0000_i1028 style="WIDTH: 146.25pt; HEIGHT: 75pt" alt="" type="#_x0000_t75"><v:imagedata o:href="http://www.lydffd.com/article1/0277-b-5.jpg" src="file:///C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image005.jpg"></v:imagedata></v:shape><o:p></o:p></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="center"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">图<span lang="EN-US">5<o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">根据<span lang="EN-US">AT&amp;T</span>接线标准，双绞线与<span lang="EN-US">RJ45</span>接头的连接方法在<span lang="EN-US">10BASE-T</span>和<span lang="EN-US">100BASE-T</span>是相同的。它需要<span lang="EN-US">4</span>根导线通信，两条用于发送数据，两条用于接收数据，如图<span lang="EN-US">6</span>。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="center"><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体"><v:shape id=_x0000_i1029 style="WIDTH: 56.25pt; HEIGHT: 139.5pt" alt="" type="#_x0000_t75"><v:imagedata o:href="http://www.lydffd.com/article1/0277-b-6.jpg" src="file:///C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image006.jpg"></v:imagedata></v:shape><o:p></o:p></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="center"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">图<span lang="EN-US">6<o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">注意，在接线时，一定要按线的颜色对应接线，否则会使通信不稳定。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">双绞线（<span lang="EN-US">10BASE-T</span>）以太网技术规范可归结为<st1:chsdate w:st="on" IsROCDate="False" IsLunarDate="False" Day="3" Month="4" Year="2005"><span lang="EN-US">5-4-3</span></st1:chsdate><span lang="EN-US">-2-1</span>规则：<span lang="EN-US"> <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l3 level1 lfo3; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">允许<span lang="EN-US">5</span>个网段，每网段最大长度<st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="False" SourceValue="100" UnitName="米"><span lang="EN-US">100</span>米</st1:chmetcnv><span lang="EN-US"> <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l3 level1 lfo3; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">在同一信道上允许连接<span lang="EN-US">4</span>个中继器或集线器<span lang="EN-US"> <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l3 level1 lfo3; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">在其中的三个网段上可以增加节点<span lang="EN-US"> <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l3 level1 lfo3; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">在另外两个网段上，除做中继器链路外，不能接任何节点<span lang="EN-US"> <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l3 level1 lfo3; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">上述将组建一个大型的冲突域，最大站点数<span lang="EN-US">1024</span>，网络直径达<st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="False" SourceValue="2500" UnitName="米"><span lang="EN-US">2500</span>米</st1:chmetcnv><span lang="EN-US"> <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">上述规则只是一个粗略的设计指南，实际的数据因厂家不同而异，现在的集线器一般可以级链<span lang="EN-US">7</span>层。双绞线组网的基本要求是网络部件间延时满足如下公式：<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="center"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">（中继器延时<span lang="EN-US"> + </span>电缆延时<span lang="EN-US"> + </span>网卡延时<span lang="EN-US">×2</span>）<span lang="EN-US">×2 &lt; 51.2ms<o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">利用双绞线组网，可以获得良好的稳定性，在实际应用中越来越多。尤其是近年来，快速以太网的发展，利用双绞线组建不须再增加其它设备，因此被业界人士看好。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><b><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">三、光纤（<span lang="EN-US">Fiber Optical Cable</span>）</span></b><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体"><o:p></o:p></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">组建快速网络，光纤是最好的选择。光缆是由许多细如发丝的塑胶或玻璃纤维外加绝缘护套组成，光束在玻璃纤维内传输，防磁防电，传输稳定，质量高，适于高速网络和骨干网。如图<span lang="EN-US">7</span>所示。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="center"><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体"><v:shape id=_x0000_i1030 style="WIDTH: 191.25pt; HEIGHT: 88.5pt" alt="" type="#_x0000_t75"><v:imagedata o:href="http://www.lydffd.com/article1/0277-b-7.jpg" src="file:///C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image007.jpg"></v:imagedata></v:shape><o:p></o:p></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="center"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">图<span lang="EN-US">7<o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">利用光缆连接网络，每端必须连接光<span lang="EN-US">/</span>电转换器，另外还需要一些其它辅助设备。基于光缆的网络，国际标准化组织<span lang="EN-US">ISO</span>制定了许多规范，具体如下：<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l5 level1 lfo4; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">10BASE-FL <o:p></o:p></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l5 level1 lfo4; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">10BASE-FB <o:p></o:p></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l5 level1 lfo4; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">10BASE-FP <o:p></o:p></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">其中<span lang="EN-US">10BASE-FL</span>是使用最广泛的数据格式，下面是其组网规则：<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l0 level1 lfo5; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">最大段长：<span lang="EN-US"> <st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="False" SourceValue="2000" UnitName="m">2000M</st1:chmetcnv> <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l0 level1 lfo5; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">每段最大节点（<span lang="EN-US">NODE</span>）数：<span lang="EN-US">2 <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l0 level1 lfo5; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">每网络最大节点（<span lang="EN-US">NODE</span>）数：<span lang="EN-US"> 1024 <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l0 level1 lfo5; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">每链的最大<span lang="EN-US">HUB</span>数：<span lang="EN-US">4 <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">表<span lang="EN-US">1</span>是三种传输媒介的比较。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="center"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">表<span lang="EN-US">1 </span>同轴电缆、双绞线、光缆的性能比较<span lang="EN-US"><o:p></o:p></span></span></p> <div align="center"> <table class="MsoNormalTable" style="BORDER-RIGHT: medium none; BORDER-TOP: medium none; BORDER-LEFT: medium none; WIDTH: 80%; BORDER-BOTTOM: medium none; BORDER-COLLAPSE: collapse; mso-border-alt: outset black .75pt; mso-padding-alt: 2.25pt 2.25pt 2.25pt 2.25pt" cellSpacing="0" cellPadding="0" width="80%" border="1"> <tbody> <tr style="mso-yfti-irow: 0; mso-yfti-firstrow: yes"> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: black 1pt inset; PADDING-LEFT: 2.25pt; BACKGROUND: silver; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: black 1pt inset; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; mso-border-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">传输媒介<span lang="EN-US"><o:p></o:p></span></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: black 1pt inset; PADDING-LEFT: 2.25pt; BACKGROUND: silver; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">价格<span lang="EN-US"><o:p></o:p></span></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: black 1pt inset; PADDING-LEFT: 2.25pt; BACKGROUND: silver; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">电磁干扰<span lang="EN-US"><o:p></o:p></span></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: black 1pt inset; PADDING-LEFT: 2.25pt; BACKGROUND: silver; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">频带宽度<span lang="EN-US"><o:p></o:p></span></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: black 1pt inset; PADDING-LEFT: 2.25pt; BACKGROUND: silver; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">单段最大长度<span lang="EN-US"><o:p></o:p></span></span></p></td></tr> <tr style="mso-yfti-irow: 1"> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: black 1pt inset; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span lang="EN-US" style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">UTP<o:p></o:p></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">最便宜<span lang="EN-US"><o:p></o:p></span></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">高<span lang="EN-US"><o:p></o:p></span></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">低<span lang="EN-US"><o:p></o:p></span></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="True" SourceValue="100" UnitName="米"><span lang="EN-US" style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">100 </span><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">米</span></st1:chmetcnv><span lang="EN-US" style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体"><o:p></o:p></span></p></td></tr> <tr style="mso-yfti-irow: 2"> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: black 1pt inset; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span lang="EN-US" style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">STP<o:p></o:p></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">一般<span lang="EN-US"><o:p></o:p></span></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">低<span lang="EN-US"><o:p></o:p></span></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">中 等<span lang="EN-US"><o:p></o:p></span></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="True" SourceValue="100" UnitName="米"><span lang="EN-US" style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">100 </span><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">米</span></st1:chmetcnv><span lang="EN-US" style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体"><o:p></o:p></span></p></td></tr> <tr style="mso-yfti-irow: 3"> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: black 1pt inset; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">同轴电缆<span lang="EN-US"><o:p></o:p></span></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">一般<span lang="EN-US"><o:p></o:p></span></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">低<span lang="EN-US"><o:p></o:p></span></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">高<span lang="EN-US"><o:p></o:p></span></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="False" SourceValue="185" UnitName="米"><span lang="EN-US" style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">185</span><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">米</span></st1:chmetcnv><span lang="EN-US" style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">/<st1:chmetcnv w:st="on" TCSC="0" NumberType="1" Negative="False" HasSpace="False" SourceValue="500" UnitName="米">500<span lang="EN-US"><span lang="EN-US">米</span></span></st1:chmetcnv><o:p></o:p></span></p></td></tr> <tr style="mso-yfti-irow: 4; mso-yfti-lastrow: yes"> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: black 1pt inset; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">光缆<span lang="EN-US"><o:p></o:p></span></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">最高<span lang="EN-US"><o:p></o:p></span></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">没有<span lang="EN-US"><o:p></o:p></span></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">极高<span lang="EN-US"><o:p></o:p></span></span></p></td> <td style="BORDER-RIGHT: black 1pt inset; PADDING-RIGHT: 2.25pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 2.25pt; PADDING-BOTTOM: 2.25pt; BORDER-LEFT: #ece9d8; WIDTH: 20%; PADDING-TOP: 2.25pt; BORDER-BOTTOM: black 1pt inset; BACKGROUND-COLOR: transparent; mso-border-alt: inset black .75pt; mso-border-left-alt: inset black .75pt; mso-border-top-alt: inset black .75pt" width="20%"> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align="center"><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">几十公里<span lang="EN-US"><o:p></o:p></span></span></p></td></tr></tbody></table></div> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align="left"><b><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">四、无线媒体</span></b><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体"><o:p></o:p></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">上述三种传输媒体的有一个共同的缺点，那便是都需要一根线缆连接电脑，这在很多场合下是不方便的。无线媒体不使用电子或光学导体。大多数情况下地球的大气便是数据的物理性通路。从理论上讲，无线媒体最好应用于难以布线的场合或远程通信。无线媒体有三种主要类型：无线电、微波及红外线。下面我们主要介绍无线电传输介质。<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan" align="left"><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">无线电的频率范围在<span lang="EN-US">10KHz-16KHz</span>之间。在电磁频谱里，属于<span lang="EN-US">“</span>对频<span lang="EN-US">”</span>。使用无线电的时候，需要考虑的一个重要问题是电磁波频率的范围（频谱）是相当有限的。其中大部分都已被电视、广播以及重要的政府和军队系统占用。因此，只有很少一部分留给网络电脑使用，而且这些频率也大部分都由国内<span lang="EN-US">“</span>无线电管理委员会（无委会）<span lang="EN-US">”</span>统一管制。要使用一个受管制的频率必须向无委会申请许可证，这在一定程度上会相当不便。如果设备使用的是未经管制的频率，则功率必须在<span lang="EN-US">1W</span>以下，这种管制目的是限制设备的作用范围，从而限制对其它信号的干扰。用网络术语来说，这相当于限制了未管制无线电的通信带宽。下面这些频率是未受管制的：<span lang="EN-US"><o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l4 level1 lfo6; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">902 </span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">～<span lang="EN-US"> 925MHz <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l4 level1 lfo6; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">2.4GHz(</span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">全球通用<span lang="EN-US">) <o:p></o:p></span></span></p> <p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt 36pt; TEXT-INDENT: 18pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l4 level1 lfo6; tab-stops: list 36.0pt" align="left"><span lang="EN-US" style="FONT-SIZE: 10pt; FONT-FAMILY: Symbol; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: Symbol; mso-font-kerning: 0pt; mso-bidi-font-family: Symbol"><span style="mso-list: Ignore">·<span style="FONT: 7pt 'Times New Roman'">&nbsp;&nbsp; </span></span></span><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">5.72 </span><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">～<span lang="EN-US"> 5.85 GHz <o:p></o:p></span></span></p><span style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">无线电波可以穿透墙壁，也可以到达普通网络线缆无法到达的地方。针对无线电链路连接的网络，现在已有相当坚实的工业基础，在业界也得到迅速发展。</span>http://blog.cechinamag.com/bjmonsoon/41867/message.aspx产品 工业以太网485总线分割器Thu, 22 Nov 2007 09:45:11 GMThttp://blog.cechinamag.com/bjmonsoon/38525/message.aspxTD-1204是一款RS-485集线器（又称RS-485总线分割集中器，RS-485HUB）。是深圳市天地华杰科技有限公司为了解决复杂电磁场环境下RS-485总线大系统中星型布线而专业设计。该RS485集线器采用双向透明传输，RS485集线器它能够把一路RS-485或一路RS-232总线分割为4路RS-485总线，或者把四路RS-485信号汇集到一路RS-485或一路RS-232总线上来。并且每个端口都独立具有光隔、短路、开路保护功能。在系统发生故障的时候，内置的控制器能够及时的切断有故障的端口。使RS485集线器保证每一端口都起到独立工作，达到互不干扰的效果。每个端口可同时连接32个接点，可延长1200米RS-485信号。是改变RS-485总线布线中单一结构的最好选择。<font face="黑体" size="3"><strong> <table style="WIDTH: 100%; BORDER-TOP-STYLE: double; BORDER-RIGHT-STYLE: double; BORDER-LEFT-STYLE: double; BORDER-BOTTOM-STYLE: double" borderColor="#b0b0b0" cellSpacing="0" cellPadding="0" bgColor="#e9e9e9" border="0" heihgt=""> <tbody> <tr> <td><font face="仿宋"_GB2312 size="3"><strong>&gt;&gt;产品特性：</strong></font></td></tr></tbody></table></strong></font><font face="宋体">&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 1. 输入端提供RS-232和RS-485两个接口，输出端提供四个RS-485接口&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 2. 通信速率300～115200bps自适应，免除了手动设置波特率的麻烦&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 3. 每路RS-485接口带防雷防浪涌功能，每路RS-485接口之间相互隔离，互不干扰。&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 4. 电源为外部供电方式，提供同心插座和双端子接线柱两种供电方法。&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 5. 多个TD-1204可以五级级联，最大扩展256路RS-485总线。&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 6. 每路接口可接32个标准RS-485设备（节点）&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 7. 具备零延时自动收发转换功能&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 8. 独有的电路自动检测功能&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 9. 支持热拔插功能、即插即用&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 10. 能够适应用户的任何应用软件&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 11，可当做四个RS-232到RS-485转换器来使用<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp; 12. 自适应通信速率功能&nbsp;&nbsp;&nbsp; <br><br></font><font face="黑体" size="3"><strong> <table style="WIDTH: 100%; BORDER-TOP-STYLE: double; BORDER-RIGHT-STYLE: double; BORDER-LEFT-STYLE: double; BORDER-BOTTOM-STYLE: double" borderColor="#b0b0b0" cellSpacing="0" cellPadding="0" bgColor="#e9e9e9" border="0" heihgt=""> <tbody> <tr> <td><font face="仿宋"_GB2312 size="3"><strong>&gt;&gt;技术参数：</strong></font></td></tr></tbody></table></strong></font><font face="宋体">&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 接口标准：兼容EIA/TIA的RS-232C和RS-485标准&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 通信速率：300～115200bps自适应&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 通信距离：每个通信口可以使您的网络延伸1200m&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 数据流控：功能复用口（COM）的RS232口无须RTS/CTS硬件流控，为自动流控&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 接口特征：&nbsp;4路独立的RS-485信号输出，每路接口之间彼此独立&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 连接设备：&nbsp;多机通信32、64、128个节点&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 电气接口:&nbsp;&nbsp;RS-232（DB9母头），RS&nbsp;485（接线端子）&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 传输介质：&nbsp;超五类双绞屏蔽线或者RS-485专用线&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 工作方式：&nbsp;异步工作,点对点或多点,2线半双工&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 隔&nbsp;离&nbsp;度：&nbsp;隔离电压3500V&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 传输距离：&nbsp;RS-485端1200米,RS-232端建议不超过5米&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 尺&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;寸：&nbsp;&nbsp;140L*130W*30H毫米&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 使用环境：&nbsp;温度：-20℃－60℃，湿度：5％—95％&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br><br></font><font face="黑体" size="3"><strong> <table style="WIDTH: 100%; BORDER-TOP-STYLE: double; BORDER-RIGHT-STYLE: double; BORDER-LEFT-STYLE: double; BORDER-BOTTOM-STYLE: double" borderColor="#b0b0b0" cellSpacing="0" cellPadding="0" bgColor="#e9e9e9" border="0" heihgt=""> <tbody> <tr> <td><font face="仿宋"_GB2312 size="3"><strong>&gt;&gt;应用领域：</strong></font></td></tr></tbody></table></strong></font><font face="宋体">&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 工业控制自动化、道路交通控制自动化、智能卡、考勤、门禁、售饭系统、工业集散分布系统、闭路监控、安防系统、POS系统、楼宇自控系统、自助银行系统&nbsp;。电信通讯系统、银行、保险系统、&nbsp;远程分散式设备控制、智能自动报警及消防联动系统、楼宇自动控制系统、大型零售系统、网络家电等。</font>http://blog.cechinamag.com/bjmonsoon/38525/message.aspx产品 工业电器485网络信号放大器Thu, 22 Nov 2007 09:43:57 GMThttp://blog.cechinamag.com/bjmonsoon/38524/message.aspxTD-109是一款RS-485/422中继器（又称RS-485/422信号放大器，RS-485/422信号延长器，485增强器），是深圳市天地华杰科技有限公司为了解决RS-485/422信号在传输中衰弱的问题而专业设计。该RS485中继器是采用工业级设计，可以使RS-485/422信号延伸4000英尺（1200米）或再增加32个连接点，同时具有很强的防雷和光电隔离保护功能，能为两端的RS-485/422设备提供有效的保护。RS485中继器它支持RS-485总线与RS-422总线的自动切换，无需人工调拨。是增强RS-485/422信号的最好选择！&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br><br> <table style="WIDTH: 100%; BORDER-TOP-STYLE: double; BORDER-RIGHT-STYLE: double; BORDER-LEFT-STYLE: double; BORDER-BOTTOM-STYLE: double" borderColor="#b0b0b0" cellSpacing="0" cellPadding="0" bgColor="#e9e9e9" border="0" heihgt=""> <tbody> <tr> <td><font face="仿宋"_GB2312 size="3"><strong>&gt;&gt;产品特性：</strong></font></td></tr></tbody></table>&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 1.&nbsp;&nbsp;产品安装方便、可选择壁挂式或导轨安装&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 2.&nbsp;&nbsp;接线采用五位接线端子，方便布线&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 3.&nbsp;&nbsp;高效的防雷管可以有效地抑制闪电(Lightning)和ESD，&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 4.&nbsp;&nbsp;提供每线600W的雷击浪涌保护功率&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp; 5.&nbsp;&nbsp;增加RS-422/RS-485总线网络中485设备的数目.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 6.&nbsp;&nbsp;能够提供3500V的隔离电压，可以有效的防止雷击和共地干扰。&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 7.&nbsp;&nbsp;采用数据流向控制技术，自动判数据传输方向，零延时设计，自动侦测串口信号速率&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 8.&nbsp;&nbsp;能够有效地延长RS-422/RS-485信号1200米。&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 9.&nbsp;&nbsp;全金属外壳，防静电，抗干扰能力强。&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br> <table style="WIDTH: 100%; BORDER-TOP-STYLE: double; BORDER-RIGHT-STYLE: double; BORDER-LEFT-STYLE: double; BORDER-BOTTOM-STYLE: double" borderColor="#b0b0b0" cellSpacing="0" cellPadding="0" bgColor="#e9e9e9" border="0" heihgt=""> <tbody> <tr> <td><font face="仿宋"_GB2312 size="3"><strong>&gt;&gt;技术参数：</strong></font>&nbsp;&nbsp;</td></tr></tbody></table>&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;接口特性：串口符合EIARS-232/485/422协议&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;电气接口：接口（五位接线端子）&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;传输介质：超五类双绞屏蔽线或者485专用线&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;传输距离：每增加一个中继器，可使您的485网络再延长1200m&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;通信速率：300---115200bps&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;挂接点数：32个标准节点&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;隔离电压：2500V连续&nbsp;7000V脉冲&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;保护等级：600W浪涌保护,15KV静电保护&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;工作方式：异步工作,点对点或多点,2线半双工,4线全双工&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;隔&nbsp;离&nbsp;&nbsp;度：隔离电压3000V&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;传输距离：RS-485/RS-422端1200米&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;尺&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;寸：95L*65W*25H（毫米&nbsp;）&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆&nbsp;使用环境：温度：-20℃－60℃，湿度：5％—95％&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br><br> <table style="WIDTH: 100%; BORDER-TOP-STYLE: double; BORDER-RIGHT-STYLE: double; BORDER-LEFT-STYLE: double; BORDER-BOTTOM-STYLE: double" borderColor="#b0b0b0" cellSpacing="0" cellPadding="0" bgColor="#e9e9e9" border="0" heihgt=""> <tbody> <tr> <td><font face="仿宋"_GB2312 size="3"><strong>&gt;&gt;应用领域：</strong></font>&nbsp;</td></tr></tbody></table>&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 用于点对点、点对多点通讯、工业控制自动化、道路交通控制自动化、智能卡、考勤、门禁、售饭系统、工业集散分布系统、闭路监控、安防系统、POS系统、楼宇自控系统、自助银行系统&nbsp;。电信通讯系统、银行、保险系统、&nbsp;远程分散式设备控制、智能自动报警及消防联动系统、楼宇自动控制系统、大型零售系统、网络家电等。http://blog.cechinamag.com/bjmonsoon/38524/message.aspx产品 工业以太网RS232转485防雷光隔转换器Thu, 22 Nov 2007 09:43:03 GMThttp://blog.cechinamag.com/bjmonsoon/38523/message.aspxTD-108是一款有源防雷光隔型RS-232到RS-485/422的转换器（又称RS-485/422光电隔离器、光隔型串口转换器，RS485转换器），是深圳市天地华杰科技有限公司为了更好解决和保护RS-232串口设备与RS-485/422串口设备之间的数据通信而专业设计。该RS485转换器能够将单端的RS-232信号透明的转换为平衡差分的RS-485或RS-422信号，同时具有自动识别RS-485/RS-422信号的功能，无需人工调拨。RS485转换器同时采用两种隔离手段：一种是防雷管和光藕隔离，第二种是电路隔离，双管其下，极强地起到了防雷和光电隔离功能。RS485转换器连接可实现点到点，点到多点的连接。点到多点连接时可连接128个RS-485/RS-422设备。RS485转换器是户外扩展系统的最好选择！<font face="黑体" size="3"><strong> <p> <table style="WIDTH: 100%; BORDER-TOP-STYLE: double; BORDER-RIGHT-STYLE: double; BORDER-LEFT-STYLE: double; BORDER-BOTTOM-STYLE: double" borderColor="#b0b0b0" cellSpacing="0" cellPadding="0" align="left" bgColor="#e9e9e9" border="0" heihgt=""> <tbody> <tr> <td><font face="楷体"_GB2312 size="3"><strong>&gt;&gt;产品特性：</strong></font></td></tr></tbody></table></p> <p></strong></font><font face="宋体">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </font></p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 1.&nbsp;内置高速光藕隔离器，提供3500V的光电隔离电压，快速的瞬态电压抑制器。&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 2. 自动发送／接收数据，无需外部的流量控制信号（RTS）&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 3. 能够连接128个RS-485或RS-422接口设备　&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 4. 电源及双色数据流量指示灯，可检测故障点　&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 5. 异步半双工（RS-485）或异步全双工（RS-422）通用，无需跳线设置　&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 6. RS-485／422提供每线光电隔离及600W的防雷保护和防止共地干扰　&nbsp;　&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 7. 适用于一切所使用的通讯软件，随插即用　&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 8. 支持DOS／WIN95／WIN98／WIN2000／NT／XP　Linux等&nbsp;&nbsp;&nbsp;</p> <p><font face="黑体" size="3"><strong> <table style="WIDTH: 100%; BORDER-TOP-STYLE: double; BORDER-RIGHT-STYLE: double; BORDER-LEFT-STYLE: double; BORDER-BOTTOM-STYLE: double" borderColor="#b0b0b0" cellSpacing="0" cellPadding="0" bgColor="#e9e9e9" border="0" heihgt=""> <tbody> <tr> <td><font face="楷体"_GB2312 size="3"><strong>&gt;&gt;技术参数&nbsp;:</strong></font>&nbsp;</td></tr></tbody></table></strong></font><font face="宋体">&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 接口特性：兼容EIA/TIA的RS-232C/RS-485/RS-422标准。&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 电气接口：RS-232C接口（DB9母型），RS-485/422接口（五位接线端子）。&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 工作方式：异步半双工或异步全双工。&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 传输速率：300—115200BPS&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 传输距离：0—5公里&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 传输介质：RS-485/422专用屏蔽线。&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 保护等级：600W浪涌保护,15KV静电保护，隔离电压3500V。&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 使用环境：-10℃－50℃，相对湿度5%-95%。&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 尺&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; &nbsp;寸：91mm*66mm*25mm.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ◆ 外接电源：电压9v-12v，电流100mA&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </font></p> <p><font face="黑体" size="3"><strong> <table style="WIDTH: 100%; BORDER-TOP-STYLE: double; BORDER-RIGHT-STYLE: double; BORDER-LEFT-STYLE: double; BORDER-BOTTOM-STYLE: double" borderColor="#b0b0b0" cellSpacing="0" cellPadding="0" bgColor="#e9e9e9" border="0" heihgt=""> <tbody> <tr> <td><font face="楷体"_GB2312 size="3"><strong>&gt;&gt;应用领域：</strong></font></td></tr></tbody></table></strong></font><font face="宋体">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 工业控制自动化系统，停车场系统，考勤、门禁、售饭，一卡通系统，闭路监控、安防系统、POS系统、楼宇自控系统、自助银行系统，医疗系统。</font></p>http://blog.cechinamag.com/bjmonsoon/38523/message.aspx产品 仪表传感器全面解析RS232 RS422 RS485的本质区别（2）Thu, 22 Nov 2007 09:10:38 GMThttp://blog.cechinamag.com/bjmonsoon/38502/message.aspx<p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><span class="tpc"><span style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: 宋体; mso-hansi-font-family: Arial; mso-bidi-font-family: Arial; mso-ascii-font-family: Arial">三、</span></span><span class="tpc"><span lang="EN-US" style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: Arial">RS-422</span></span><span class="tpc"><span style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: 宋体; mso-hansi-font-family: Arial; mso-bidi-font-family: Arial; mso-ascii-font-family: Arial">与</span></span><span class="tpc"><span lang="EN-US" style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: Arial">RS-485</span></span><span class="tpc"><span style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: 宋体; mso-hansi-font-family: Arial; mso-bidi-font-family: Arial; mso-ascii-font-family: Arial">串行接口标准</span></span><span class="tpc"><span style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: Arial"> </span></span><span lang="EN-US" style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: Arial"><br></span><span class="tpc"><span style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: 宋体; mso-hansi-font-family: Arial; mso-bidi-font-family: Arial; mso-ascii-font-family: Arial">　　</span></span><span class="tpc"><span lang="EN-US" style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: Arial">1</span></span><span class="tpc"><span style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: 宋体; mso-hansi-font-family: Arial; mso-bidi-font-family: Arial; mso-ascii-font-family: Arial">．平衡传输</span></span><span class="tpc"><span style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: Arial"> </span></span><span lang="EN-US" style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: Arial"><br></span><span class="tpc"><span style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: 宋体; mso-hansi-font-family: Arial; mso-bidi-font-family: Arial; mso-ascii-font-family: Arial">　　</span></span><span class="tpc"><span lang="EN-US" style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: Arial">RS-422</span></span><span class="tpc"><span style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: 宋体; mso-hansi-font-family: Arial; mso-bidi-font-family: Arial; mso-ascii-font-family: Arial">、</span></span><span class="tpc"><span lang="EN-US" style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: Arial">RS-485</span></span><span class="tpc"><span style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: 宋体; mso-hansi-font-family: Arial; mso-bidi-font-family: Arial; mso-ascii-font-family: Arial">与</span></span><span class="tpc"><span lang="EN-US" style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: Arial">RS-232</span></span><span class="tpc"><span style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: 宋体; mso-hansi-font-family: Arial; mso-bidi-font-family: Arial; mso-ascii-font-family: Arial">不一样，数据信号采用差分传输方式，也称作平衡传输，它使用一对双绞线，将其中一线定义为</span></span><span class="tpc"><span lang="EN-US" style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: Arial">A</span></span><span class="tpc"><span style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: 宋体; mso-hansi-font-family: Arial; mso-bidi-font-family: Arial; mso-ascii-font-family: Arial">，另一线定义为</span></span><span class="tpc"><span lang="EN-US" style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: Arial">B</span></span><span class="tpc"><span style="FONT-SIZE: 10pt; COLOR: #666666; FONT-FAMILY: 宋体; mso-hansi-font-family: Arial; mso-bidi-font-fam