Modbus协议规范(中文).rar_modbus协议

<html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta charset="utf-8"> <meta name="generator" content="pdf2htmlEX"> <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"> <link rel="stylesheet" href="https://static.pudn.com/base/css/base.min.css"> <link rel="stylesheet" href="https://static.pudn.com/base/css/fancy.min.css"> <link rel="stylesheet" href="https://static.pudn.com/prod/directory_preview_static/625232cb74bc5c0105bd3a96/raw.css"> <script src="https://static.pudn.com/base/js/compatibility.min.js"></script> <script src="https://static.pudn.com/base/js/pdf2htmlEX.min.js"></script> <script> try{ pdf2htmlEX.defaultViewer = new pdf2htmlEX.Viewer({}); }catch(e){} </script> <title></title> </head> <body> <div id="sidebar" style="display: none"> <div id="outline"> </div> </div> <div id="pf1" class="pf w0 h0" data-page-no="1"><div class="pc pc1 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/625232cb74bc5c0105bd3a96/bg1.jpg"><div class="t m0 x1 h2 y1 ff1 fs0 fc0 sc0 ls0 ws0">GB/T<span class="_ _0"> </span><span class="ff2">××××—××××</span></div><div class="c x2 y2 w2 h3"><div class="t m0 x3 h4 y3 ff1 fs0 fc0 sc1 ls0 ws0">0</div></div><div class="t m0 x1 h5 y4 ff2 fs1 fc0 sc1 ls0 ws0">前<span class="_ _1"> </span>言</div><div class="t m0 x4 h6 y5 ff1 fs2 fc0 sc0 ls0 ws0">-----------</div><div class="t m0 x5 h7 y6 ff2 fs2 fc0 sc0 ls0 ws0">串行链路和</div><div class="t m0 x6 h6 y5 ff1 fs2 fc0 sc0 ls0 ws0">TCP/<span class="_ _2"></span>IP</div><div class="t m0 x7 h7 y6 ff2 fs2 fc0 sc0 ls0 ws0">上的</div><div class="t m0 x8 h6 y5 ff1 fs2 fc0 sc0 ls0 ws0">MODBUS</div><div class="t m0 x9 h7 y6 ff2 fs2 fc0 sc0 ls0 ws0">标准介绍</div><div class="t m0 xa h7 y7 ff2 fs2 fc0 sc1 ls0 ws0">该标准包括两个通信规程中使用的</div><div class="t m0 xb h6 y8 ff1 fs2 fc0 sc1 ls0 ws0">MODBUS</div><div class="t m0 xc h7 y7 ff2 fs2 fc0 sc1 ls0 ws0">应用层协议和服务规范：</div><div class="t m0 xa h7 y9 ff2 fs2 fc0 sc1 ls0 ws0">·串行链路上的</div><div class="t m0 xd h6 ya ff1 fs2 fc0 sc1 ls0 ws0">MODBUS</div><div class="t m0 xe h6 yb ff1 fs2 fc0 sc1 ls0 ws0">MODBUS</div><div class="t m0 xf h7 yc ff2 fs2 fc0 sc1 ls0 ws0">串行链路取决于</div><div class="t m0 x10 h6 yb ff1 fs2 fc0 sc1 ls0 ws0">TIA/EIA</div><div class="t m0 x7 h7 yc ff2 fs2 fc0 sc1 ls0 ws0">标准：</div><div class="t m0 x11 h6 yb ff1 fs2 fc0 sc1 ls0 ws0">232-F</div><div class="t m0 x12 h7 yc ff2 fs2 fc0 sc1 ls0 ws0">和</div><div class="t m0 x13 h6 yb ff1 fs2 fc0 sc1 ls0 ws0">485-A</div><div class="t m0 x14 h7 yc ff2 fs2 fc0 sc1 ls0 ws0">。</div><div class="t m0 xa h7 yd ff2 fs2 fc0 sc1 ls0 ws0">·</div><div class="t m0 x15 h6 ye ff1 fs2 fc0 sc1 ls0 ws0">TCP/IP</div><div class="t m0 x16 h7 yd ff2 fs2 fc0 sc1 ls0 ws0">上的</div><div class="t m0 xf h6 ye ff1 fs2 fc0 sc1 ls0 ws0">MODBUS</div><div class="t m0 xe h6 yf ff1 fs2 fc0 sc1 ls0 ws0">MODBUS<span class="_"> </span>TCP/I<span class="_ _3"></span>P</div><div class="t m0 x17 h7 y10 ff2 fs2 fc0 sc1 ls0 ws0">取决于</div><div class="t m0 x18 h6 yf ff1 fs2 fc0 sc1 ls0 ws0">IETF</div><div class="t m0 x19 h7 y10 ff2 fs2 fc0 sc1 ls0 ws0">标准：</div><div class="t m0 x1a h6 yf ff1 fs2 fc0 sc1 ls0 ws0">RFC793</div><div class="t m0 x1b h7 y10 ff2 fs2 fc0 sc1 ls0 ws0">和</div><div class="t m0 x12 h6 yf ff1 fs2 fc0 sc1 ls0 ws0">RFC791</div><div class="t m0 x1c h7 y10 ff2 fs2 fc0 sc1 ls0 ws0">有关。</div><div class="t m0 xa h7 y11 ff2 fs2 fc0 sc1 ls0 ws0">串行<span class="_ _2"></span>链<span class="_ _2"></span>路和</div><div class="t m0 x1d h6 y12 ff1 fs2 fc0 sc1 ls0 ws0">TCP/IP</div><div class="t m0 x1e h7 y11 ff2 fs2 fc0 sc1 ls0 ws0">上的</div><div class="t m0 x1f h6 y12 ff1 fs2 fc0 sc1 ls0 ws0">MODBUS</div><div class="t m0 x19 h7 y11 ff2 fs2 fc0 sc1 ls0 ws0">是根<span class="_ _2"></span>据<span class="_ _2"></span>相应</div><div class="t m0 x20 h6 y12 ff1 fs2 fc0 sc1 ls0 ws0">ISO</div><div class="t m0 x21 h7 y11 ff2 fs2 fc0 sc1 ls0 ws0">层模<span class="_ _2"></span>型<span class="_ _2"></span>说明<span class="_ _2"></span>的<span class="_ _2"></span>两<span class="_ _2"></span>个<span class="_ _2"></span>通信<span class="_ _2"></span>规<span class="_ _2"></span>程<span class="_ _2"></span>。</div><div class="t m0 x1 h7 y13 ff2 fs2 fc0 sc1 ls0 ws0">下图强调指出了该标准的主要部分。<span class="_ _4"></span>绿色方框表示规范。<span class="_ _4"></span>灰色方框表示已有的国际标准</div><div class="t m0 x1 h7 y14 ff2 fs2 fc0 sc1 ls0 ws0">（</div><div class="t m0 x22 h6 y15 ff1 fs2 fc0 sc1 ls0 ws0">TIA/EIA</div><div class="t m0 x23 h7 y14 ff2 fs2 fc0 sc1 ls0 ws0">和</div><div class="t m0 x24 h6 y15 ff1 fs2 fc0 sc1 ls0 ws0">IETF</div><div class="t m0 x25 h7 y14 ff2 fs2 fc0 sc1 ls0 ws0">标准）<span class="_ _5"></span>。</div><div class="c x26 y16 w3 h8"><div class="t m1 x27 h9 y17 ff1 fs3 fc0 sc1 ls0 ws0"> </div></div><div class="c x28 y18 w4 ha"><div class="t m1 x0 hb y19 ff1 fs4 fc0 sc1 ls0 ws0">MODBU<span class="_ _3"></span>S<span class="_"> </span><span class="ff2">报文</span></div><div class="t m1 x0 hb y1a ff2 fs4 fc0 sc1 ls0 ws0">传输在<span class="_ _6"> </span><span class="ff1">T<span class="_ _2"></span>CP/IP</span></div><div class="t m1 x0 hb y1b ff2 fs4 fc0 sc1 ls0 ws0">上的实现指南<span class="ff1"> </span></div><div class="t m1 x0 hb y1c ff1 fs4 fc0 sc1 ls0 ws0">49<span class="_"> </span><span class="ff2">页</span><span class="fs3"> </span></div></div><div class="c x29 y1d w5 hc"><div class="t m1 x0 hb y1e ff1 fs4 fc0 sc1 ls0 ws0">MODB<span class="_ _2"></span>US<span class="_ _7"> </span><span class="ff2">报<span class="_ _8"> </span>文</span></div><div class="t m1 x0 hb y1f ff2 fs4 fc0 sc1 ls0 ws0">传<span class="_ _9"></span>输<span class="_ _9"></span>在<span class="_ _9"></span>串<span class="_ _9"></span>行<span class="_ _9"></span>链<span class="_ _a"></span>路</div><div class="t m1 x0 hb y20 ff2 fs4 fc0 sc1 ls0 ws0">上的实现指南<span class="ff1"> </span></div><div class="t m1 x0 hb y21 ff1 fs4 fc0 sc1 ls0 ws0">45<span class="_"> </span><span class="ff2">页</span><span class="fs3"> </span></div></div><div class="c x2a y22 w6 hd"><div class="t m1 x2b hb y23 ff1 fs4 fc0 sc1 ls0 ws0">MODBU<span class="_ _3"></span>S<span class="_"> </span><span class="ff2">应用层</span><span class="fs3"> </span></div></div><div class="c x2c y24 w7 hd"><div class="t m1 x0 hb y25 ff2 fs3 fc0 sc1 ls0 ws0">在<span class="_ _b"> </span><span class="ff1">TCP/IP<span class="_"> </span></span>上的<span class="_ _b"> </span><span class="ff1 fs4">MODBU<span class="_ _3"></span>S<span class="_"> </span><span class="ff2">映射</span><span class="fs3"> </span></span></div></div><div class="c x2c y26 w8 he"><div class="t m1 x0 h9 y27 ff1 fs3 fc0 sc1 ls0 ws0">TCP </div><div class="t m1 x0 h9 y28 ff1 fs3 fc0 sc1 ls0 ws0">IET<span class="_ _2"></span>F RFC<span class="_ _3"></span> 79<span class="_ _3"></span>3 </div></div><div class="c x2c y29 w9 he"><div class="t m1 x0 h9 y2a ff1 fs3 fc0 sc1 ls0 ws0">IP </div><div class="t m1 x0 h9 y2b ff1 fs3 fc0 sc1 ls0 ws0">IET<span class="_ _2"></span>F RFC<span class="_ _3"></span> 79<span class="_ _3"></span>1 </div></div><div class="c x2d y2c wa he"><div class="t m1 x0 hf y2d ff2 fs3 fc0 sc1 ls0 ws0">串行链路主站<span class="ff1">/</span>从站<span class="ff1"> </span></div></div><div class="c x2c y2c w9 he"><div class="t m1 x0 hf y2e ff2 fs3 fc0 sc1 ls0 ws0">以太网<span class="_ _b"> </span><span class="ff1">II/802<span class="_ _3"></span>.3 </span></div><div class="t m1 x0 h9 y2f ff1 fs3 fc0 sc1 ls0 ws0">IEE<span class="_ _2"></span>E 802<span class="_ _3"></span>.2<span class="_ _3"></span> </div></div><div class="c x2d y30 wb hd"><div class="t m1 x0 h9 y31 ff1 fs3 fc0 sc1 ls0 ws0">TIA/EIA-<span class="_ _3"></span>23<span class="_ _3"></span>2-<span class="_ _3"></span>F </div></div><div class="c x2e y30 wb hd"><div class="t m1 x0 h9 y31 ff1 fs3 fc0 sc1 ls0 ws0">TIA/EIA-<span class="_ _3"></span>48<span class="_ _3"></span>5-<span class="_ _3"></span>A<span class="_ _3"></span> </div></div><div class="c x2f y30 wc hd"><div class="t m1 x0 hf y31 ff2 fs3 fc0 sc1 ls0 ws0">以太网物理层<span class="ff1"> </span></div></div><div class="c x30 y32 wd h10"><div class="t m1 x0 h9 y33 ff1 fs3 fc0 sc1 ls0 ws0">Modbus</div><div class="t m1 x0 hf y34 ff2 fs3 fc0 sc1 ls0 ws0">协<span class="_ _a"></span>议<span class="_ _a"></span>规<span class="_ _a"></span>范</div><div class="t m1 x0 hf y35 ff1 fs3 fc0 sc1 ls0 ws0">45<span class="_ _c"> </span><span class="ff2">页</span> </div></div><div class="c x0 y36 we h0"><div class="t m0 xa h6 y37 ff1 fs2 fc0 sc1 ls0 ws0">MODBUS</div><div class="t m0 x31 h7 y38 ff2 fs2 fc0 sc1 ls0 ws0">标准分为三部分。第一部分（<span class="_ _5"></span>“</div><div class="t m0 x32 h6 y37 ff1 fs2 fc0 sc1 ls0 ws0">Modbus</div><div class="t m0 x33 h7 y38 ff2 fs2 fc0 sc1 ls0 ws0">协议规范”<span class="_ _5"></span>）描述了</div><div class="t m0 x34 h6 y37 ff1 fs2 fc0 sc1 ls0 ws0">MODBUS</div><div class="t m0 x35 h7 y38 ff2 fs2 fc0 sc1 ls0 ws0">事</div><div class="t m0 x1 h7 y39 ff2 fs2 fc0 sc1 ls0 ws0">物处理。<span class="_ _d"></span>第二部分<span class="_ _d"></span>（<span class="_ _5"></span>“</div><div class="t m0 x36 h6 y3a ff1 fs2 fc0 sc1 ls0 ws0">MODBUS</div><div class="t m0 x37 h7 y39 ff2 fs2 fc0 sc1 ls0 ws0">报文传输在</div><div class="t m0 x38 h6 y3a ff1 fs2 fc0 sc1 ls0 ws0">TCP/IP</div><div class="t m0 x39 h7 y39 ff2 fs2 fc0 sc1 ls0 ws0">上的实现指南”<span class="_ _5"></span>）<span class="_ _d"></span>提供了一个有助于</div><div class="t m0 x1 h7 y3b ff2 fs2 fc0 sc1 ls0 ws0">开发<span class="_ _2"></span>者<span class="_ _2"></span>实<span class="_ _2"></span>现</div><div class="t m0 x3a h6 y3c ff1 fs2 fc0 sc1 ls0 ws0">TCP/IP</div><div class="t m0 x3b h7 y3b ff2 fs2 fc0 sc1 ls0 ws0">上的</div><div class="t m0 x3c h6 y3c ff1 fs2 fc0 sc1 ls0 ws0">MODBUS</div><div class="t m0 x3d h7 y3b ff2 fs2 fc0 sc1 ls0 ws0">应用<span class="_ _2"></span>层<span class="_ _2"></span>的<span class="_ _2"></span>参<span class="_ _2"></span>考<span class="_ _2"></span>信<span class="_ _2"></span>息<span class="_ _2"></span>。<span class="_ _2"></span>第<span class="_ _2"></span>三<span class="_ _2"></span>部<span class="_ _2"></span>分（<span class="_ _e"></span>“</div><div class="t m0 x3e h6 y3c ff1 fs2 fc0 sc1 ls0 ws0">MODBUS</div><div class="t m0 x3f h7 y3b ff2 fs2 fc0 sc1 ls0 ws0">报文<span class="_ _2"></span>传</div><div class="t m0 x1 h7 y3d ff2 fs2 fc0 sc1 ls0 ws0">输在<span class="_ _9"></span>串行<span class="_ _2"></span>链<span class="_ _9"></span>路上<span class="_ _2"></span>的<span class="_ _2"></span>实<span class="_ _2"></span>现<span class="_ _2"></span>指<span class="_ _9"></span>南”<span class="_ _e"></span>）提<span class="_ _9"></span>供了<span class="_ _2"></span>一<span class="_ _9"></span>个有<span class="_ _2"></span>助<span class="_ _2"></span>于<span class="_ _2"></span>开<span class="_ _2"></span>发<span class="_ _9"></span>者实<span class="_ _2"></span>现<span class="_ _2"></span>串<span class="_ _2"></span>行<span class="_ _2"></span>链<span class="_ _9"></span>路上<span class="_ _2"></span>的</div><div class="t m0 x40 h6 y3e ff1 fs2 fc0 sc1 ls0 ws0">MODBUS</div><div class="t m0 x1 h7 y3f ff2 fs2 fc0 sc1 ls0 ws0">应用层的参考信息。</div></div></div><div class="pi" data-data='{"ctm":[1.611830,0.000000,0.000000,1.611830,0.000000,0.000000]}'></div></div> </body> </html>

<div id="pf3" class="pf w0 h0" data-page-no="3"><div class="pc pc3 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/625232cb74bc5c0105bd3a96/bg3.jpg"><div class="t m0 x1 h2 y1 ff1 fs0 fc0 sc0 ls0 ws0">GB/T<span class="_ _0"> </span><span class="ff2">××××—××××</span></div><div class="c x2 y2 w2 h3"><div class="t m0 x3 h4 y3 ff1 fs0 fc0 sc1 ls0 ws0">2</div></div><div class="t m0 x43 h12 y41 ff2 fs6 fc0 sc0 ls0 ws0">第一<span class="_ _2"></span>部分：<span class="_ _2"></span><span class="ff1">Mod<span class="_ _2"></span>bus<span class="_"> </span></span>协议</div><div class="t m0 x44 h5 y42 ff1 fs1 fc0 sc0 ls0 ws0">1<span class="_ _10"> </span><span class="ff2">引言</span></div><div class="t m0 x1 h5 y43 ff2 fs1 fc0 sc0 ls0 ws0">1.1<span class="_ _10"> </span>范<span class="_ _2"></span>围</div><div class="t m0 x45 h5 y44 ff1 fs1 fc0 sc1 ls0 ws0">MODBUS<span class="_"> </span><span class="ff2">是<span class="_ _6"> </span></span>OSI<span class="_ _11"> </span><span class="ff2">模型第<span class="_ _6"> </span></span>7<span class="_"> </span><span class="ff2">层<span class="_ _2"></span>上的应用层报<span class="_ _2"></span>文传输<span class="_ _2"></span>协议，<span class="_ _12"></span>它在连接至<span class="_ _2"></span>不同类<span class="_ _2"></span>型总线或网<span class="_ _2"></span>络的设备</span></div><div class="t m0 x1 h5 y45 ff2 fs1 fc0 sc1 ls0 ws0">之间提供客户<span class="_ _2"></span>机<span class="ff1">/</span>服务器通信。</div><div class="t m0 x45 h5 y46 ff2 fs1 fc0 sc1 ls0 ws0">自从<span class="_ _6"> </span><span class="ff1">1979<span class="_"> </span></span>年<span class="_ _2"></span>出现工业<span class="_ _2"></span>串行链路的<span class="_ _2"></span>事实标准<span class="_ _2"></span>以来，<span class="_ _13"></span><span class="ff1">MODBUS<span class="_ _11"> </span><span class="ff2">使成千上万的自<span class="_ _2"></span>动化设<span class="_ _2"></span>备能够通信。</span></span></div><div class="t m0 x1 h5 y47 ff2 fs1 fc0 sc1 ls0 ws0">目前，<span class="_ _3"></span>继续增<span class="_ _2"></span>加对简单而<span class="_ _2"></span>雅观的<span class="_ _6"> </span><span class="ff1">MOD<span class="_ _2"></span>BUS<span class="_"> </span></span>结<span class="_ _2"></span>构支持。<span class="_ _3"></span>互联网<span class="_ _2"></span>组织能够使<span class="_ _11"> </span><span class="ff1">TCP/IP<span class="_"> </span></span>栈上的<span class="_ _2"></span>保留系统端</div><div class="t m0 x1 h5 y48 ff2 fs1 fc0 sc1 ls0 ws0">口<span class="_ _6"> </span><span class="ff1">502<span class="_"> </span></span>访问<span class="_ _6"> </span><span class="ff1">MOD<span class="_ _2"></span>BUS</span>。</div><div class="t m0 x45 h5 y49 ff1 fs1 fc0 sc1 ls0 ws0">MODBUS<span class="_ _11"> </span><span class="ff2">是一个<span class="_ _2"></span>请<span class="_ _2"></span>求<span class="_ _2"></span></span>/<span class="ff2">应<span class="_ _2"></span>答<span class="_ _2"></span>协议<span class="_ _2"></span>，<span class="_ _2"></span>并<span class="_ _2"></span>且提<span class="_ _2"></span>供功<span class="_ _2"></span>能<span class="_ _2"></span>码<span class="_ _2"></span>规<span class="_ _2"></span>定的<span class="_ _2"></span>服<span class="_ _2"></span>务。<span class="_ _2"></span></span>MOD<span class="_ _2"></span>BUS<span class="_ _11"> </span><span class="ff2">功能码<span class="_ _2"></span>是<span class="_ _11"> </span></span>MODBUS</div><div class="t m0 x1 h5 y4a ff2 fs1 fc0 sc1 ls0 ws0">请求<span class="ff1">/</span>应答<span class="_ _6"> </span><span class="ff1">PDU<span class="_ _11"> </span></span>的元素。本文件的<span class="_ _2"></span>作用是描述<span class="_ _6"> </span><span class="ff1">MOD<span class="_ _2"></span>BUS<span class="_"> </span></span>事务<span class="_ _2"></span>处理框架内使<span class="_ _2"></span>用的功能<span class="_ _2"></span>码。</div><div class="t m0 x1 h5 y4b ff2 fs1 fc0 sc0 ls0 ws0">1.2<span class="_ _10"> </span>规<span class="_ _2"></span>范性<span class="_ _2"></span>引用文<span class="_ _2"></span>件</div><div class="t m0 x45 h5 y4c ff1 fs1 fc0 sc1 ls0 ws0">1<span class="ff2">．</span>RFC791<span class="ff2">，互<span class="_ _2"></span>联网协议，<span class="_ _2"></span></span>Sep81<span class="_ _6"> </span>DA<span class="_ _2"></span>RP<span class="_ _14"></span>A</div><div class="t m0 x45 h5 y4d ff1 fs1 fc0 sc1 ls0 ws0">2<span class="ff2">．</span>MODBUS<span class="_ _6"> </span><span class="ff2">协议<span class="_ _2"></span>参考指南<span class="_ _15"> </span></span>Rev<span class="_"> </span>J,MODIC<span class="_ _2"></span>ON<span class="ff2">，</span>19<span class="_ _2"></span>96<span class="_"> </span><span class="ff2">年<span class="_ _6"> </span></span>6<span class="_"> </span><span class="ff2">月，</span>d<span class="_ _2"></span>oc#PI_MBUS_<span class="_ _2"></span>300</div><div class="t m0 x45 h5 y4e ff1 fs1 fc0 sc1 ls0 ws0">MODBUS<span class="_"> </span><span class="ff2">是<span class="_ _2"></span>一项应用<span class="_ _2"></span>层报文传输协<span class="_ _2"></span>议，<span class="_ _13"></span>用于在通过<span class="_ _2"></span>不同类型<span class="_ _2"></span>的总线<span class="_ _2"></span>或网络连接的<span class="_ _2"></span>设备之间的<span class="_ _2"></span>客</span></div><div class="t m0 x1 h5 y4f ff2 fs1 fc0 sc1 ls0 ws0">户机<span class="ff1">/</span>服务器通<span class="_ _2"></span>信。</div><div class="t m0 x45 h5 y50 ff2 fs1 fc0 sc1 ls0 ws0">目前，使用下<span class="_ _2"></span>列情况实现<span class="_ _6"> </span><span class="ff1">MOD<span class="_ _2"></span>BUS<span class="_ _2"></span></span>：</div><div class="t m0 x45 h5 y51 ff2 fs1 fc0 sc1 ls0 ws0">以太网上的<span class="_ _6"> </span><span class="ff1">TCP/IP<span class="_ _2"></span></span>。</div><div class="t m0 x45 h5 y52 ff2 fs1 fc0 sc1 ls0 ws0">各种媒体（有线：<span class="ff1">EIA/TIA-23<span class="_ _2"></span>2-E</span>、<span class="ff1">EIA-422</span>、<span class="ff1">EIA/TIA-485-A<span class="_ _2"></span></span>；光纤、无线等等）上的异步串<span class="_ _2"></span>行</div><div class="t m0 x1 h5 y53 ff2 fs1 fc0 sc1 ls0 ws0">传输。</div><div class="t m0 x45 h5 y54 ff1 fs1 fc0 sc1 ls0 ws0">MODBUS<span class="_"> </span>PLU<span class="_ _2"></span>S<span class="ff2">，一种高<span class="_ _2"></span>速令牌传递网<span class="_ _2"></span>络。</span></div><div class="c x46 y55 wf h13"><div class="t m2 x47 h14 y56 ff1 fs7 fc0 sc1 ls0 ws0"> </div></div><div class="c x48 y57 w10 h15"><div class="t m2 x2d h16 y58 ff1 fs8 fc0 sc1 ls0 ws0">MOD<span class="_ _2"></span>BUS<span class="_"> </span><span class="ff2">应用层</span><span class="fs7"> </span></div></div><div class="c x12 y59 w11 h17"><div class="t m2 x0 h18 y5a ff2 fs7 fc0 sc1 ls0 ws0">基于<span class="_ _b"> </span><span class="ff1">TCP<span class="_"> </span></span>的<span class="_ _c"> </span><span class="ff1">M<span class="_ _9"></span>odbus<span class="_ _2"></span><span class="fc1 sc1"> </span></span></div></div><div class="c x49 y5b w12 h15"><div class="t m2 x4a h14 y5c ff1 fs7 fc0 sc1 ls0 ws0">TCP </div></div><div class="c x49 y5d w12 h17"><div class="t m2 x4b h14 y5e ff1 fs7 fc0 sc1 ls0 ws0">IP </div></div><div class="c x48 y5f w13 h19"><div class="t m2 x26 h18 y60 ff2 fs7 fc0 sc1 ls0 ws0">其它<span class="ff1"> </span></div></div><div class="c x4c y5f w12 h19"><div class="t m2 x4d h14 y60 ff1 fs7 fc0 sc1 ls0 ws0">MODBUS+/HDL<span class="_ _3"></span> </div></div><div class="c x4e y5f w14 h19"><div class="t m2 x4f h18 y60 ff2 fs7 fc0 sc1 ls0 ws0">主站<span class="ff1">/</span>从<span class="_ _2"></span>站<span class="ff1"> </span></div></div><div class="c x49 y5f w12 h19"><div class="t m2 x50 h18 y60 ff2 fs7 fc0 sc1 ls0 ws0">以太网<span class="_ _6"> </span><span class="ff1">I<span class="_ _2"></span>I<span class="_ _2"></span>/802<span class="_ _3"></span>.3 </span></div></div><div class="c x48 y61 w13 h1a"><div class="t m2 x26 h18 y62 ff2 fs7 fc0 sc1 ls0 ws0">其它<span class="ff1"> </span></div></div><div class="c x4c y61 w12 h1a"><div class="t m2 x51 h18 y62 ff2 fs7 fc0 sc1 ls0 ws0">物理层<span class="_ _2"></span><span class="ff1"> </span></div></div><div class="c x4e y61 w14 h1a"><div class="t m2 x52 h18 y63 ff1 fs7 fc0 sc1 ls0 ws0">EI<span class="_ _2"></span>A/TIA-<span class="_ _3"></span>232<span class="_ _c"> </span><span class="ff2">或</span></div><div class="t m2 x53 h14 y64 ff1 fs7 fc0 sc1 ls0 ws0">EI<span class="_ _2"></span>A/TIA-<span class="_ _3"></span>485<span class="_ _3"></span> </div><div class="t m2 x0 h14 y65 ff1 fs7 fc0 sc1 ls0 ws0"><span class="fc1 sc1"> </span></div></div><div class="c x49 y61 w12 h1a"><div class="t m2 x26 h18 y62 ff2 fs7 fc0 sc1 ls0 ws0">以太网<span class="_ _2"></span>物理<span class="_ _2"></span>层<span class="ff1"> </span></div></div><div class="c x0 y36 we h0"><div class="t m0 x18 h5 y66 ff2 fs1 fc0 sc1 ls0 ws0">图<span class="_ _6"> </span>1：MODBUS<span class="_ _6"> </span>通信<span class="_ _2"></span>栈</div></div></div><div class="pi" data-data='{"ctm":[1.611830,0.000000,0.000000,1.611830,0.000000,0.000000]}'></div></div>

<div id="pf4" class="pf w0 h0" data-page-no="4"><div class="pc pc4 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/625232cb74bc5c0105bd3a96/bg4.jpg"><div class="t m0 x41 h2 y1 ff1 fs0 fc0 sc0 ls0 ws0">GB/T<span class="_ _0"> </span><span class="ff2">××××—××××</span></div><div class="c x42 y2 w2 h3"><div class="t m0 x3 h4 y3 ff1 fs0 fc0 sc1 ls0 ws0">3</div></div><div class="t m0 x44 h5 y67 ff1 fs1 fc0 sc0 ls0 ws0">2<span class="_ _10"> </span><span class="ff2">缩略语</span></div><div class="t m0 x1 h5 y68 ff1 fs1 fc0 sc1 ls0 ws0">ADU<span class="_ _1"> </span><span class="ff2">应用数据单元</span></div><div class="t m0 x1 h5 y69 ff1 fs1 fc0 sc1 ls0 ws0">HDLC<span class="_ _10"> </span><span class="ff2">高级数据<span class="_ _2"></span>链路控制</span></div><div class="t m0 x1 h5 y6a ff1 fs1 fc0 sc1 ls0 ws0">HMI<span class="_ _1"> </span><span class="ff2">人机界面</span></div><div class="t m0 x1 h5 y6b ff1 fs1 fc0 sc1 ls0 ws0">IETF<span class="_ _1"> </span><span class="ff2">因特网工程工<span class="_ _2"></span>作组</span></div><div class="t m0 x1 h5 y6c ff1 fs1 fc0 sc1 ls0 ws0">I/O<span class="_ _16"> </span><span class="ff2">输入</span>/<span class="ff2">输出设备</span></div><div class="t m0 x1 h5 y6d ff1 fs1 fc0 sc1 ls0 ws0">IP<span class="_ _17"> </span><span class="ff2">互连网协议</span></div><div class="t m0 x1 h5 y6e ff1 fs1 fc0 sc1 ls0 ws0">MAC<span class="_ _1"> </span><span class="ff2">介质访问控制</span></div><div class="t m0 x1 h5 y6f ff1 fs1 fc0 sc1 ls0 ws0">MB<span class="_ _16"> </span>MODBUS<span class="_ _11"> </span><span class="ff2">协议</span></div><div class="t m0 x1 h5 y46 ff1 fs1 fc0 sc1 ls0 ws0">MBAP<span class="_ _18"> </span>MODBUS<span class="_"> </span><span class="ff2">协议</span></div><div class="t m0 x1 h5 y70 ff1 fs1 fc0 sc1 ls0 ws0">PDU<span class="_ _19"> </span><span class="ff2">协议数据单元</span></div><div class="t m0 x1 h5 y71 ff1 fs1 fc0 sc1 ls0 ws0">PLC<span class="_ _19"> </span><span class="ff2">可编程逻辑控<span class="_ _2"></span>制器</span></div><div class="t m0 x1 h5 y72 ff1 fs1 fc0 sc1 ls0 ws0">TCP<span class="_ _1a"> </span><span class="ff2">传输控制协议</span></div><div class="t m0 x44 h5 y73 ff1 fs1 fc0 sc0 ls0 ws0">3<span class="_ _10"> </span><span class="ff2">背景概<span class="_ _2"></span>要</span></div><div class="t m0 x45 h5 y74 ff1 fs1 fc0 sc1 ls0 ws0">MODBUS<span class="_"> </span><span class="ff2">协议<span class="_ _2"></span>允许在各<span class="_ _2"></span>种网络体系结<span class="_ _2"></span>构内进行<span class="_ _2"></span>简单通信。</span></div><div class="c x3a y75 w15 h1b"><div class="t m3 x0 h1c y76 ff1 fs9 fc0 sc1 ls0 ws0">MODBU<span class="_ _3"></span>S </div><div class="t m3 x0 h1c y77 ff1 fs9 fc0 sc1 ls0 ws0">ON MB+<span class="fsa"> </span></div></div><div class="c x54 y78 w16 h1d"><div class="t m4 x55 h1e y79 ff1 fsb fc0 sc1 ls0 ws0">MODBUS ON RS232</div><div class="t m4 x55 h1f y7a ff1 fsc fc0 sc1 ls0 ws0"> </div></div><div class="c x56 y7b w16 h20"><div class="t m4 x55 h1e y7c ff1 fsb fc0 sc1 ls0 ws0">MODBUS ON RS485</div><div class="t m4 x55 h1f y7d ff1 fsc fc0 sc1 ls0 ws0"> </div></div><div class="c x57 y7e w17 h21"><div class="t m3 x0 h22 y7f ff1 fsa fc0 sc1 ls0 ws0"> </div></div><div class="c x58 y80 w18 h23"><div class="t m3 x0 h24 y81 ff2 fsa fc0 sc1 ls0 ws0">驱动器<span class="ff1"> </span></div></div><div class="c x59 y80 w19 h23"><div class="t m3 x0 h22 y81 ff1 fsa fc0 sc1 ls0 ws0">PL<span class="_ _3"></span>C </div></div><div class="c x5a y80 w19 h23"><div class="t m3 x0 h22 y81 ff1 fsa fc0 sc1 ls0 ws0">H<span class="_ _3"></span>MI </div></div><div class="c x5b y80 w19 h23"><div class="t m3 x0 h22 y81 ff1 fsa fc0 sc1 ls0 ws0">I/O </div></div><div class="c x56 y80 w19 h23"><div class="t m3 x0 h22 y81 ff1 fsa fc0 sc1 ls0 ws0">I/O </div></div><div class="c x5c y80 w19 h23"><div class="t m3 x0 h22 y81 ff1 fsa fc0 sc1 ls0 ws0">I/O </div></div><div class="c x49 y80 w19 h23"><div class="t m3 x0 h22 y81 ff1 fsa fc0 sc1 ls0 ws0">PL<span class="_ _3"></span>C </div></div><div class="c x1f y82 w1a h25"><div class="t m3 x0 h24 y83 ff2 fsa fc0 sc1 ls0 ws0">驱动器<span class="ff1"> </span></div></div><div class="c x1f y84 w19 h23"><div class="t m3 x0 h22 y85 ff1 fsa fc0 sc1 ls0 ws0">PL<span class="_ _3"></span>C </div></div><div class="c x1f y86 w19 h26"><div class="t m3 x0 h22 y87 ff1 fsa fc0 sc1 ls0 ws0">H<span class="_ _3"></span>MI </div></div><div class="c x1f y88 w19 h23"><div class="t m3 x0 h22 y89 ff1 fsa fc0 sc1 ls0 ws0">I/O </div></div><div class="c x5d y88 w1b h23"><div class="t m3 x0 h24 y89 ff2 fsa fc0 sc1 ls0 ws0">驱动器<span class="ff1"> </span></div></div><div class="c x5d y84 w19 h23"><div class="t m3 x0 h22 y85 ff1 fsa fc0 sc1 ls0 ws0">PL<span class="_ _3"></span>C </div></div><div class="c x5d y82 w19 h25"><div class="t m3 x0 h22 y83 ff1 fsa fc0 sc1 ls0 ws0">I/O </div></div><div class="c x5d y86 w19 h26"><div class="t m3 x0 h22 y87 ff1 fsa fc0 sc1 ls0 ws0">I/O </div></div><div class="c x5e y8a w1c h26"><div class="t m3 x0 h24 y8b ff2 fsa fc0 sc1 ls0 ws0">驱动器<span class="ff1"> </span></div></div><div class="c x5f y8c w19 h26"><div class="t m3 x0 h22 y8d ff1 fsa fc0 sc1 ls0 ws0">I/O </div></div><div class="c x60 y8e w1d h26"><div class="t m3 x0 h24 y8f ff2 fsa fc0 sc1 ls0 ws0">网关<span class="ff1"> </span></div></div><div class="c x61 y8e w1d h26"><div class="t m3 x0 h24 y8f ff2 fsa fc0 sc1 ls0 ws0">网关<span class="ff1"> </span></div></div><div class="c x62 y8e w1d h26"><div class="t m3 x0 h24 y8f ff2 fsa fc0 sc1 ls0 ws0">网关<span class="ff1"> </span></div></div><div class="c x63 y90 w1e h27"><div class="t m3 x64 h28 y91 ff1 fs9 fc0 sc1 ls0 ws0">MODBU<span class="_ _3"></span>S<span class="_"> </span><span class="ff2">通信</span><span class="fsa"> </span></div></div><div class="c x65 y92 w1f h29"><div class="t m3 x0 h22 y93 ff1 fsa fc0 sc1 ls0 ws0">MO<span class="_ _3"></span>DBUS O<span class="_ _14"></span>N TCP<span class="_ _3"></span>/IP </div></div><div class="c x0 y36 w20 h0"><div class="t m0 x66 h5 y94 ff2 fs1 fc0 sc1 ls0 ws0">图<span class="_ _6"> </span>2：MO<span class="_ _2"></span>DBUS<span class="_ _6"> </span>网络体系结构<span class="_ _2"></span>的实例</div><div class="t m0 x45 h5 y95 ff2 fs1 fc0 sc1 ls0 ws0">每种设备<span class="_ _3"></span>（<span class="ff1">PLC</span>、<span class="_ _3"></span><span class="ff1">HMI<span class="ff2">、<span class="_ _14"></span>控<span class="_ _2"></span>制面板、<span class="_ _3"></span>驱动程序、<span class="_ _3"></span>动作控<span class="_ _2"></span>制、<span class="_ _14"></span>输<span class="_ _2"></span>入<span class="ff1">/</span>输出设<span class="_ _2"></span>备）<span class="_ _14"></span>都<span class="_ _2"></span>能使用<span class="_ _6"> </span><span class="ff1">MOD<span class="_ _2"></span>BUS</span></span></span></div><div class="t m0 x1 h5 y96 ff2 fs1 fc0 sc1 ls0 ws0">协议来启动远<span class="_ _2"></span>程操作。</div><div class="t m0 x45 h5 y97 ff2 fs1 fc0 sc1 ls0 ws0">在基于串行链<span class="_ _2"></span>路和以太<span class="_ _6"> </span><span class="ff1">TCP/IP<span class="_ _11"> </span></span>网络的<span class="_ _6"> </span><span class="ff1">MODBUS<span class="_ _6"> </span></span>上可<span class="_ _2"></span>以进行相<span class="_ _2"></span>同通信。</div><div class="t m0 x45 h5 y98 ff2 fs1 fc0 sc1 ls0 ws0">一些网关允许<span class="_ _2"></span>在几种使用<span class="_ _6"> </span><span class="ff1">MOD<span class="_ _2"></span>BUS<span class="_"> </span></span>协议<span class="_ _2"></span>的总线或网络<span class="_ _2"></span>之间进行<span class="_ _2"></span>通信。</div></div></div><div class="pi" data-data='{"ctm":[1.611830,0.000000,0.000000,1.611830,0.000000,0.000000]}'></div></div>

<div id="pf5" class="pf w0 h0" data-page-no="5"><div class="pc pc5 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/625232cb74bc5c0105bd3a96/bg5.jpg"><div class="t m0 x1 h2 y1 ff1 fs0 fc0 sc0 ls0 ws0">GB/T<span class="_ _0"> </span><span class="ff2">××××—××××</span></div><div class="c x2 y2 w2 h3"><div class="t m0 x3 h4 y3 ff1 fs0 fc0 sc1 ls0 ws0">4</div></div><div class="t m0 x44 h5 y67 ff1 fs1 fc0 sc0 ls0 ws0">4<span class="_ _10"> </span><span class="ff2">总体描<span class="_ _2"></span>述</span></div><div class="t m0 x1 h5 y99 ff2 fs1 fc0 sc0 ls0 ws0">4.1<span class="_ _10"> </span>协<span class="_ _2"></span>议描<span class="_ _2"></span>述</div><div class="t m0 x45 h5 y9a ff1 fs1 fc0 sc1 ls0 ws0">MODBUS<span class="_"> </span><span class="ff2">协<span class="_ _2"></span>议定<span class="_ _2"></span>义了<span class="_ _2"></span>一个与<span class="_ _2"></span>基础<span class="_ _2"></span>通信层<span class="_ _2"></span>无关的<span class="_ _2"></span>简单<span class="_ _2"></span>协议<span class="_ _2"></span>数据单<span class="_ _2"></span>元（<span class="_ _2"></span></span>PDU<span class="_ _2"></span><span class="ff2">）<span class="_ _1b"></span>。特定<span class="_ _2"></span>总线<span class="_ _2"></span>或网<span class="_ _2"></span>络上</span></div><div class="t m0 x1 h5 y9b ff2 fs1 fc0 sc1 ls0 ws0">的<span class="_ _6"> </span><span class="ff1">MODBUS<span class="_"> </span></span>协议<span class="_ _2"></span>映射能够在应<span class="_ _2"></span>用数据单<span class="_ _2"></span>元（<span class="ff1">ADU<span class="_ _2"></span></span>）上引入<span class="_ _2"></span>一些附加域。</div><div class="c x2b y9c w21 h2a"><div class="t m5 x0 h2b y9d ff1 fsd fc0 sc1 ls0 ws0"> </div></div><div class="c xa y9e w22 h2c"><div class="t m5 x67 h2d y9f ff2 fse fc0 sc1 ls0 ws0">地址域</div><div class="t m5 x68 h2e ya0 ff4 fse fc0 sc1 ls0 ws0"> </div></div><div class="c x69 y9e w23 h2c"><div class="t m5 x6a h2d y9f ff2 fse fc0 sc1 ls0 ws0">功能码</div><div class="t m5 x6b h2e ya0 ff4 fse fc0 sc1 ls0 ws0"> </div></div><div class="c x61 y9e w24 h2c"><div class="t m5 x6c h2d y9f ff2 fse fc0 sc1 ls0 ws0">数据</div><div class="t m5 x6d h2e ya0 ff4 fse fc0 sc1 ls0 ws0"> </div></div><div class="c x6e y9e w25 h2c"><div class="t m5 x6f h2d y9f ff2 fse fc0 sc1 ls0 ws0">差错校验</div><div class="t m5 x70 h2e ya0 ff4 fse fc0 sc1 ls0 ws0"> </div></div><div class="c x71 ya1 w26 h2f"><div class="t m5 x72 h2e ya2 ff4 fse fc0 sc0 ls0 ws0">A<span class="_ _c"> </span>D<span class="_ _c"> </span>U<span class="_ _b"> </span> </div></div><div class="c x73 ya3 w27 h2f"><div class="t m5 x4a h2e ya4 ff4 fse fc0 sc0 ls0 ws0">P<span class="_ _1c"> </span>D<span class="_ _c"> </span>U<span class="_ _c"> </span> </div></div><div class="c x0 y36 w28 h0"><div class="t m0 x74 h5 ya5 ff2 fs1 fc0 sc1 ls0 ws0">图<span class="_ _6"> </span>3：通用<span class="_ _6"> </span>MOD<span class="_ _2"></span>BUS<span class="_ _6"> </span>帧</div><div class="t m0 x45 h5 ya6 ff2 fs1 fc0 sc1 ls0 ws0">启动<span class="_ _6"> </span><span class="ff1">MODBUS<span class="_ _11"> </span></span>事务处理的客<span class="_ _2"></span>户机创建<span class="_ _6"> </span><span class="ff1">MOD<span class="_ _2"></span>BUS<span class="_"> </span></span>应<span class="_ _2"></span>用数据单<span class="_ _2"></span>元。<span class="_ _13"></span>功能码向服务<span class="_ _2"></span>器指示将执<span class="_ _2"></span>行哪</div><div class="t m0 x1 h5 ya7 ff2 fs1 fc0 sc1 ls0 ws0">种操作。</div><div class="t m0 x45 h5 ya8 ff1 fs1 fc0 sc1 ls0 ws0">MODBUS<span class="_"> </span><span class="ff2">协议<span class="_ _2"></span>建立了客<span class="_ _2"></span>户机启动的请<span class="_ _2"></span>求格式。</span></div><div class="t m0 x45 h5 ya9 ff2 fs1 fc0 sc1 ls0 ws0">用一<span class="_ _2"></span>个字<span class="_ _2"></span>节编<span class="_ _2"></span>码<span class="_ _6"> </span><span class="ff1">MODBUS<span class="_ _11"> </span></span>数据<span class="_ _2"></span>单元<span class="_ _2"></span>的功<span class="_ _2"></span>能<span class="_ _2"></span>码域<span class="_ _2"></span>。有<span class="_ _2"></span>效的<span class="_ _2"></span>码<span class="_ _2"></span>字范<span class="_ _2"></span>围是<span class="_ _2"></span>十进<span class="_ _2"></span>制<span class="_ _6"> </span><span class="ff1">1-255<span class="_ _2"></span></span>（<span class="_ _2"></span><span class="ff1">128<span class="_ _2"></span>-255<span class="_"> </span></span>为</div><div class="t m0 x1 h5 yaa ff2 fs1 fc0 sc1 ls0 ws0">异常响应保留<span class="_ _2"></span>）<span class="_ _1b"></span>。当从客户机<span class="_ _2"></span>向服务器设备<span class="_ _2"></span>发送报文<span class="_ _2"></span>时，功能码域<span class="_ _2"></span>通知服务<span class="_ _2"></span>器执行哪种操<span class="_ _2"></span>作。</div><div class="t m0 x45 h5 yab ff2 fs1 fc0 sc1 ls0 ws0">向一些功能码<span class="_ _2"></span>加入子功能码<span class="_ _2"></span>来定义多<span class="_ _2"></span>项操作。</div><div class="t m0 x45 h5 yac ff2 fs1 fc0 sc1 ls0 ws0">从客户<span class="_ _2"></span>机向<span class="_ _2"></span>服务器<span class="_ _2"></span>设备发<span class="_ _2"></span>送的<span class="_ _2"></span>报文<span class="_ _2"></span>数据域包<span class="_ _2"></span>括附<span class="_ _2"></span>加信<span class="_ _2"></span>息，服<span class="_ _2"></span>务器<span class="_ _2"></span>使用这<span class="_ _2"></span>个信息<span class="_ _2"></span>执行<span class="_ _2"></span>功能<span class="_ _2"></span>码定<span class="_ _2"></span>义</div><div class="t m0 x1 h5 yad ff2 fs1 fc0 sc1 ls0 ws0">的操作。这个<span class="_ _2"></span>域还包括离散<span class="_ _2"></span>项目和寄<span class="_ _2"></span>存器地址、处<span class="_ _2"></span>理的项目<span class="_ _2"></span>数量以及域中<span class="_ _2"></span>的实际数<span class="_ _2"></span>据字节数。</div><div class="t m0 x45 h5 yae ff2 fs1 fc0 sc1 ls0 ws0">在某种请求<span class="_ _2"></span>中，数据<span class="_ _2"></span>域可以是不存<span class="_ _2"></span>在的（<span class="ff1">0<span class="_"> </span></span>长度<span class="_ _2"></span>）<span class="_ _1b"></span>，在此情况下服<span class="_ _2"></span>务器不需<span class="_ _2"></span>要任何附加信<span class="_ _2"></span>息。<span class="_ _14"></span>功</div><div class="t m0 x1 h5 yaf ff2 fs1 fc0 sc1 ls0 ws0">能码仅说明操<span class="_ _2"></span>作。</div><div class="t m0 x45 h5 yb0 ff2 fs1 fc0 sc1 ls0 ws0">如果<span class="_ _2"></span>在一<span class="_ _2"></span>个<span class="_ _2"></span>正确<span class="_ _2"></span>接收<span class="_ _2"></span>的<span class="_ _11"> </span><span class="ff1">MODBUS<span class="_ _b"> </span>ADU<span class="_"> </span></span>中<span class="_ _2"></span>，不<span class="_ _2"></span>出<span class="_ _2"></span>现与<span class="_ _2"></span>请<span class="_ _2"></span>求<span class="_ _6"> </span><span class="ff1">MODBUS<span class="_ _11"> </span></span>功能<span class="_ _2"></span>有关<span class="_ _2"></span>的<span class="_ _2"></span>差错<span class="_ _2"></span>，<span class="_ _2"></span>那么<span class="_ _2"></span>服</div><div class="t m0 x1 h5 yb1 ff2 fs1 fc0 sc1 ls0 ws0">务器<span class="_ _2"></span>至客<span class="_ _2"></span>户<span class="_ _2"></span>机<span class="_ _2"></span>的响<span class="_ _2"></span>应数<span class="_ _2"></span>据<span class="_ _2"></span>域<span class="_ _2"></span>包括<span class="_ _2"></span>请求<span class="_ _2"></span>数<span class="_ _2"></span>据<span class="_ _2"></span>。如<span class="_ _2"></span>果出<span class="_ _2"></span>现<span class="_ _2"></span>与<span class="_ _2"></span>请求<span class="_ _11"> </span><span class="ff1">MODBUS<span class="_"> </span></span>功<span class="_ _2"></span>能<span class="_ _2"></span>有关<span class="_ _2"></span>的<span class="_ _2"></span>差错<span class="_ _2"></span>，<span class="_ _2"></span>那么<span class="_ _2"></span>域<span class="_ _2"></span>包</div><div class="t m0 x1 h5 yb2 ff2 fs1 fc0 sc1 ls0 ws0">括一个异常码<span class="_ _2"></span>，服务器应用<span class="_ _2"></span>能够使用<span class="_ _2"></span>这个域确定下<span class="_ _2"></span>一个执行<span class="_ _2"></span>的操作。</div><div class="t m0 x45 h5 yb3 ff2 fs1 fc0 sc1 ls0 ws0">例如，<span class="_ _1d"></span>客户机能够<span class="_ _2"></span>读一组离<span class="_ _2"></span>散量输出或输<span class="_ _2"></span>入的开<span class="ff1">/<span class="_ _2"></span></span>关状态，<span class="_ _1d"></span>或者客<span class="_ _2"></span>户机能够<span class="_ _2"></span>读<span class="ff1">/</span>写一组寄存<span class="_ _2"></span>器的数</div><div class="t m0 x1 h5 yb4 ff2 fs1 fc0 sc1 ls0 ws0">据内容。</div><div class="t m0 x45 h5 yb5 ff2 fs1 fc0 sc1 ls0 ws0">当服务<span class="_ _2"></span>器对<span class="_ _2"></span>客户机<span class="_ _2"></span>响应时<span class="_ _2"></span>，它<span class="_ _2"></span>使用<span class="_ _2"></span>功能码域<span class="_ _2"></span>来指<span class="_ _2"></span>示正<span class="_ _2"></span>常（无<span class="_ _2"></span>差错<span class="_ _2"></span>）响应<span class="_ _2"></span>或者出<span class="_ _2"></span>现某<span class="_ _2"></span>种差<span class="_ _2"></span>错（<span class="_ _2"></span>称</div><div class="t m0 x1 h5 yb6 ff2 fs1 fc0 sc1 ls0 ws0">为异常响应）<span class="_ _1b"></span>。对于一<span class="_ _2"></span>个正常响<span class="_ _2"></span>应来说，服务<span class="_ _2"></span>器仅对原<span class="_ _2"></span>始功能码响应<span class="_ _2"></span>。</div></div><div class="c x75 yb7 w29 h30"><div class="t m6 x0 h31 yb8 ff1 fsf fc0 sc1 ls0 ws0"> </div></div><div class="c x15 yb9 w2a h32"><div class="t m6 x0 h33 yba ff2 fsf fc0 sc1 ls0 ws0">启<span class="_ _2"></span>动<span class="_ _9"></span>请<span class="_ _2"></span>求<span class="_ _9"></span><span class="ff1"> </span></div></div><div class="c x76 ybb w2a h32"><div class="t m6 x0 h33 ybc ff2 fsf fc0 sc1 ls0 ws0">功<span class="_ _2"></span>能<span class="_ _9"></span>码<span class="_ _2"></span><span class="ff1"> </span></div></div><div class="c x77 ybb w2b h32"><div class="t m6 x0 h33 ybc ff2 fsf fc0 sc1 ls0 ws0">数<span class="_ _2"></span>据<span class="_ _9"></span>请<span class="_ _2"></span>求<span class="_ _9"></span><span class="ff1"> </span></div></div><div class="c x56 ybd w2b h32"><div class="t m6 x0 h33 ybe ff2 fsf fc0 sc1 ls0 ws0">操<span class="_ _2"></span>作<span class="_ _9"></span>码<span class="_ _2"></span><span class="ff1"> </span></div></div><div class="c x15 ybf w2a h32"><div class="t m6 x0 h33 yc0 ff2 fsf fc0 sc1 ls0 ws0">接<span class="_ _2"></span>收<span class="_ _9"></span>响<span class="_ _2"></span>应<span class="_ _9"></span><span class="ff1"> </span></div></div><div class="c x78 ybd w2b h32"><div class="t m6 x0 h33 ybe ff2 fsf fc0 sc1 ls0 ws0">数<span class="_ _2"></span>据<span class="_ _9"></span>响<span class="_ _2"></span>应<span class="_ _9"></span><span class="ff1"> </span></div></div><div class="c x28 yc1 w2c h34"><div class="t m6 x0 h33 yc2 ff2 fsf fc0 sc1 ls0 ws0">执<span class="_ _2"></span>行<span class="_ _9"></span>操<span class="_ _2"></span>作<span class="_ _9"></span><span class="ff1"> </span></div><div class="t m6 x0 h33 yc3 ff2 fsf fc0 sc1 ls0 ws0">启<span class="_ _2"></span>动<span class="_ _9"></span>响<span class="_ _2"></span>应<span class="_ _9"></span><span class="ff1"> </span></div></div><div class="c x36 yc4 w2d h35"><div class="t m6 x0 h33 yc5 ff2 fsf fc0 sc1 ls0 ws0">客<span class="_ _2"></span>户<span class="_ _9"></span>机<span class="_ _2"></span><span class="ff1"> </span></div></div><div class="c x79 yc6 w2d h35"><div class="t m6 x0 h33 yc7 ff2 fsf fc0 sc1 ls0 ws0">服<span class="_ _2"></span>务<span class="_ _9"></span>器<span class="_ _2"></span><span class="ff1"> </span></div></div><div class="c x0 y36 w2e h0"><div class="t m0 x66 h5 yc8 ff2 fs1 fc0 sc1 ls0 ws0">图<span class="_ _6"> </span>4：MO<span class="_ _2"></span>DBUS<span class="_ _6"> </span>事务处理（无<span class="_ _2"></span>差错）</div><div class="t m0 x45 h5 yc9 ff2 fs1 fc0 sc1 ls0 ws0">对于异<span class="_ _2"></span>常响<span class="_ _2"></span>应，服<span class="_ _2"></span>务器返<span class="_ _2"></span>回一<span class="_ _2"></span>个与<span class="_ _2"></span>原始功能<span class="_ _2"></span>码等<span class="_ _2"></span>同的<span class="_ _2"></span>码，设<span class="_ _2"></span>置该<span class="_ _2"></span>原始功<span class="_ _2"></span>能码的<span class="_ _2"></span>最高<span class="_ _2"></span>有效<span class="_ _2"></span>位为<span class="_ _2"></span>逻</div><div class="t m0 x1 h5 yca ff2 fs1 fc0 sc1 ls0 ws0">辑<span class="_ _6"> </span><span class="ff1">1</span>。</div></div></div><div class="pi" data-data='{"ctm":[1.611830,0.000000,0.000000,1.611830,0.000000,0.000000]}'></div></div>