http://wiki.jackslab.org/index.php?action=history&feed=atom&title=RS485 2026-08-12T09:59:43Z 本wiki的该页面的版本历史 MediaWiki 1.19.2 http://wiki.jackslab.org/index.php?title=RS485&diff=9192&oldid=prev 2017-10-26T02:49:48Z

<p>‎<span dir="auto"><span class="autocomment">Notes</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2017年10月26日 (四) 02:49的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第84行：</td> <td colspan="2" class="diff-lineno">第84行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>&lt;br&gt;</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>&lt;br&gt;</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">== 终端电阻 ==</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">一般在设备少距离短的情况下，不加终端负载电阻，整个网络也能很好的工作，但随着距离的增加性能将降低。</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">一般建议在通信距离超过 100米时，要在485通讯的开始端和结束端增加终端电阻，阻值大小一般为 120 欧姆</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">这种匹配方法简单有效，但有一个缺点，匹配电阻要消耗较大功率，对于功耗限制比较严格的系统不太适合。另外一种比较省电的匹配方式是RC匹配。利用一只电容C隔断直流成分可以节省大部分功率。但电容C的取值是个难点，需要在功耗和匹配质量间进行折衷。 还有一种采用二极管的匹配方法，这种方案虽未实现真正的“匹配”，但它利用二极管的钳位作用能迅速削弱反射信号，达到改善信号质量的目的，节能效果显著</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">判断在什么样的数据速率和电缆长度时需要进行匹配，MAXIM 有条经验性的原则：当信号的转换时间（上升或下降时间）超过电信号沿总线单向传输所需时间的3倍以上时就可以不加匹配。</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">&lt;br&gt;&lt;br&gt;</ins></div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>== Notes ==</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>== Notes ==</div></td></tr> </table>

Comcat http://wiki.jackslab.org/index.php?title=RS485&diff=9191&oldid=prev 2017-10-26T02:27:56Z

<p>‎<span dir="auto"><span class="autocomment">走线建议</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2017年10月26日 (四) 02:27的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第75行：</td> <td colspan="2" class="diff-lineno">第75行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>=== 走线建议 ===</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>=== 走线建议 ===</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline"> </del>工程现场走线应遵循两个原则：</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>工程现场走线应遵循两个原则：</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*&#160; 远离电源线，日光灯等干扰源，应尽量远离高压电线，不要与电源线并行，更不能捆扎在一起</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*&#160; 远离电源线，日光灯等干扰源，应尽量远离高压电线，不要与电源线并行，更不能捆扎在一起</div></td></tr> </table>

Comcat http://wiki.jackslab.org/index.php?title=RS485&diff=9190&oldid=prev 2017-10-26T02:27:47Z

<p>‎<span dir="auto"><span class="autocomment">接地</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2017年10月26日 (四) 02:27的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第71行：</td> <td colspan="2" class="diff-lineno">第71行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>::发送驱动器输出信号中的共模部分需要一个返回通路，如没有一个低阻的返回通道（信号地），就会以辐射的形式返回源端，整个总线就会像一个巨大的天线向外辐射电磁波</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>::发送驱动器输出信号中的共模部分需要一个返回通路，如没有一个低阻的返回通道（信号地），就会以辐射的形式返回源端，整个总线就会像一个巨大的天线向外辐射电磁波</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div>&lt;br&gt;&lt;br&gt;</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>&lt;br&gt;</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>&#160;</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">=== 走线建议 ===</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>&#160;</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline"> 工程现场走线应遵循两个原则：</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>&#160;</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">*&#160; 远离电源线，日光灯等干扰源，应尽量远离高压电线，不要与电源线并行，更不能捆扎在一起</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">* 当网线不能与电源线等干扰源避开时，网线应与电源线垂直，不能平行，并采用质量高的双绞线走线</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>&#160;</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>&#160;</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">不可为了走线方便，把网线放在电源线的线槽里，或在天花板走线时经过日光灯等干扰源。实际上干扰源对相邻网线的干扰，主要是通过磁场和电场的作用，按照电磁理论，干扰源对网线的感应与距离的平方成反比，因此，网线离干扰源那怕远离10厘米，网线受到的干扰都会明显减弱</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>&#160;</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>&lt;br&gt;</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>== Notes ==</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>== Notes ==</div></td></tr> </table>

Comcat http://wiki.jackslab.org/index.php?title=RS485&diff=9189&oldid=prev 2017-10-26T02:23:41Z

<p>‎<span dir="auto"><span class="autocomment">共模干扰</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2017年10月26日 (四) 02:23的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第42行：</td> <td colspan="2" class="diff-lineno">第42行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>共模干扰是在信号线与地之间传输，属于非对称性干扰。</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>共模干扰是在信号线与地之间传输，属于非对称性干扰。</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>消除共模干扰的方法包括：</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>消除共模干扰的方法包括：</div></td></tr> </table>

Comcat http://wiki.jackslab.org/index.php?title=RS485&diff=9188&oldid=prev 2017-10-26T02:23:27Z

<p>‎<span dir="auto"><span class="autocomment">共模干扰</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2017年10月26日 (四) 02:23的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第45行：</td> <td colspan="2" class="diff-lineno">第45行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>消除共模干扰的方法包括：</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>消除共模干扰的方法包括：</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">（1）采用屏蔽双绞线并有效接地</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">* 采用屏蔽双绞线并有效接地</ins></div></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">（2）强电场的地方还要考虑采用镀锌管屏蔽</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">* 强电场的地方还要考虑采用镀锌管屏蔽</ins></div></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">（3）布线时远离高压线，更不能将高压电源线和信号线捆在一起走线 </del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">* 布线时远离高压线，更不能将高压电源线和信号线捆在一起走线 </ins></div></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">（4）不要和电控锁共用同一个电源</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">* 不要和电控锁共用同一个电源</ins></div></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del class="diffchange diffchange-inline">（5）采用线性稳压电源或高品质的开关电源</del>(纹波干扰小于50mV)</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">* 采用线性稳压电源或高品质的开关电源</ins>(纹波干扰小于50mV)</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>&lt;br&gt;</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>&lt;br&gt;</div></td></tr> </table>

Comcat http://wiki.jackslab.org/index.php?title=RS485&diff=9187&oldid=prev 2017-10-26T02:21:40Z

<p>‎<span dir="auto"><span class="autocomment">干扰防护</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2017年10月26日 (四) 02:21的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第28行：</td> <td colspan="2" class="diff-lineno">第28行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>== 干扰防护 ==</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>== 干扰防护 ==</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">485 通信线由两根双绞的线组成，它是通过两根通信线之间的电压差的方式来传递信号，因此称之为差分电压传输</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">=== 差模干扰 ===</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">差模干扰在两根信号线之间传输，属于对称性干扰。</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">消除差模干扰的方法是在电路中增加一个偏值电阻，并采用双绞线</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">&lt;br&gt;</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">=== 共模干扰 ===</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">共模干扰是在信号线与地之间传输，属于非对称性干扰。</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">消除共模干扰的方法包括：</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">（1）采用屏蔽双绞线并有效接地</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">（2）强电场的地方还要考虑采用镀锌管屏蔽</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">（3）布线时远离高压线，更不能将高压电源线和信号线捆在一起走线 </ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">（4）不要和电控锁共用同一个电源</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">（5）采用线性稳压电源或高品质的开关电源(纹波干扰小于50mV)</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">&lt;br&gt;</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">=== 接地 ===</ins></div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>很多情况下，连接 RS485 通信链路时只是简单地用一对双绞线将各个接口的“A”、“B”端连接起来。而忽略了信号地的连接，这种连接方法在许多场合是能正常工作的，但却埋下了很大的隐患，这有二个原因:</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>很多情况下，连接 RS485 通信链路时只是简单地用一对双绞线将各个接口的“A”、“B”端连接起来。而忽略了信号地的连接，这种连接方法在许多场合是能正常工作的，但却埋下了很大的隐患，这有二个原因:</div></td></tr> <tr><td colspan="2" class="diff-lineno">第33行：</td> <td colspan="2" class="diff-lineno">第59行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>* 共模干扰</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>* 共模干扰</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div>::RS485 <del class="diffchange diffchange-inline">接口采用差分方式传输信号方式，并不需要相对于某个参照点来检测信号，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，RS-485收发器共模电压范围为 </del>-7～+<del class="diffchange diffchange-inline">12V，只有满足上述条件，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，甚至损坏接口</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>::RS485 <ins class="diffchange diffchange-inline">接口采用差分方式传输信号方式，并不需要相对于某个参照点来检测信号，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，RS485 收发器共模电压范围为 </ins>-7～+<ins class="diffchange diffchange-inline">12V，只有满足上述条件，整个网络才能正常工作（否则网络不稳定）</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>&#160;</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">::共模干扰会增大上述共模电压。消除共模干扰的有效手段之一是将 485 通讯线的屏蔽层用作地线，将机具、电脑等网络中的设备地连接在一起，并由一点可靠地接入大地。</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>&#160;</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">::目前，有相当部分 PC 机在使用时，电源并没接地。主要是电源没有接地，或电源插座没有地线，从而造成PC机地线与地之间往往有几十伏以上的漏电电压存在，这个电压很容易就引入设备中，从而导致网卡或通讯口损坏。</ins></div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> </table>

Comcat http://wiki.jackslab.org/index.php?title=RS485&diff=9184&oldid=prev 2017-10-26T02:14:17Z

<p>‎<span dir="auto"><span class="autocomment">干扰防护</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2017年10月26日 (四) 02:14的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第28行：</td> <td colspan="2" class="diff-lineno">第28行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>== 干扰防护 ==</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>== 干扰防护 ==</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">很多情况下，连接 RS485 通信链路时只是简单地用一对双绞线将各个接口的“A”、“B”端连接起来。而忽略了信号地的连接，这种连接方法在许多场合是能正常工作的，但却埋下了很大的隐患，这有二个原因:</ins></div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>* 共模干扰</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>* 共模干扰</div></td></tr> </table>

Comcat http://wiki.jackslab.org/index.php?title=RS485&diff=9183&oldid=prev 2017-10-26T02:13:09Z

<p>‎<span dir="auto"><span class="autocomment">干扰防护</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2017年10月26日 (四) 02:13的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第32行：</td> <td colspan="2" class="diff-lineno">第32行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>::RS485 接口采用差分方式传输信号方式，并不需要相对于某个参照点来检测信号，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，RS-485收发器共模电压范围为 -7～+12V，只有满足上述条件，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，甚至损坏接口</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>::RS485 接口采用差分方式传输信号方式，并不需要相对于某个参照点来检测信号，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，RS-485收发器共模电压范围为 -7～+12V，只有满足上述条件，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，甚至损坏接口</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>* EMI 问题</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>* EMI 问题</div></td></tr> </table>

Comcat http://wiki.jackslab.org/index.php?title=RS485&diff=9182&oldid=prev 2017-10-26T02:12:59Z

<p>‎<span dir="auto"><span class="autocomment">干扰防护</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2017年10月26日 (四) 02:12的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第28行：</td> <td colspan="2" class="diff-lineno">第28行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>== 干扰防护 ==</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>== 干扰防护 ==</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">* 共模干扰</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">::RS485 接口采用差分方式传输信号方式，并不需要相对于某个参照点来检测信号，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，RS-485收发器共模电压范围为 -7～+12V，只有满足上述条件，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，甚至损坏接口</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">* EMI 问题</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">::发送驱动器输出信号中的共模部分需要一个返回通路，如没有一个低阻的返回通道（信号地），就会以辐射的形式返回源端，整个总线就会像一个巨大的天线向外辐射电磁波</ins></div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>&lt;br&gt;&lt;br&gt;</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>&lt;br&gt;&lt;br&gt;</div></td></tr> </table>

Comcat http://wiki.jackslab.org/index.php?title=RS485&diff=9176&oldid=prev 2017-10-26T01:49:28Z

<p>‎<span dir="auto"><span class="autocomment">Overview</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2017年10月26日 (四) 01:49的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第24行：</td> <td colspan="2" class="diff-lineno">第24行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>* 网络线为单股的铜线，相比多芯线而言容易断裂</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>* 网络线为单股的铜线，相比多芯线而言容易断裂</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*&#160; 5 类普通网线没有屏蔽层，不能防止共模干扰</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*&#160; 5 类普通网线没有屏蔽层，不能防止共模干扰</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">&lt;br&gt;&lt;br&gt;</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">== 干扰防护 ==</ins></div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>&lt;br&gt;&lt;br&gt;</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>&lt;br&gt;&lt;br&gt;</div></td></tr> </table>

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