"# Modbus \u4e32\u884c\u7ebf\u901a\u4fe1\u5b9e\u6218\u6307\u5357\uff1aRS-485 \u63a5\u7ebf\u3001\u7ec8\u7aef\u7535\u963b\u4e0e\u504f\u7f6e\u7535\u963b\u914d\u7f6e\u624b\u518c\n\n> 2026-06-28 | 2026-06-28\n> https:\/\/www.modbus.cn\/en\/44507.html\n\n**\u672a\u5206\u7c7b**\n\n---\n\nModbus \u4e32\u884c\u7ebf\u901a\u4fe1\u5b9e\u6218\u6307\u5357\uff1aRS-485 \u63a5\u7ebf\u3001\u7ec8\u7aef\u7535\u963b\u4e0e\u504f\u7f6e\u7535\u963b\u7684\u7ec8\u6781\u914d\u7f6e\u624b\u518c\n\n**\u5173\u952e\u8bcd\uff1a**RS-485 \u63a5\u7ebf\u3001Modbus \u4e32\u884c\u7ebf\u3001\u7ec8\u7aef\u7535\u963b 120\u03a9\u3001\u504f\u7f6e\u7535\u963b\u3001RS-485 \u6545\u969c\u6392\u67e5\u3001\u83ca\u82b1\u94fe\u62d3\u6251\n\n\u5728 Modbus \u901a\u4fe1\u6545\u969c\u4e2d\uff0c\u81f3\u5c11\u6709 60% \u7684\u95ee\u9898\u51fa\u5728\u7269\u7406\u5c42\u2014\u2014\u63a5\u7ebf\u9519\u8bef\u3001\u7ec8\u7aef\u7535\u963b\u7f3a\u5931\u3001\u504f\u7f6e\u7535\u963b\u914d\u7f6e\u4e0d\u5f53\u3001\u63a5\u5730\u4e0d\u826f\u3002\u7136\u800c\uff0c\u5927\u591a\u6570 Modbus \u6559\u7a0b\u90fd\u76f4\u63a5\u8df3\u5230\u534f\u8bae\u62a5\u6587\u5c42\u9762\uff0c\u5bf9\u300c\u600e\u4e48\u63a5\u7ebf\u300d\u300c\u7535\u963b\u600e\u4e48\u9009\u300d\u300c\u4e3a\u4ec0\u4e48\u901a\u4fe1\u65f6\u597d\u65f6\u574f\u300d\u8fd9\u4e9b\u5de5\u7a0b\u5e08\u6700\u5934\u75bc\u7684\u95ee\u9898\u4e00\u7b14\u5e26\u8fc7\u3002\n\n\u672c\u6587\u4ece\u7535\u5de5\u7684\u89c6\u89d2\u51fa\u53d1\uff0c\u7528\u4f60\u53ef\u4ee5\u76f4\u63a5\u5e26\u5230\u73b0\u573a\u64cd\u4f5c\u7684\u5b9e\u6218\u8bed\u8a00\uff0c\u628a RS-485 \u5e03\u7ebf\u7684\u6bcf\u4e00\u4e2a\u7ec6\u8282\u8bb2\u900f\u3002\u8bfb\u5b8c\u8fd9\u7bc7\u6587\u7ae0\uff0c\u4f60\u5c06\u80fd\u591f\u72ec\u7acb\u6392\u67e5\u548c\u89e3\u51b3 95% \u7684 Modbus \u4e32\u884c\u7ebf\u901a\u4fe1\u95ee\u9898\u3002\n\n## \u4e00\u3001RS-485 \u7535\u6c14\u57fa\u7840\uff1a\u5dee\u5206\u4fe1\u53f7\u7684\u9b54\u6cd5\n\n![RS-485 \u6b63\u786e\u4e0e\u9519\u8bef\u62d3\u6251\u5bf9\u6bd4](https:\/\/www.modbus.cn\/wp-content\/uploads\/diagrams\/a04-rs485-topology.svg)\u25b2 \u56fe1\uff1a\u83ca\u82b1\u94fe\uff08\u6b63\u786e\uff09vs \u661f\u578b\/\u957f\u5206\u652f\uff08\u9519\u8bef\uff09\u62d3\u6251\u5bf9\u6bd4\uff0c\u542b\u504f\u7f6e\u7535\u963b\u7f51\u7edc\u3002\n\n### 1.1 \u4e3a\u4ec0\u4e48\u662f\u5dee\u5206\u4fe1\u53f7\uff1f\n\nRS-232 \u4f7f\u7528\u5355\u7aef\u4fe1\u53f7\uff08\u4e00\u6839\u4fe1\u53f7\u7ebf + \u4e00\u6839\u5730\u7ebf\uff09\uff0c\u4fe1\u53f7\u7535\u538b\u4ee5\u5730\u7ebf\u4e3a\u53c2\u8003\u3002\u5f53\u5730\u7ebf\u4e0a\u7684\u5e72\u6270\u566a\u58f0\u8fbe\u5230\u4e00\u5b9a\u5e45\u5ea6\u65f6\uff0c\u63a5\u6536\u7aef\u5c31\u65e0\u6cd5\u6b63\u786e\u5224\u65ad\u903b\u8f91\u7535\u5e73\u3002\u8fd9\u662f RS-232 \u901a\u4fe1\u8ddd\u79bb\u77ed\uff08\u901a\u5e38 \u226415 \u7c73\uff09\u3001\u901f\u7387\u4f4e\uff08\u2264115200bps\uff09\u7684\u6839\u672c\u539f\u56e0\u3002\n\nRS-485 \u4f7f\u7528\u5dee\u5206\u4fe1\u53f7\uff1a\u7528\u4e24\u6839\u7ebf\uff08A \u548c B\uff09\u4f20\u8f93\u4e92\u4e3a\u53cd\u76f8\u7684\u4fe1\u53f7\u3002\u63a5\u6536\u7aef\u6d4b\u91cf\u7684\u662f A \u7ebf\u548c B \u7ebf\u4e4b\u95f4\u7684\u7535\u538b\u5dee\uff0c\u800c\u5171\u6a21\u566a\u58f0\u5728\u4e24\u6839\u7ebf\u4e0a\u4ea7\u751f\u7684\u5e72\u6270\u5e45\u5ea6\u57fa\u672c\u76f8\u540c\uff0c\u76f8\u51cf\u540e\u5c31\u62b5\u6d88\u4e86\u3002\u8fd9\u5c31\u662f RS-485 \u80fd\u591f\u5728 1200 \u7c73\u8ddd\u79bb\u4e0a\u53ef\u9760\u901a\u4fe1\u7684\u6838\u5fc3\u539f\u56e0\u3002\n\n```\n\u5dee\u5206\u4fe1\u53f7\u539f\u7406\u793a\u610f:\n\n\u53d1\u9001\u7aef         \u4f20\u8f93\u7ebf         \u63a5\u6536\u7aef\n  A \u2500\u2500\u2500\u2500\u2192 \u6ce2\u5f62: \u2500\u2500\u2500\u2572___\u2571\u2500\u2500\u2500 \u2192 A\n                        \u2193 \n              \u5dee\u503c = (VA - VB) = \u903b\u8f91\u5224\u5b9a\u4f9d\u636e\n                        \u2191\n  B \u2500\u2500\u2500\u2500\u2192 \u6ce2\u5f62: ___\u2571\u203e\u203e\u203e\u2572___ \u2192 B\n\n\u566a\u58f0\u540c\u65f6\u53e0\u52a0\u5728 A \u548c B \u4e0a \u2192 \u76f8\u51cf\u540e\u566a\u58f0\u88ab\u6d88\u9664\n```\n\n### 1.2 RS-485 \u7535\u6c14\u53c2\u6570\u901f\u67e5\n\n![\u7ec8\u7aef\u7535\u963b\u4f5c\u7528\u539f\u7406](https:\/\/www.modbus.cn\/wp-content\/uploads\/diagrams\/a04-termination-resistor.svg)\u25b2 \u56fe2\uff1a\u7ec8\u7aef\u7535\u963b\u6d88\u9664\u4fe1\u53f7\u53cd\u5c04\u7684\u539f\u7406 \u2014 \u6709\/\u65e0\u7ec8\u7aef\u7535\u963b\u7684\u4fe1\u53f7\u6ce2\u5f62\u5bf9\u6bd4\u3002\n\n    \n        \u53c2\u6570\u5178\u578b\u503c\u8bf4\u660e\n    \n    \n        \u5dee\u5206\u8f93\u51fa\u7535\u538b\uff08\u5e26\u8f7d\uff09\u2265 1.5V\u63a5 54\u03a9 \u8d1f\u8f7d\u65f6\n        \u5dee\u5206\u8f93\u51fa\u7535\u538b\uff08\u7a7a\u8f7d\uff09\u2264 5V\n        \u63a5\u6536\u5668\u8f93\u5165\u7075\u654f\u5ea6\u00b1200mV\u6700\u5c0f\u53ef\u8bc6\u522b\u7684\u5dee\u5206\u7535\u538b\n        \u5171\u6a21\u7535\u538b\u8303\u56f4-7V ~ +12VA\/B \u5bf9\u5730\u7684\u6700\u5927\u7535\u538b\u8303\u56f4\n        \u77ed\u8def\u7535\u6d41\u2264 250mAA\/B \u77ed\u8def\u65f6\u7684\u6700\u5927\u7535\u6d41\n        \u7279\u6027\u963b\u6297120\u03a9\u6807\u51c6\u53cc\u7ede\u7ebf\u7684\u7279\u6027\u963b\u6297\n    \n\n## \u4e8c\u3001\u63a5\u7ebf\u5b9e\u6218\uff1a\u83ca\u82b1\u94fe vs \u661f\u578b\u62d3\u6251\n\n### 2.1 \u83ca\u82b1\u94fe\u62d3\u6251\uff08\u6b63\u786e\u505a\u6cd5\uff09\n\n\u83ca\u82b1\u94fe\uff08Daisy Chain\uff09\u662f RS-485 \u552f\u4e00\u63a8\u8350\u7684\u62d3\u6251\u7ed3\u6784\u3002\u6240\u6709\u8bbe\u5907\u4e32\u8054\u5728\u4e00\u6761\u603b\u7ebf\u4e0a\uff0c\u6ca1\u6709\u4efb\u4f55\u5206\u652f\uff1a\n\n```\n\u6b63\u786e \u2705 \u83ca\u82b1\u94fe\u62d3\u6251:\n\n \u4e3b\u7ad9 \u2500\u2500\u2500 \u4ece\u7ad91 \u2500\u2500\u2500 \u4ece\u7ad92 \u2500\u2500\u2500 \u4ece\u7ad93 \u2500\u2500\u2500 \u7ec8\u7aef\u7535\u963b\n  \u2502         \u2502         \u2502         \u2502\n  \u2514\u2500A\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500A\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500A\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500A\n  \u2514\u2500B\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500B\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500B\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500B\n\n\u6bcf\u6bb5\u652f\u7ebf\u957f\u5ea6 \u2264 30cm\uff08\u8d8a\u77ed\u8d8a\u597d\uff09\n```\n\n### 2.2 \u661f\u578b\u62d3\u6251\uff08\u5e38\u89c1\u9519\u8bef\uff09\n\n\u5728\u7535\u5de5\u73b0\u573a\uff0c\u51fa\u4e8e\u8d70\u7ebf\u65b9\u4fbf\uff0c\u5f88\u591a\u4eba\u4f1a\u4e0d\u81ea\u89c9\u5730\u628a RS-485 \u63a5\u6210\u661f\u578b\uff1a\n\n```\n\u9519\u8bef \u274c \u661f\u578b\u62d3\u6251:\n\n         \u250c\u2500\u2500\u2500\u2500 \u4ece\u7ad91\n         \u2502\n \u4e3b\u7ad9 \u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500 \u4ece\u7ad92\n         \u2502\n         \u2514\u2500\u2500\u2500\u2500 \u4ece\u7ad93\n\n\u95ee\u9898\uff1a\u6bcf\u6761\u5206\u652f\u7684\u963b\u6297\u4e0d\u8fde\u7eed\uff0c\u4fe1\u53f7\u5728\u5206\u53c9\u5904\u4ea7\u751f\u4e25\u91cd\u53cd\u5c04\n```\n\n**\u661f\u578b\u62d3\u6251\u7684\u540e\u679c\uff1a**\n\n    - \u4fe1\u53f7\u53cd\u5c04\u4e25\u91cd\uff0c\u5bfc\u81f4\u901a\u4fe1\u65f6\u597d\u65f6\u574f\n    - \u4f4e\u6ce2\u7279\u7387\uff08\u22649600bps\uff09\u65f6\u53ef\u80fd\u52c9\u5f3a\u5de5\u4f5c\uff0c\u5347\u9ad8\u540e\u7acb\u523b\u5d29\u6e83\n    - \u67d0\u4e9b\u8bbe\u5907\u901a\u4fe1\u6b63\u5e38\uff0c\u53e6\u4e00\u4e9b\u5b8c\u5168\u4e0d\u54cd\u5e94\n\n**\u5982\u679c\u73b0\u573a\u5df2\u7ecf\u5e03\u6210\u661f\u578b\u600e\u4e48\u529e\uff1f**\n\n    - \u4f7f\u7528 RS-485 \u96c6\u7ebf\u5668\uff08HUB\uff09\u2014\u2014\u5c06\u661f\u578b\u62d3\u6251\u7684\u5404\u4e2a\u5206\u652f\u7535\u6c14\u9694\u79bb\n    - \u4f7f\u7528 RS-485 \u4e2d\u7ee7\u5668\u2014\u2014\u5c06\u4e00\u6761\u603b\u7ebf\u62c6\u5206\u4e3a\u591a\u4e2a\u72ec\u7acb\u7684\u603b\u7ebf\u6bb5\n    - \u91cd\u65b0\u5e03\u7ebf\uff08\u6700\u5f7b\u5e95\u4f46\u6210\u672c\u6700\u9ad8\uff09\n\n### 2.3 A\/B \u7ebf\u7684\u6b63\u786e\u63a5\u6cd5\n\n**\u884c\u4e1a\u6700\u5927\u7684\u75db\u70b9\uff1aA\/B \u7ebf\u6807\u8bc6\u4e0d\u7edf\u4e00\uff01**\n\n\u4e0d\u540c\u5382\u5546\u5bf9 RS-485 \u7684 A\/B \u7ebf\u6807\u8bc6\u65b9\u5f0f\u5404\u4e0d\u76f8\u540c\uff0c\u6709\u4e9b\u751a\u81f3\u5b8c\u5168\u76f8\u53cd\u3002\u4ee5\u4e0b\u662f\u5e38\u89c1\u7684\u6807\u8bc6\u65b9\u5f0f\u5bf9\u7167\u8868\uff1a\n\n    \n        \u5382\u5546\u6807\u8bc6\u65b9\u5f0f\u7a7a\u95f2\u72b6\u6001\u9ad8\u7535\u5e73\u7684\u7ebf\n    \n    \n        \u5927\u591a\u6570\u56fd\u4ea7\u8bbe\u5907A \/ BA\n        \u65bd\u8010\u5fb7\u3001\u897f\u95e8\u5b50D1 \/ D0D1\n        \u90e8\u5206\u8fdb\u53e3\u8bbe\u5907+ \/ -+\n        \u67d0\u4e9b\u7279\u6b8a\u8bbe\u5907A \u6807\u8bb0\u4e3a\u8d1f\uff08-\uff09\u7aefB\uff01\uff08\u4e0e\u5927\u591a\u6570\u76f8\u53cd\uff09\n    \n\n**\u4e07\u80fd\u9a8c\u8bc1\u65b9\u6cd5\uff1a**\u7528\u4e07\u7528\u8868\u6d4b\u91cf\u8bbe\u5907\u5728\u7a7a\u95f2\u72b6\u6001\u4e0b\u7684 A\/B \u4e4b\u95f4\u7535\u538b\u3002\u5982\u679c A \u5bf9 B \u4e3a\u6b63\uff08\u7ea6 +0.2V ~ +5V\uff09\uff0c\u5219\u4e24\u6839\u7ebf\u90fd\u63a5\u5bf9\u4e86\uff08\u540c\u6807\u8bc6\u4e92\u8fde\uff09\u3002\u5982\u679c\u8bfb\u6570\u4e3a\u8d1f\uff0c\u5219\u67d0\u53f0\u8bbe\u5907\u7684 A\/B \u6807\u8bc6\u53cd\u8f6c\u4e86\u3002\n\n## \u4e09\u3001\u7ec8\u7aef\u7535\u963b\uff1a\u4e3a\u4ec0\u4e48\u9700\u8981\u5b83\uff0c\u600e\u4e48\u9009\n\n### 3.1 \u4fe1\u53f7\u53cd\u5c04\u7684\u7269\u7406\u539f\u7406\n\n\u5f53\u7535\u4fe1\u53f7\u6cbf\u4f20\u8f93\u7ebf\u4f20\u64ad\u5230\u672b\u7aef\u65f6\uff0c\u5982\u679c\u672b\u7aef\u963b\u6297\u4e0e\u4f20\u8f93\u7ebf\u7684\u7279\u6027\u963b\u6297\u4e0d\u5339\u914d\uff0c\u4e00\u90e8\u5206\u4fe1\u53f7\u80fd\u91cf\u4f1a\u53cd\u5c04\u56de\u6765\uff0c\u53e0\u52a0\u5728\u539f\u59cb\u4fe1\u53f7\u4e0a\u3002\u53cd\u5c04\u4fe1\u53f7\u4f1a\u5bfc\u81f4\u6ce2\u5f62\u7578\u53d8\uff0c\u4e25\u91cd\u65f6\u63a5\u6536\u7aef\u65e0\u6cd5\u6b63\u786e\u8bc6\u522b\u903b\u8f91\u7535\u5e73\u3002\n\n**\u7ec8\u7aef\u7535\u963b\u7684\u4f5c\u7528\uff1a**\u5728\u603b\u7ebf\u4e24\u7aef\u5404\u5e76\u8054\u4e00\u4e2a\u7b49\u4e8e\u7279\u6027\u963b\u6297\u7684\u7535\u963b\uff08120\u03a9\uff09\uff0c\u5438\u6536\u5230\u8fbe\u672b\u7aef\u7684\u4fe1\u53f7\u80fd\u91cf\uff0c\u6d88\u9664\u53cd\u5c04\u3002\n\n### 3.2 \u7ec8\u7aef\u7535\u963b\u914d\u7f6e\u89c4\u5219\n\n    \n        \u573a\u666f\u7ec8\u7aef\u7535\u963b\u914d\u7f6e\n    \n    \n        \u77ed\u8ddd\u79bb\uff08\uff1c50m\uff09\u3001\u4f4e\u901f\u7387\uff08\u22649600bps\uff09\u53ef\u4e0d\u52a0\u7ec8\u7aef\u7535\u963b\uff08\u5b9e\u8df5\u4e2d\u4ecd\u5efa\u8bae\u52a0\uff09\n        \u4e2d\u7b49\u8ddd\u79bb\uff0850m~300m\uff09\u603b\u7ebf\u4e24\u7aef\u5404\u52a0 120\u03a9\n        \u957f\u8ddd\u79bb\uff08\uff1e300m\uff09\u6216\u9ad8\u901f\u7387\uff08\uff1e19200bps\uff09\u603b\u7ebf\u4e24\u7aef\u5404\u52a0 120\u03a9 + \u504f\u7f6e\u7535\u963b\n        \u4e3b\u7ad9\u4f4d\u4e8e\u603b\u7ebf\u4e2d\u95f4\u603b\u7ebf\u4e24\u7aef\u5404\u52a0 120\u03a9\uff08\u4e3b\u7ad9\u672c\u8eab\u4e0d\u52a0\uff09\n    \n\n**\u91cd\u8981\uff1a**\u7ec8\u7aef\u7535\u963b\u53ea\u9700\u5728\u603b\u7ebf\u7684\u6700\u8fdc\u4e24\u7aef\u6dfb\u52a0\uff0c\u5207\u52ff\u5728\u4e2d\u95f4\u7684\u6bcf\u4e2a\u8282\u70b9\u90fd\u6dfb\u52a0\uff01\u591a\u52a0\u7ec8\u7aef\u7535\u963b\u4f1a\u5bfc\u81f4\u603b\u7ebf\u8d1f\u8f7d\u8fc7\u91cd\uff0c\u4fe1\u53f7\u5e45\u5ea6\u4e25\u91cd\u964d\u4f4e\u3002\n\n### 3.3 \u7528\u4e07\u7528\u8868\u9a8c\u8bc1\u7ec8\u7aef\u7535\u963b\n\n\u65ad\u5f00\u6240\u6709\u8bbe\u5907\u7535\u6e90\uff0c\u7528\u4e07\u7528\u8868\u6d4b\u91cf A \u548c B \u4e4b\u95f4\u7684\u7535\u963b\uff1a\n\n    - \u5982\u679c\u4e24\u7aef\u5404\u6709\u4e00\u4e2a 120\u03a9 \u7ec8\u7aef\u7535\u963b \u2192 \u6d4b\u91cf\u503c\u5e94\u7ea6\u4e3a 60\u03a9\uff08\u4e24\u4e2a 120\u03a9 \u5e76\u8054\uff09\n    - \u5982\u679c\u6ca1\u6709\u7ec8\u7aef\u7535\u963b \u2192 \u6d4b\u91cf\u503c\u5e94\u4e3a\u9ad8\u963b\uff08\uff1e1k\u03a9\uff09\n    - \u5982\u679c\u53ea\u6709\u4e00\u4e2a\u7ec8\u7aef\u7535\u963b \u2192 \u6d4b\u91cf\u503c\u5e94\u7ea6\u4e3a 120\u03a9\n\n## \u56db\u3001\u504f\u7f6e\u7535\u963b\uff1a\u9632\u6b62\u603b\u7ebf\u300c\u60ac\u7a7a\u300d\n\n### 4.1 \u4e3a\u4ec0\u4e48\u8981\u504f\u7f6e\uff1f\n\n\u5f53\u603b\u7ebf\u4e0a\u6240\u6709\u8bbe\u5907\u90fd\u5904\u4e8e\u63a5\u6536\u72b6\u6001\uff08\u5373\u6ca1\u6709\u8bbe\u5907\u5728\u53d1\u9001\uff09\u65f6\uff0cA \u548c B \u4e4b\u95f4\u7684\u5dee\u5206\u7535\u538b\u63a5\u8fd1 0V\u3002\u5bf9\u4e8e\u7075\u654f\u5ea6\u4e3a \u00b1200mV \u7684 RS-485 \u63a5\u6536\u5668\u6765\u8bf4\uff0c\u8fd9\u4e2a\u6a21\u7cca\u7684\u72b6\u6001\u53ef\u80fd\u5bfc\u81f4\uff1a\n\n    - \u63a5\u6536\u5668\u8f93\u51fa\u968f\u673a\u7ffb\u8f6c\uff0c\u4ea7\u751f\u300c\u5047\u6570\u636e\u300d\n    - \u4ece\u7ad9\u7684 UART \u6536\u5230\u5927\u91cf\u5783\u573e\u5b57\u8282\uff0c\u5bfc\u81f4\u5e27\u9519\u8bef\n    - \u901a\u4fe1\u6307\u793a\u706f\u65e0\u89c4\u5f8b\u95ea\u70c1\n\n\u504f\u7f6e\u7535\u963b\uff08Fail-Safe Bias\uff09\u901a\u8fc7\u5728 A \u548c B \u7ebf\u4e0a\u65bd\u52a0\u4e00\u4e2a\u786e\u5b9a\u7684\u504f\u7f6e\u7535\u538b\uff0c\u786e\u4fdd\u603b\u7ebf\u5728\u7a7a\u95f2\u72b6\u6001\u4e0b\u4fdd\u6301\u786e\u5b9a\u7684\u903b\u8f91 1 \u72b6\u6001\u3002\n\n### 4.2 \u504f\u7f6e\u7535\u963b\u7684\u8ba1\u7b97\u65b9\u6cd5\n\n\u6807\u51c6\u7684\u504f\u7f6e\u7535\u8def\u5c06 A \u7ebf\u901a\u8fc7\u4e00\u4e2a\u7535\u963b\u4e0a\u62c9\u5230 VCC\uff08\u901a\u5e38 +5V\uff09\uff0c\u5c06 B \u7ebf\u901a\u8fc7\u4e00\u4e2a\u7b49\u503c\u7535\u963b\u4e0b\u62c9\u5230 GND\uff1a\n\n```\n\u504f\u7f6e\u7535\u8def\u793a\u610f\u56fe:\n\nVCC (+5V)\n  \u2502\n  \u251c\u2500\u2500 Rb \u2500\u2500\u252c\u2500\u2500 A \u7ebf \u2500\u2500\u2500\u2500 Rt(120\u03a9) \u2500\u2500\u2500\u2500 B \u7ebf \u2500\u2500\u252c\u2500\u2500 Rb \u2500\u2500\u2524\n           \u2502                                  \u2502\n        \u8bbe\u5907\u63a5\u53e3                              GND\n\nRb = \u504f\u7f6e\u7535\u963b, Rt = \u7ec8\u7aef\u7535\u963b\n```\n\n**\u504f\u7f6e\u7535\u963b\u503c\u7684\u9009\u62e9\uff1a**\n\n    - \u76ee\u6807\u504f\u7f6e\u7535\u538b \u2265 200mV\uff08\u63a5\u6536\u5668\u6700\u5c0f\u8bc6\u522b\u7535\u538b\uff09\n    - \u63a8\u8350\u504f\u7f6e\u7535\u538b 250mV ~ 300mV\uff0c\u7559\u6709\u4f59\u91cf\n    - \u5e38\u89c1\u914d\u7f6e\uff1a1 \u4e2a\u7ec8\u7aef\u7535\u963b + 2 \u4e2a 680\u03a9 \u504f\u7f6e\u7535\u963b\n    - \u5982\u679c\u4e24\u4e2a\u7ec8\u7aef\u7535\u963b\uff0860\u03a9 \u5e76\u8054\uff09\uff1a\u504f\u7f6e\u7535\u963b\u53d6 560\u03a9 ~ 680\u03a9\n\n**\u8ba1\u7b97\u516c\u5f0f\uff08\u4e24\u7aef\u90fd\u6709\u7ec8\u7aef\u7535\u963b\u65f6\uff09\uff1a**\n\n```\nVab = VCC \u00d7 Rt \/ (Rt + 2 \u00d7 Rb)\n\n\u5176\u4e2d:\n  VCC = 5V\uff08\u5178\u578b\u504f\u7f6e\u7535\u6e90\u7535\u538b\uff09\n  Rt  = 60\u03a9\uff08\u4e24\u4e2a 120\u03a9 \u7ec8\u7aef\u7535\u963b\u5e76\u8054\uff09\n  Vab \u2265 0.2V\uff08\u76ee\u6807\u504f\u7f6e\u7535\u538b\uff09\n\n\u89e3\u51fa: Rb \u2264 720\u03a9\n\n\u5b9e\u9645\u53d6\u6807\u51c6\u503c 560\u03a9 \u6216 680\u03a9\n```\n\n### 4.3 \u4f55\u65f6\u9700\u8981\u52a0\u504f\u7f6e\u7535\u963b\uff1f\n\n**\u5fc5\u987b\u52a0\u504f\u7f6e\u7535\u963b\u7684\u573a\u666f\uff1a**\n\n    - \u603b\u7ebf\u5df2\u5b89\u88c5\u7ec8\u7aef\u7535\u963b\uff08\u7ec8\u7aef\u7535\u963b\u4f1a\u4f7f\u7a7a\u95f2\u7535\u538b\u8d8b\u8fd1\u4e8e\u96f6\uff09\n    - \u603b\u7ebf\u4e0a\u8bbe\u5907\u6570\u91cf\u8f83\u591a\uff08\uff1e10 \u4e2a\uff09\uff0c\u63a5\u6536\u5668\u6f0f\u7535\u6d41\u7d2f\u79ef\u5f71\u54cd\u504f\u7f6e\n    - \u957f\u8ddd\u79bb\u901a\u4fe1\uff08\uff1e300m\uff09\uff0c\u566a\u58f0\u5bb9\u9650\u964d\u4f4e\n\n**\u53ef\u4ee5\u4e0d\u5b89\u88c5\u504f\u7f6e\u7535\u963b\u7684\u573a\u666f\uff1a**\n\n    - \u6ca1\u6709\u5b89\u88c5\u7ec8\u7aef\u7535\u963b\uff08\u8bbe\u5907\u5185\u90e8\u901a\u5e38\u5df2\u6709\u5f31\u504f\u7f6e\uff09\n    - \u603b\u7ebf\u4e0a\u5927\u90e8\u5206\u8bbe\u5907\u81ea\u8eab\u5df2\u7ecf\u5185\u7f6e\u4e86\u504f\u7f6e\u529f\u80fd\n\n## \u4e94\u3001\u63a5\u5730\uff1a\u88ab\u5ffd\u89c6\u7684\u5173\u952e\u73af\u8282\n\nRS-485 \u662f\u5dee\u5206\u4fe1\u53f7\uff0c\u7406\u8bba\u4e0a\u4e0d\u9700\u8981\u516c\u5171\u5730\u7ebf\u3002\u4f46\u5728\u5b9e\u9645\u5de5\u7a0b\u4e2d\uff0c\u63a5\u5730\u95ee\u9898\u4ecd\u7136\u662f\u5bfc\u81f4\u901a\u4fe1\u4e0d\u7a33\u5b9a\u7684\u7b2c\u4e09\u5927\u539f\u56e0\uff08\u4ec5\u6b21\u4e8e\u63a5\u7ebf\u9519\u8bef\u548c\u7ec8\u7aef\u7535\u963b\u95ee\u9898\uff09\u3002\n\n### 5.1 \u5171\u6a21\u7535\u538b\u8d8a\u9650\n\n\u5f53\u4e24\u4e2a\u8bbe\u5907\u7684\u300c\u5730\u300d\u4e4b\u95f4\u5b58\u5728\u8f83\u5927\u7684\u7535\u4f4d\u5dee\u65f6\uff0cA \u7ebf\u548c B \u7ebf\u76f8\u5bf9\u4e8e\u63a5\u6536\u7aef\u5730\u7684\u7535\u538b\u53ef\u80fd\u8d85\u51fa RS-485 \u6536\u53d1\u5668\u7684\u5171\u6a21\u8303\u56f4\uff08-7V ~ +12V\uff09\uff0c\u5bfc\u81f4\u6536\u53d1\u5668\u635f\u574f\u6216\u5de5\u4f5c\u5f02\u5e38\u3002\u8fd9\u5c31\u662f\u4e3a\u4ec0\u4e48\u5373\u4f7f\u662f\u5dee\u5206\u4fe1\u53f7\uff0c\u4ecd\u5efa\u8bae\u4f7f\u7528\u4fe1\u53f7\u5730\u7ebf\uff08SG\uff09\u8fde\u63a5\u6240\u6709\u8bbe\u5907\u7684\u516c\u5171\u7aef\u3002\n\n**\u63a5\u5730\u5efa\u8bae\uff1a**\n\n    - \u5c3d\u91cf\u4f7f\u7528\u5e26\u5c4f\u853d\u5c42\u7684\u53cc\u7ede\u7ebf\uff08\u5982 Belden 3105A\uff09\n    - \u5c4f\u853d\u5c42\u5355\u70b9\u63a5\u5730\uff08\u901a\u5e38\u5728\u4e3b\u7ad9\u7aef\uff09\uff0c\u907f\u514d\u5730\u73af\u8def\n    - \u5982\u679c\u6709\u7b2c\u4e09\u6839\u7ebf\u7528\u4f5c\u4fe1\u53f7\u5730\uff08SG\uff09\uff0c\u5728\u6bcf\u53f0\u8bbe\u5907\u5904\u901a\u8fc7 100\u03a9 \u7535\u963b\u8fde\u63a5\u5230\u672c\u5730\u5730\n\n### 5.2 \u9694\u79bb\u7684\u91cd\u8981\u6027\n\n\u5728\u5de5\u4e1a\u73b0\u573a\uff0c\u5f3a\u70c8\u5efa\u8bae\u4f7f\u7528\u5e26\u5149\u7535\u9694\u79bb\u6216\u78c1\u9694\u79bb\u7684 RS-485 \u63a5\u53e3\u3002\u9694\u79bb\u53ef\u4ee5\uff1a\n\n    - \u6d88\u9664\u5730\u7535\u4f4d\u5dee\u5bfc\u81f4\u7684\u5171\u6a21\u7535\u538b\u95ee\u9898\n    - \u9632\u6b62\u96f7\u51fb\u548c\u6d6a\u6d8c\u901a\u8fc7\u901a\u4fe1\u7ebf\u8def\u635f\u574f\u8bbe\u5907\n    - \u963b\u65ad\u63a5\u5730\u73af\u8def\u5f15\u8d77\u7684 50Hz \u5de5\u9891\u5e72\u6270\n\n## \u516d\u3001\u7ebf\u7f06\u9009\u62e9\u6307\u5357\n\n    \n        \u53c2\u6570\u63a8\u8350\u503c\u8bf4\u660e\n    \n    \n        \u7ebf\u7f06\u7c7b\u578b\u7279\u6027\u963b\u6297 120\u03a9 \u7684\u53cc\u7ede\u5c4f\u853d\u7ebf\u5982 Belden 3105A\u30019841\n        \u7ebf\u5f8424AWG\uff080.2mm\u00b2\uff09\u6216\u66f4\u7c97\u957f\u8ddd\u79bb\u65f6\u9009\u66f4\u7c97\u7684\u7ebf\u5f84\n        \u5c4f\u853d\u5c42\u94dd\u7b94 + \u7f16\u7ec7\u7f51\u53cc\u91cd\u5c4f\u853d\u5f3a\u5e72\u6270\u73af\u5883\u5fc5\u5907\n        \u5bf9\u6570\u81f3\u5c11 1 \u5bf9\uff08A\/B\uff09+ 1 \u6839\u5730\u7ebf\u63a8\u8350 1.5 \u5bf9\u6216 2 \u5bf9\n        \u63a8\u8350\u54c1\u724cBelden\u3001LAPP\u3001Nexans\u56fd\u4ea7\uff1a\u4ea8\u901a\u3001\u4e2d\u5929\n    \n\n**\u5343\u4e07\u4e0d\u8981\u7528\u7684\u7ebf\uff1a**\n\n    - \u666e\u901a\u5e73\u884c\u7ebf\uff08\u975e\u53cc\u7ede\uff09\u2014\u2014\u6ca1\u6709\u963b\u6297\u63a7\u5236\uff0c\u4fe1\u53f7\u8d28\u91cf\u6781\u5dee\n    - \u7f51\u7ebf\u4e2d\u7684\u4e00\u5bf9\uff08100\u03a9 \u7279\u6027\u963b\u6297\uff09\u2014\u2014\u4e0e 120\u03a9 \u4e0d\u5b8c\u5168\u5339\u914d\uff0c\u957f\u8ddd\u79bb\u4e0d\u53ef\u9760\n    - \u7535\u529b\u7535\u7f06\u2014\u2014\u5f3a\u7535\u5e72\u6270\u4e25\u91cd\uff0c\u4e14\u5b89\u5168\u6027\u4e0d\u5141\u8bb8\n\n## \u4e03\u3001\u8c03\u8bd5\u5de5\u5177\u4e0e\u6545\u969c\u6392\u67e5 SOP\n\n### 7.1 \u5fc5\u5907\u8c03\u8bd5\u5de5\u5177\n\n    \n        \u5de5\u5177\u7528\u9014\u63a8\u8350\u578b\u53f7\n    \n    \n        \u4e07\u7528\u8868\u6d4b\u7535\u538b\u3001\u7535\u963b\u3001\u901a\u65adFluke 17B+\n        USB \u8f6c RS-485\u8fde\u63a5\u7535\u8111\u8c03\u8bd5FTDI \u82af\u7247\u65b9\u6848\uff08\u5982 UT-890A\uff09\n        Modbus \u8c03\u8bd5\u8f6f\u4ef6\u6536\u53d1 Modbus \u62a5\u6587Modbus Poll\u3001QModMaster\n        \u793a\u6ce2\u5668\uff08\u53ef\u9009\uff09\u89c2\u5bdf\u4fe1\u53f7\u6ce2\u5f62\u3001\u53cd\u5c04Rigol DS1054Z\n        RS-485 \u6d4b\u8bd5\u4eea\u4e13\u7528\u603b\u7ebf\u5206\u6790Witte 485-Tester\n    \n\n### 7.2 \u6545\u969c\u6392\u67e5 SOP\uff08\u6807\u51c6\u64cd\u4f5c\u6d41\u7a0b\uff09\n\n\u5f53 Modbus RTU \u901a\u4fe1\u51fa\u73b0\u95ee\u9898\u65f6\uff0c\u8bf7\u6309\u4ee5\u4e0b\u987a\u5e8f\u6392\u67e5\uff1a\n\n    - **\u65ad\u7535\uff0c\u6d4b\u7535\u963b\uff1a**\u7528\u4e07\u7528\u8868\u6d4b A-B \u95f4\u7535\u963b \u2248 60\u03a9\uff08\u6709\u7ec8\u7aef\u7535\u963b\uff09\u6216\u9ad8\u963b\uff08\u65e0\u7ec8\u7aef\u7535\u963b\uff09\n    - **\u4e0a\u7535\uff0c\u6d4b\u7535\u538b\uff1a**\u7a7a\u95f2\u72b6\u6001\u4e0b\uff0cA \u5bf9 GND \u5e94 \uff1e B \u5bf9 GND\uff08\u7a7a\u95f2\u72b6\u6001\u4e3a\u903b\u8f91 1\uff09\n    - **\u68c0\u67e5\u62d3\u6251\uff1a**\u786e\u8ba4\u662f\u83ca\u82b1\u94fe\uff0c\u65e0\u661f\u578b\u5206\u652f\n    - **\u5355\u8bbe\u5907\u6d4b\u8bd5\uff1a**\u53ea\u8fde\u63a5\u4e00\u4e2a\u4ece\u7ad9\uff08\u52a0\u7ec8\u7aef\u7535\u963b\uff09\uff0c\u7528 Modbus Poll \u6d4b\u8bd5\n    - **\u9010\u4e00\u6dfb\u52a0\uff1a**\u6bcf\u6b21\u589e\u52a0\u4e00\u4e2a\u4ece\u7ad9\uff0c\u786e\u8ba4\u901a\u4fe1\u6b63\u5e38\u540e\u518d\u52a0\u4e0b\u4e00\u4e2a\n    - **\u6ce2\u7279\u7387\u626b\u63cf\uff1a**\u5982\u679c\u4e0d\u786e\u5b9a\u8bbe\u5907\u6ce2\u7279\u7387\uff0c\u4ece 9600 \u5f00\u59cb\u9010\u7ea7\u5c1d\u8bd5\n\n## \u516b\u3001\u5e38\u89c1\u95ee\u9898 FAQ\n\n### Q1: \u7ec8\u7aef\u7535\u963b\u5fc5\u987b\u7cbe\u786e 120\u03a9 \u5417\uff1f\n\n\u4e0d\u9700\u8981\u7cbe\u786e\u5339\u914d\u3002\u4f7f\u7528 120\u03a9 \u00b1 5%\uff08114~126\u03a9\uff09\u5373\u53ef\u30021\/4W \u529f\u7387\u8db3\u591f\u3002\u5173\u952e\u662f\u8981\u52a0\uff0c\u800c\u4e0d\u662f\u7cbe\u786e\u5230\u591a\u5c11\u6b27\u59c6\u3002\n\n### Q2: \u52a0\u7ec8\u7aef\u7535\u963b\u540e\u901a\u4fe1\u53cd\u800c\u53d8\u5dee\u600e\u4e48\u529e\uff1f\n\n\u8fd9\u53ef\u80fd\u662f\u56e0\u4e3a\u52a0\u4e86\u7ec8\u7aef\u7535\u963b\u4f46\u6ca1\u6709\u52a0\u504f\u7f6e\u7535\u963b\u3002\u7ec8\u7aef\u7535\u963b\u5c06\u7a7a\u95f2\u7535\u538b\u62c9\u4f4e\u5230\u4e86\u63a5\u6536\u5668\u7684\u6a21\u7cca\u533a\u3002\u89e3\u51b3\u65b9\u6cd5\u662f\u540c\u65f6\u5b89\u88c5\u504f\u7f6e\u7535\u963b\uff08\u5982 2 \u00d7 680\u03a9\uff09\u3002\n\n### Q3: \u6bcf\u4e2a\u8bbe\u5907\u7684\u652f\u7ebf\u6700\u957f\u53ef\u4ee5\u591a\u957f\uff1f\n\n\u7406\u8bba\u4e0a\uff0c\u652f\u7ebf\u957f\u5ea6\u5e94\u6ee1\u8db3\uff1a\u652f\u7ebf\u5ef6\u8fdf \uff1c \u4fe1\u53f7\u4e0a\u5347\u65f6\u95f4\u7684 1\/4\u3002\u5bf9\u4e8e\u5178\u578b\u7684 RS-485 \u9a71\u52a8\u5668\uff08\u4e0a\u5347\u65f6\u95f4\u7ea6 100ns\uff09\uff0c\u652f\u7ebf\u957f\u5ea6\u5e94 \u2264 5 \u7c73\u3002\u4f46\u5728\u5b9e\u8df5\u4e2d\uff0c\u5efa\u8bae\u5c06\u652f\u7ebf\u63a7\u5236\u5728 30 \u5398\u7c73\u4ee5\u5185\u3002\n\n### Q4: \u8bbe\u5907\u7a7a\u95f2\u65f6\u901a\u4fe1\u706f\u95ea\u70c1\u662f\u6b63\u5e38\u7684\u5417\uff1f\n\n\u4e0d\u6b63\u5e38\u3002\u7a7a\u95f2\u65f6\u5982\u679c\u901a\u4fe1\u6307\u793a\u706f\u95ea\u70c1\uff0c\u8bf4\u660e\u63a5\u6536\u5668\u5728\u8f93\u51fa\u968f\u673a\u6570\u636e\u3002\u8fd9\u901a\u5e38\u662f\u56e0\u4e3a\u7f3a\u5c11\u504f\u7f6e\u7535\u963b\u5bfc\u81f4\u603b\u7ebf\u72b6\u6001\u4e0d\u786e\u5b9a\u3002\u5b89\u88c5\u504f\u7f6e\u7535\u963b\u5373\u53ef\u89e3\u51b3\u3002\n\n## \u4e5d\u3001\u603b\u7ed3\n\nRS-485 \u5e03\u7ebf\u662f Modbus \u901a\u4fe1\u53ef\u9760\u6027\u7684\u57fa\u77f3\u3002\u8bb0\u4f4f\u8fd9\u4e09\u6761\u9ec4\u91d1\u6cd5\u5219\uff0c\u53ef\u4ee5\u907f\u514d\u7edd\u5927\u591a\u6570\u73b0\u573a\u95ee\u9898\uff1a\n\n    - **\u53ea\u7528\u83ca\u82b1\u94fe\u62d3\u6251**\u2014\u2014\u4e0d\u8981\u51fa\u73b0\u4efb\u4f55\u5206\u652f\n    - **\u4e24\u7aef\u63a5\u7ec8\u7aef\u7535\u963b\uff08120\u03a9\uff09\uff0c\u4e00\u5904\u52a0\u504f\u7f6e\u7535\u963b\uff082 \u00d7 680\u03a9\uff09**\u2014\u2014\u4e24\u8005\u7f3a\u4e00\u4e0d\u53ef\n    - **A \u8fde A\uff0cB \u8fde B**\u2014\u2014\u4e0a\u7535\u540e\u7528\u4e07\u7528\u8868\u9a8c\u8bc1 A \u5bf9 B \u7684\u7535\u538b\u4e3a\u6b63\n\n\u5f53\u4f60\u628a\u8fd9\u4e9b\u7535\u6c14\u5c42\u9762\u7684\u95ee\u9898\u4e00\u4e00\u6392\u9664\u540e\uff0c\u518d\u53bb\u770b\u534f\u8bae\u62a5\u6587\uff0c\u4f60\u4f1a\u53d1\u73b0\u2014\u2014\u539f\u6765 Modbus \u901a\u4fe1\u53ef\u4ee5\u5982\u6b64\u7a33\u5b9a\u3002\n\n**\u76f8\u5173\u9605\u8bfb\uff1a**Modbus RTU \u4e0e TCP \u6df1\u5ea6\u5bf9\u6bd4 | Modbus \u5f02\u5e38\u54cd\u5e94\u7801\u5b8c\u5168\u624b\u518c | Modbus CRC \u6821\u9a8c\u539f\u7406\u4e0e\u7f16\u7a0b\u5b9e\u73b0\n\n---\n*modbus.cn*\n"