{"id":10218,"date":"2025-07-01T14:09:00","date_gmt":"2025-07-01T06:09:00","guid":{"rendered":"https:\/\/totcables.com\/?p=10218"},"modified":"2025-07-01T14:09:00","modified_gmt":"2025-07-01T06:09:00","slug":"what-is-a-null-serial-cable-uses-pinout-and-how-it-works","status":"publish","type":"post","link":"https:\/\/totcables.com\/?p=10218","title":{"rendered":"What Is a Null Serial Cable? Uses, Pinout, and How It Works"},"content":{"rendered":"

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A null serial cable<\/strong>, also known as a null modem cable<\/strong>, is a type of RS-232 serial cable used to directly connect two devices (like two PCs) without a modem or intermediary hardware<\/strong>. Unlike a standard serial cable, a null modem cable swaps specific transmission and reception lines so that the devices can \u201ctalk\u201d to each other directly.<\/p>\n

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null serial cable

null serial cable<\/p><\/div>\\n<\/p>\n

In this guide, we\u2019ll explain what a null serial cable is, how it differs from standard serial cables, typical wiring (pinout), and where it\u2019s still used today.<\/p>\n

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What Is a Null Serial Cable?<\/h3>\n

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A null serial cable<\/strong> is a special type of DB9 or DB25 serial cable<\/strong> that crosses<\/strong> the transmit (TX) and receive (RX) signals between two devices. This allows both devices to communicate in a peer-to-peer fashion over the RS-232 standard, which is typically designed for device-to-host connections.<\/p>\n

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It is called ‘null modem’ because it eliminates the need for a modem<\/strong>, simulating modem functionality through internal wiring.<\/p>\n

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Null Serial Cable vs Standard Serial Cable<\/h3>\n

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Feature<\/th>\n

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Standard Serial Cable<\/th>\n

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Null Serial Cable<\/th>\n

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Purpose<\/td>\n

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Connect host to device<\/td>\n

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Connect two hosts (e.g., PC-PC)<\/td>\n

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Wiring<\/td>\n

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Pin-to-pin (1:1, 2:2…)<\/td>\n

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Crossover (TX-RX, RTS-CTS…)<\/td>\n

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Use Case<\/td>\n

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Modems, printers, serial devices<\/td>\n

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Direct device-to-device communication<\/td>\n

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Common Connectors<\/td>\n

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DB9, DB25<\/td>\n

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DB9, DB25<\/td>\n

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