InLine Null Modem Adapter DB9 Pin Plug / Socket

The InLine Null Modem Adapter DB9 Pin male / female is an inline serial adapter that connects to an existing serial cable and enables point-to-point serial data transmission between two PCs or other RS‑232 devices. It provides a 9‑pin Sub D female connector on one side and a 9‑pin Sub D male plug on the other, with a crosswired pin assignment to implement null‑modem functionality.

Advantages

This adapter implements the required pin crossover in a compact in‑line form factor, requiring no additional wiring or configuration. It is compatible with standard DB9 serial cables and devices, is lightweight and easy to carry, and preserves the typical metal-shell DB9 mechanical connection for reliable contact.

Suitable for

• Direct serial communication between two computers (PC to PC)
• Connecting serial devices such as printers, measurement instruments, or legacy equipment that require null‑modem wiring
• Field or workshop use where a quick null‑modem connection is needed without rewiring

Key specifications

• Connector 1: 9‑pin Sub D female (DB9 female)
• Connector 2: 9‑pin Sub D male (DB9 male)
• Pin assignment (female -> male): 1+6 → 4, 2 → 3, 3 → 2, 4 → 6+1, 5 → 5, 7 → 8, 8 → 7, S → S, pin 9 not connected
• Colour: Silver
• Manufacturer: InLine, MPN: 31437, EAN: 4043718084524

How to use

Attach the adapter inline to an existing DB9 serial cable by connecting the DB9 male or female ends as required so that the adapter sits between the two cable ends or between a cable and a device. Once connected, establish a serial connection between the two devices using appropriate serial settings (baud rate, parity, data bits, stop bits) in the host software or terminal emulator. No additional configuration of the adapter is necessary.

Recommendations

Verify pinout compatibility with your devices before use and ensure serial communication parameters match on both ends. Do not rely on pin 9, as it is not connected on this adapter; if your equipment requires ring indicators or hardware flow control using that pin, use a different adapter or wiring solution.