DB9 Null Modem Male-Female RS-232 Adapter

This DB9 Null Modem male-female adapter allows a standard DB9 / D-SUB serial cable to be converted into a null modem connection by crossing the main RS-232 communication signals between two compatible devices.

In a straight serial cable, pins usually follow the same correspondence between connectors. In a null modem connection, transmit and receive lines are crossed, allowing direct communication between two serial devices such as computers, terminals, controllers, industrial equipment, configuration interfaces or devices requiring a crossed RS-232 connection.

The adapter has a DB9 male connector on one side and a DB9 female connector on the other, allowing it to be placed between the existing cable and the equipment without replacing the whole cable.

It is a practical solution for technicians, workshops, amateur radio operators, automation, legacy computing, equipment programming, device configuration and maintenance of systems using RS-232 serial ports.

Main features

DB9 Null Modem adapter
Connection type: DB9 / D-SUB
Connector A: DB9 male
Connector B: DB9 female
Main function: conversion of standard serial cable to null modem
Application: crossed RS-232 communication
Adapter type: passive
External power supply: not required
Installation: plug-and-play, no soldering required
Suitable for testing, maintenance and serial equipment configuration
Suitable for compatible DB9 cables and equipment
Not a USB to RS-232 converter
Not an RS-232 to TTL converter

Listed pinout

Pin 1: connected to pin 4
Pin 2: connected to pin 3
Pin 3: connected to pin 2
Pin 4: connected to pins 1 and 6
Pin 5: connected to pin 5
Pin 6: connected to pin 4
Pin 7: connected to pin 8
Pin 8: connected to pin 7
G / ground: connected to G / ground

Recommended applications

RS-232 communication between compatible devices
Converting a straight DB9 cable into a null modem cable
Industrial equipment configuration
Programming controllers and serial interfaces
Serial terminals
Automation equipment
Technical maintenance
Serial communication testing
Legacy computing and equipment with DB9 ports
Amateur radio and accessories with serial connection
Connecting two DTE devices when null modem wiring is required
Workshops, laboratories and service benches

Important note

Before use, always confirm the required pinout, equipment type, communication standard, serial speed, COM port settings, cable type and RS-232 compatibility.

This adapter only performs null modem conversion on a DB9 connection. It does not convert USB, TTL, RS-485, RS-422 or other protocols. For equipment using TTL levels, USB or different industrial interfaces, the appropriate converter must be used.

Serial communication may require correct baud rate, data bits, parity, stop bits and flow control settings in the software or equipment being used.