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Monoprice

Monoprice 101140 DB25 F/F Null Modem Adaptor

★★★★★5.0 (2 reviews)

A compact DB25 female-to-female null modem adapter for direct parallel port data transfers between devices.

$4.75*
✓ In Stock on Amazon.com
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*Price sourced from Amazon.com. Last updated:Jul 16, 2026.Price and availability are subject to change.

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Overview

The Monoprice 101140 DB25 Female-to-Female Null Modem Adapter is a simple but purpose-built piece of hardware for direct device-to-device communication through parallel ports. By crossing the transmission and receiving lines — the same principle behind crossover Ethernet cables — it eliminates the need for a modem or network infrastructure when you need to move data between two computers or devices equipped with DB25 parallel ports. The adapter is compact at just 2.8 by 2.4 by 0.8 inches and weighs a negligible 0.16 ounces, making it easy to toss in a toolbox or cable organizer.

This adapter serves a niche but important role for anyone maintaining legacy hardware, industrial equipment, or older computing systems that rely on parallel port communication. It is a passive device requiring no drivers or external power — you simply connect it between two male DB25 ports and use compatible file transfer software to initiate the data exchange. While parallel ports have largely disappeared from modern computers, the DB25 null modem adapter remains an essential tool for IT professionals, hobbyists, and technicians who work with vintage or specialized equipment where these connections are still standard.

Key Features

Parallel Connector (DB25) Null Modem Adapter

Null Modems have their transmission and receiving lines crossed like in a crossover cable to allow for direct device to device communications

Connect this between two parallel ports on a pair of computers for data link transfers

Additional software may be required

Specifications

Brand
Monoprice
Model
101140
Connector Type
DB25 Female to DB25 Female
Compatibility
Devices with DB25 parallel ports
Specific Use
Direct device-to-device data transfer
Dimensions
2.8 x 2.4 x 0.8 inches
Weight
0.16 ounces

Pros & Cons

👍 Pros

  • Extremely compact form factor takes up virtually no space and adds no cable bulk
  • Female-to-female design connects directly to standard male DB25 parallel ports without additional adapters
  • Simple plug-and-play hardware with no drivers or power source required
  • Very lightweight at 0.16 ounces, easy to keep in a toolkit or cable bag

👎 Cons

  • Limited to DB25 parallel port devices, which are increasingly rare on modern hardware
  • Requires separate software to actually perform data transfers — no utility is included
  • Female-to-female configuration means you need a cable if your devices do not have male DB25 ports directly accessible
  • Only supports direct device-to-device connections with no signal amplification for longer distances

Frequently Asked Questions

It crosses the transmission and receiving lines between two devices, allowing them to communicate directly through their parallel ports without needing a modem or network connection in between.
It has DB25 female connectors on both ends, designed to plug into the male DB25 parallel ports found on computers and other devices.
Yes, you will typically need file transfer software such as LapLink, Interlink, or a similar direct-connection utility to manage the data transfer between the two connected devices.
This adapter is designed for parallel port (DB25) use. While it physically fits a DB25 serial port, the pin crossover configuration is wired for parallel communication and may not function correctly on serial connections.

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