---
title: "Extension Port"
description: "Learn how to extend the functionality of your JetKVM device through the customizable RJ-11 extension port."
order: 6
---

The **JetKVM** features an **RJ-11 extension port** on the back, designed to provide full customizability and flexibility to your device. Whether you're looking to integrate additional hardware capabilities or contribute custom add-ons, the extension port opens up unlimited possibilities for expansion.

<img
  src="/device-back-port-extension-port-2.png"
  alt="Back of JetKVM device"
  style={{ width: "100%", maxWidth: "320px", marginBottom: "40px" }}
/>

## What is the Extension Port?

The **RJ-11 extension port** functions as a serial port, allowing communication with the JetKVM. This port is key to adding extra hardware and functionality to the device, making it a highly versatile component.

These add-ons are available for purchase, but the port isn't limited to just JetKVM's accessories—**it's open for anyone to develop their own custom extensions**.

### ATX Power Control

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  <img
    src="/atx_extension_preview_2.png"
    alt="ATX Power Control"
    style={{
      margin: "0 auto",
    }}
  />
</Card>
A control board that manages computer power states. It also includes a USB-C port for connecting
a 5V power supply. This can then power the JetKVM through the RJ11 cable. Alternatively, 5V
power can be supplied through a pin header.

The ATX Power Control comes with a PCIe slot cover bracket, allowing for clean cable routing through your PC case - without requiring an actual PCIe slot.

Each pin features dual headers: one set for KVM control and another for the original front panel buttons—meaning you don't have to choose between them. Both can be connected simultaneously.

### DC Power Control

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  <img
    src="/dc_extension_preview_2.png"
    alt="DC Power Control"
    style={{
      margin: "0 auto",
    }}
  />
</Card>

The DC Power Control extension enables power management for connected DC-powered devices, such as mini PCs or NAS units, using a standard 5.5×2.5 mm connector. It supports DC input ranging from **12 to 20 volts**, and we're **including adapters to support 5.5×2.1 mm** connections as well.

Included in the extension package:

- Extension board (pictured) + Case (In Design)
- 1x 5.5/2.5 mm male to 5.5/2.5 mm male cable
- 1x 5.5/2.1 mm female to 5.5/2.5 mm male adapter
- 1x 5.5/2.5 mm female to 5.5/2.1 mm male adapter

Note: the extension can **also power the JetKVM itself through the RJ-11 connection**, streamlining setup and reducing the need for additional power sources.

### Serial Console

Direct access to the device's serial console for diagnostics and low-level control. Unlike the other extensions, that ship with the JetKVM device, this extension will ship separately. We're actively developing it, but a 3D render is not yet available.

## Customizing with the Extension Port

By using the extension port, developers and hardware enthusiasts can add a variety of features, for example:

- **Temperature Sensors**: Monitor temperature for environmental controls.
- **Mechanical Button Pressers**: Automate physical interactions with connected devices.

If you have specific needs for your workflow or want to create fun projects, the extension port provides the flexibility to build and experiment.

We encourage the community to build custom add-ons for JetKVM.
If you create a hardware extension that works with the RJ-11 extension port, you'll be able to **submit a pull request** to the JetKVM project once the source code becomes available in early December when the first devices ship. We enthusiastically welcome contributions from the community and look forward to collaborating on new features that benefit all JetKVM users.

## Build your own extensions

The extension port is designed to unlock endless opportunities for hardware modifications. Using a standard RJ-11 connector, it provides power, I2C, and GPIO pins that make it easy to develop your own custom extensions.

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  <img
    src="/extension_port_pinout.png"
    alt="Extension Port Pinout"
    style={{ margin: "0 auto" }}
  />
</Card>
We're excited to see what creative solutions you'll build! Whether you're developing something
for your personal use or planning to share it with the community, we're committed to supporting
developers who want to contribute.
