DIY USB DMX Controller for under $10 – Ethernet Cable

The DMX protocol, widely used in lighting control systems, operates on the same communication standard as the RS485 protocol. This means that any RS485 USB converter can be repurposed to send DMX signals, allowing you to control DMX-compatible devices such as stage lights, dimmers, and other effects. By leveraging this compatibility, you gain a versatile and cost-effective way to interface your computer or lighting software with professional lighting equipment without the need for specialized, often expensive DMX hardware controllers.

Traditional DMX controllers tend to be costly, which can be a significant investment for hobbyists, small venues, or independent artists. This guide provides an alternative approach, showing you how to save money by using an affordable RS485 USB converter as your DMX interface. The money saved on expensive DMX controllers can instead be redirected towards enhancing your setup with additional hardware, such as a MIDI controller for your lighting software, offering more hands-on control and creative possibilities for your lighting projects.

Requirements

Before starting, make sure you have all the necessary components. If you prefer a slightly different build, I have a second USB DMX Controller tutorial available [here]. For this project, it is essential to use a USB-RS485 adapter with an RJ45 output—do not use a USB-Network adapter, as those are incompatible with DMX protocols.

You will need:

• A USB-RS485 network interface adapter

• A female XLR connector (typically a 3-pin XLR).

• A spare network cable (Cat5e or Cat6 recommended).

• Soldering iron and solder tin.

• Wire stripper or cutter.

Make sure your soldering equipment is ready for clean and secure connections, as poor solder joints can cause intermittent signal loss.

Wiring the Cable and XLR Connector

Prepare the Network Cable
Take your spare network cable and cut off one of the RJ45 connectors. Using a wire stripper or carefully with a blade, strip about 2–3 cm of the outer insulation at the cut end to expose the individual wires.

Identify the Wires
You’ll find 8 wires inside, each with a specific color. For DMX control, only use these three wires:

• Orange (Data -)

• Orange-White (Data +)

• Brown-White (Ground)

Cut away the other wires to avoid confusion and reduce clutter.

Prepare the XLR Connector
Disassemble your female XLR connector by unscrewing the back shell. Slide the two back parts of the connector onto the cable now—do this before soldering, as it will be impossible afterward.

Solder the Wires to the XLR
Following the DMX wiring standard, solder the wires onto the XLR connector pins as follows:

• Pin 1 (Ground): Brown-White wire

• Pin 2 (Data -): Orange wire

• Pin 3 (Data +): Orange-White wire

Be sure to make clean solder joints without any short circuits. Once soldered, reassemble the XLR connector housing and screw it back together securely.

Testing
It’s a good idea to make both a short cable and a longer cable to test the system’s flexibility and range. Both should work perfectly if wired correctly.

Software Setup

To control your DMX devices via your new USB-RS485 DMX controller, you’ll need software capable of sending DMX signals.

Freestyler DMX is one of the best free options available. Download and install it from their official website [here].

• In Freestyler, navigate to Settings > Interfaces and select Enttec Open DMX as your interface. This is compatible because it’s based on RS485, which matches your hardware.

• Save the settings, then add your DMX fixtures and start programming your light shows.

Other DMX-compatible software options include:

• DMXControl (free, Windows)

• Martin M-Series Software (includes extensive fixture libraries)

• JV Lightning DMXControl (available on the Mac App Store in free and pro versions)

Optional: Passive DMX Splitter

If you want to control multiple DMX devices from a single output, you might consider using an RJ45 passive splitter.

• Note that passive splitters are generally not recommended for DMX because they can cause signal degradation and interference, especially as the cable lengths increase.

• For reliable and interference-free operation, consider using active DMX splitters/repeaters designed specifically for DMX signal distribution.

FAQ and Troubleshooting

• No signal despite correct wiring?
  Make sure you are using a straight-through network cable, not a crossover cable.

• What’s the maximum cable length?
  Standard network cables can support lengths up to 100 meters. I personally tested up to 15 meters without any issues.

• Driver installation
  Most USB-RS485 adapters use the FTDI FT232 chip, which usually installs drivers automatically on modern OSes. If you’re using Windows XP or an older system, or if the driver is not installing properly, manually download drivers from FTDI’s official site.

• Quick testing software
  For a simple way to verify your DMX controller is outputting signals, use the free DMX Tester from kmtronic.com.