USB DMX adapters with LMS — what works

LMS can drive DMX straight from a USB adapter, without a network node.

What is supported

Open DMX is Windows-only, and that is not an oversight

Open DMX adapters are raw FTDI chips with no microcontroller — the host has to generate the DMX break timing itself. LMS does this through the FTDI D2XX driver, which is a Windows component. The browser Web Serial API cannot do it: it has no way to hold the line low for a break of the right length, so the protocol simply cannot be produced that way.

If you are on macOS or Linux, use a network node (Art-Net or sACN) instead.

⚠ The serial number gotcha

An FTDI device that is already open reports an EMPTY serial number.

If you have two adapters, or LMS is already using one, enumerating by index will happily give you the wrong device or a blank entry — and the symptom is that the adapter you want simply is not in the list, or output goes to the wrong one.

Key on the serial number, not the position in the list. If a device shows a blank serial, something else already has it open — close the other application first.

Choosing between USB and a network node

USB DMX is simple, cheap and has one cable. But it is one universe, tied to one machine, and it is Windows-only for Open DMX.

A network node costs more but gives you multiple universes, puts the machine anywhere on the network, and works from any platform. For anything beyond a single fixture run, a node is usually the better answer.