Art-Net explained: DMX over Ethernet

What is Art-Net?

Art-Net is DMX over IP: a protocol, published by Artistic Licence, that carries DMX512 lighting data over a standard Ethernet network instead of dedicated DMX cable. A physical DMX512 line carries exactly one universe (512 channels); with Art-Net, a single Cat5e or Cat6 run can carry many universes at once, and the protocol works on almost any pre-existing network infrastructure: ordinary switches, ordinary cable, no special hardware in the middle. Because the specification is royalty-free, almost every lighting console, PC software package, and network node supports it. The full specification is available on the official website: https://art-net.org.uk/

The important thing Art-Net does not do is talk to fixtures directly. Your moving heads and dimmers still expect DMX512 on XLR. Art-Net covers the long haul from your controller to a node, and the node converts back to physical DMX for the last stretch. If you are not yet sure what a DMX universe is, read what a DMX universe is first; everything below builds on it.

How DMX rides on UDP/IP

Art-Net's workhorse packet is called ArtDmx. Each ArtDmx packet carries one frame of one universe (up to 512 channel values) plus a header identifying which universe the data belongs to. Your controller sends a continuous stream of these packets, typically around 40 to 44 per second per universe to match the practical refresh ceiling of DMX512 itself, and every receiving device reads the header and acts only on the universes it is configured to listen to.

All Art-Net traffic uses UDP port 6454. You will sometimes see this written as 0x1936, which is the same number in hexadecimal; a few older documents (including an earlier version of this article) quote "port 1936", which is incorrect. If a firewall or router blocks UDP 6454, Art-Net stops working, so this is the first number to memorise.

Because it is UDP, there is no handshake, no acknowledgement, and no retransmission of lost packets. That sounds fragile, but it suits lighting well: a lost frame is overwritten by the next one within tens of milliseconds, and the low overhead keeps latency down. The flip side is that Art-Net rewards a clean, wired network; on congested or wireless links, dropped packets show up as stuttering fades. Wi-Fi can work for small rigs, with caveats covered in sending Art-Net and sACN over Wi-Fi.

Bandwidth is rarely the constraint. One universe at 44 packets per second is roughly 0.2 Mbit/s, so even a 100 Mbit link can carry dozens of universes with headroom. The real scaling limit on larger systems is how the packets are addressed, covered under unicast and broadcast below.

Universe addressing: Net, Sub-Net, and Universe

Art-Net does not number universes with a single flat integer. Since Art-Net 3, the full address of a universe (the spec calls it a Port-Address) is a 15-bit value split into three fields, which you will see in every node's configuration page:

That gives 32,768 possible Port-Addresses. Earlier versions of the protocol (Art-Net I and II) only had the Sub-Net and Universe fields, for 256 universes, which is why some older gear ignores the Net field entirely. For small rigs you can leave Net and Sub-Net at 0 and just count universes 0 to 15; the higher fields only matter once a rig grows beyond 16 universes.

Two practical traps follow from this scheme:

• The transmitter and the node must agree on all three fields. A node configured for Net 0, Sub-Net 0, Universe 1 will silently ignore data sent to Net 1, Sub-Net 0, Universe 1.
• Software vendors disagree on whether universes count from 0 or from 1. Art-Net itself starts at Universe 0, but many consoles and apps label the first universe "1" in their user interface. If your fixtures respond one universe off, or not at all, check whether the sending software's "Universe 1" is actually Art-Net universe 0 on the wire. Most node configuration pages (including ENTTEC's) show the raw Net/Sub-Net/Universe values, the unambiguous reference when two products disagree.

IP addressing: the 2.x.x.x convention

The Art-Net specification defines two default address ranges: a primary network of 2.x.x.x and a secondary of 10.x.x.x, both with netmask 255.0.0.0, with each device deriving the rest of its address from its MAC address so that two out-of-the-box devices will not clash. This convention exists so lighting gear can find itself on an isolated network with no router or DHCP server present, and it is why many Art-Net nodes ship on a 2.x.x.x address (ENTTEC's current gateways, the ODE MK3 and DIN Ethergate, instead default to DHCP, falling back to 192.168.0.10 if no DHCP server responds).

You are not locked to it. Art-Net works fine on an ordinary 192.168.x.x home or office network, as long as every device (computer and nodes) sits in the same IP range with the same netmask. What matters is consistency: mismatched netmasks are the number-one cause of "my node shows up but receives nothing" (see the troubleshooting table below). If you need to set a static address on your computer to match your nodes, follow changing your IP address on Windows or on macOS.

Unicast vs broadcast: why broadcast floods larger networks

An Art-Net transmitter can address its packets two ways:

• Broadcast: the packet is sent to the whole network (for example 2.255.255.255), and every device receives every universe, then discards what it does not need.
• Unicast: the packet is sent to one specific node's IP address, so each device receives only the universes intended for it.

Broadcast is convenient: no per-node configuration, and everything "just works" on a small network. It scales badly for a specific reason: Ethernet switches cannot filter broadcast traffic, so every node, console, and laptop on the network must inspect each packet in software just to discard the ones it does not want. At tens of universes, low-powered nodes start spending significant CPU time discarding traffic they never wanted, and some begin dropping the packets they actually need.

Art-Net II fixed this by pairing the discovery mechanism that had existed since the original specification with unicast delivery. A controller broadcasts an ArtPoll packet, each node answers with an ArtPollReply describing its IP address and which universes it handles, and the controller then unicasts each universe only to the nodes that subscribed to it. The Art-Net 4 specification directs controllers to use unicast where possible, and most modern software does so by default.

A sensible rule of thumb: broadcast is fine up to a handful of universes on a dedicated lighting network; switch to unicast as the universe count grows or when lighting shares a network with anything else. For sizing anything beyond a few universes, see bandwidth planning for eDMX networks. sACN takes a different approach to the same problem, using multicast groups that switches can prune; the trade-offs are compared in Art-Net vs sACN: which should you use?

Where Art-Net fits vs plain DMX512 cabling

Art-Net does not replace DMX512; it moves the distribution problem onto a network. A direct DMX line remains the simplest option when one universe within cable reach is enough: it is a daisy chain, it needs no IP configuration, and it is electrically robust over long runs. Art-Net earns its complexity when you need any of the following:

• More than one or two universes from a single controller output.
• Long distances: Ethernet runs 100 m per segment, and switches or fibre extend that indefinitely.
• Use of existing structured network cabling instead of pulling new DMX lines.
• Multiple sources or destinations on one backbone (console plus backup, media server plus pixel controller).

The cost is that you now own a small IP network: addresses, netmasks, and a switch become part of your signal path, and the usual termination and cabling rules still apply on the DMX side of the node.

The typical hardware chain

Every Art-Net rig has the same four-stage shape:

Controller or software → Ethernet network → Art-Net node → DMX fixtures

• Controller/software generates the channel data: a lighting console with an Ethernet port, or software on a computer. ENTTEC's EMU (DMX control and sound-to-light) and ELM (LED pixel mapping) both output Art-Net and are free to download, unlike dongle-locked alternatives, so either is an easy way to get test data onto the network.
• Network: any standard gigabit switch and Cat5e/Cat6 cable. Nothing lighting-specific required, though a dedicated switch for lighting traffic avoids competing with other services.
• Node: the converter that receives Art-Net packets and regenerates physical DMX512. The ODE MK3 is a compact two-universe node with two bi-directional XLR5 ports, each configurable as DMX input or output, and the DIN Ethergate is the DIN-rail-mounted equivalent for permanent installations.
• Fixtures daisy-chain from the node's DMX port exactly as they would from a console.

For a step-by-step first-time configuration of that chain, see setting up an Art-Net to DMX converter node.

Troubleshooting: Art-Net broadcast and netmasks

If your device is not receiving directed Art-Net broadcast, ensure that both your transmitting and receiving devices have an identical netmask and are in the same IP range. The table below shows an Art-Net transmitter at 10.0.0.100 and a receiver at 10.0.1.45:

Troubleshooting: ArtPoll discovery

If your software cannot detect a node:

• Confirm your computer is on the same local network as the node: same IP range, same netmask, connected to the same switch. ArtPoll discovery does not cross routers.
• Check that no firewall on the computer, and no router in the path, is blocking UDP port 6454.
• On managed switches, check for broadcast storm control or broadcast rate limiting, which can silently drop the ArtPoll broadcasts that discovery depends on.

To rule the network in or out, plug the node directly into your computer with a single cable and confirm it answers with an ArtPollReply. Then reintroduce switches one at a time between the computer and the node until discovery breaks; the last piece of equipment added is where the problem lies. For the wider checklist (wrong universe, off-by-one addressing, merged sources), see Art-Net/sACN troubleshooting.