Art-Net vs sACN: which protocol should you use?

Addressing and transport

Both stream DMX512 over plain UDP. Almost everything about addressing differs.

Behaviour under load and failure

This half decides what the rig does at the worst possible moment.

Management and ecosystem

Here the two barely overlap: one manages devices, the other does not try.

Priority versus merging: the difference that decides a backup console

Every sACN data packet carries a priority octet, and the rule is blunt: for a given universe, a receiver gathering data from several sources treats the highest priority as the definitive data. Sources without variable priority must send 100. Put a backup on 90 under a main source on 100 and it sits silent until the main source stops, then takes the rig instantly.

Art-Net has no priority field at all. When ArtDmx for one Port-Address arrives from two IP addresses, a node either flags an error and waits for a human, or merges, HTP or LTP as set by ArtAddress. Then comes the limit: merging is limited to two sources, and any additional sources are ignored by the node. A failed source is held in the merge buffer for 10 seconds.

So an sACN backup stays invisible until needed, while an Art-Net backup is merged all the time, and a third source is not degraded, it is discarded.

Discovery, and the broadcast rule everyone gets wrong

Art-Net's discovery layer is not optional: all controllers must broadcast an ArtPoll every 2.5 to 3 seconds, and in Art-Net 4 every reply must be unicast. A reply carries the node's universes, RDM capability and status, which is what the rest of Art-Net's management is built on.

sACN discovers universes only: sources advertise which universes they are transmitting on universe 64,214 every 10 seconds. No device list, no names, no configuration, and the standard states plainly that no mechanism is specified for discovering unicast addresses. Traffic is partitioned by multicast instead, the universe number forming the last two bytes of the address: universe 1 is 239.255.0.1.

Art-Net 4 does the opposite of what most articles claim. ArtDmx must be unicast to subscribers of the universe in the packet, and the specification states there are no conditions in which broadcast is allowed. Subscription comes from discovery, so discovery decides where data may go. Note the asymmetry: ArtDmx is unicast only, ArtSync is directed broadcast only.

On that gap the specification is blunt, in its owner's words rather than as neutral fact: sACN lacks any ability discover devices, configure devices or transport RDM data. The factual core holds: E1.31 defines neither.

Universe counts and the off-by-one

Art-Net's 15-bit Port-Address gives 32,768 theoretical universes, of which 1 to 32,767 are valid, because Art-Net 4 deprecates zero to improve sACN compatibility. sACN allows 1 to 63,999, with 0 and 64,000 to 65,535 reserved apart from 64,214 for discovery.

Then the numbering trap. Art-Net counts from zero on the wire, sACN from one. DMXDesktop numbers universes from 1 on every protocol, so DMXDesktop universe 1 goes out as Art-Net universe 0, and a node showing a number one lower than you set is not broken.

RDM, configuration and standards status

RDM. Art-Net carries it, via ArtRdm plus ArtTodRequest and ArtTodData for the device table, but it is not an ESTA standard: ANSI E1.20-2025 does not reference Art-Net at all. sACN carries no RDM whatsoever, so no product can offer it however it is marketed. RDM over IP is ANSI E1.33 (RDMnet). DMXDesktop runs RDM over USB interfaces and over Art-Net.

Configuration. Art-Net sets a node's universes, IP address and port direction using ArtAddress, ArtIpProg and ArtInput, and Art-Net 4 added commands selecting whether a port converts sACN or Art-Net. sACN configures nothing.

Standards status. sACN is an open American National Standard from ESTA, free to download and free to implement. Art-Net is proprietary, owned by Artistic Licence, royalty-free but conditional: implementers apply for an OemCode and must credit Art-Net(TM) Designed by and Copyright Artistic Licence in the user guide. Port 5568 is IANA registered as sdt; 6454 is not registered at all.

What happens when the data stops

Both run over UDP, so what matters is how a receiver treats silence. sACN treats 2.5 seconds with no data packets as network data loss for that source and universe, and the 2025 revision counts data packets specifically, so a source still sending discovery packets will still time out. Here is the part most people get wrong: E1.31 requires a mode where, on loss of data from all sources of a universe, the gateway immediately stops transmitting DMX512. Hold-last-look is an allowed extra, not the requirement.

Art-Net's 3 second figure is a discovery timeout, not a data one, and its data-path defaults lean the other way: an output port re-transmits the same frame continuously without ArtDmx, and if both merge sources fail the output holds the last merge result. Pick the behaviour you want and set the node to match.

Which should you use

• A couple of nodes in a small rig. Either. sACN is marginally simpler, because the group comes from the universe number and you never type an IP address.
• A large install. sACN. Each node receives only the universes it joined, and 1 to 63,999 leaves room to number by area.
• A rig needing a backup console. sACN, for the priority field. A two-source merge is not a failover scheme.
• A rig where you want to configure nodes and run RDM. Art-Net. It discovers, configures and runs RDM; sACN attempts none of it.
• A mixed rig running both. Normal, and Art-Net 4 anticipates it: Art-Net for discovery, management and RDM, sACN for the live control data, chosen per gateway port.

Neither is simply better: sACN bought arbitration, multicast and an open standard by leaving management out, and Art-Net bought discovery, configuration and RDM without ever gaining a priority field.

Running both in DMXDesktop

DMXDesktop outputs Art-Net and sACN at once on Mac and Windows, configured per row, so one universe can go out over sACN to a multicast group and over Art-Net to a node.

• Priority is sACN only. Per universe, 1 to 200, default 100. That is the app's range; E1.31 permits 0 to 200. Art-Net rows carry no priority byte, so Priority merge mode is not offered there.
• Multicast is a switch. On, the address is derived as 239.255.X.Y. Off, you type the destination.
• Art-Net discovery is automatic. DMXDesktop polls every 2.5 seconds and answers inbound polls. sACN sources are found passively, since sACN has nothing to announce with.
• Receiving either protocol needs Pro. Sending works on every plan, within its universe limit.