What Is sACN (E1.31)? How It Differs From Art-Net
A DMX universe is limited to 512 channels. In a rig that needs dozens of universes, carrying the data over Ethernet beats pulling a separate cable for each one. Two protocols dominate that job: Art-Net and sACN. They do the same thing with different philosophies.
In short
- sACN is ANSI E1.31, the standard for carrying DMX data over a network.
- It uses multicast by default, far more efficient than Art-Net’s broadcast at scale.
- The priority field (0–200) gives redundancy inside the protocol.
- Multicast addresses derive from the universe number:
239.255.0.1= universe 1. - Art-Net’s advantages are device discovery (ArtPoll) and wider legacy support.
What is sACN?
sACN stands for Streaming ACN and is standardised as ANSI E1.31. It is a stripped-down part of the larger ACN (Architecture for Control Networks) family that focuses purely on continuously streaming DMX data. It sends that data as UDP packets, by default over multicast.
Why multicast matters
Art-Net traditionally uses broadcast: the packet goes to everyone on the network, and even an uninterested device has to receive and discard it, burning CPU. In a 40-universe rig that means every device on the network processing thousands of irrelevant packets per second.
sACN instead assigns each universe its own multicast group. A node subscribes only to the groups it cares about, and a managed switch with IGMP snooping forwards those packets only to subscribed ports. Per-device traffic drops and the system scales comfortably to hundreds of universes.
| Art-Net | sACN (E1.31) | |
|---|---|---|
| Standard | Artistic Licence (open but proprietary) | ANSI E1.31 (formal standard) |
| UDP port | 6454 | 5568 |
| Default delivery | Broadcast (Art-Net 4 also supports unicast) | Multicast |
| Universe count | 32,768 (Art-Net 4) | 63,999 |
| Priority / backup | Not in the protocol | Yes (0–200 priority field) |
| Device discovery | Yes (ArtPoll) | No |
| RDM transport | Yes (ArtRdm) | Separate standard (E1.33 / RDMnet) |
The priority field: sACN’s strongest feature
Every sACN packet carries a priority value from 0 to 200, defaulting to 100. When more than one source transmits to the same universe, the receiver follows the highest priority source. That is a redundancy mechanism built into the protocol itself.
In practice: the main console transmits at priority 100 and the backup at 90. When the main console drops out its stream stops, receivers notice the source has vanished after a timeout, and they fall over to the priority-90 backup automatically. Getting the same behaviour with Art-Net requires an external merge or backup device.
How multicast addresses are derived
sACN embeds the universe number directly in the multicast IP address, following this pattern:
239.255.. Universe 1 -> 239.255.0.1 Universe 2 -> 239.255.0.2 Universe 256 -> 239.255.1.0 Universe 300 -> 239.255.1.44
This is genuinely useful when troubleshooting: in a packet capture you can tell which universe is flowing just by reading the destination address.
Which should you choose?
- Large rig, many universes, redundancy required: sACN. Multicast scales, and the priority field solves backup at the protocol level.
- Device discovery and broad legacy support matter: Art-Net. ArtPoll finds nodes on the network automatically, and older equipment support is wider.
- Small rig: either works; pick whichever your node and console support best.
The network matters more than the protocol
Whichever you choose, keep the lighting network separate from the production network. Use managed switches, enable IGMP snooping for multicast, keep lighting traffic on its own VLAN, and never run a live show over Wi-Fi. A few milliseconds of jitter on a wireless link turns into visible stutter on moving heads.
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