Art-Net vs sACN for Exhibit Lighting: Which to Use and Why

Both Carry DMX512 Over Ethernet

Art-Net and sACN solve the same problem: DMX512 is limited to 512 channels per cable and needs a physical run to every fixture. Putting DMX inside Ethernet packets removes both limits — many universes over one network cable, and network topology instead of daisy-chained bus.

Underneath, the payload is still DMX512. Both protocols carry the same 512 bytes of channel data per universe. A fixture does not know or care which one delivered it; the node converting to physical DMX does.

That has a practical consequence worth stating early: choosing between them is a network-layer decision, not a lighting-design decision. Nothing you can do in one is impossible in the other.

The Comparison That Matters

The two things that actually bite

1. Universe numbering is off by one between them.
Art-Net universes start at 0. sACN universes start at 1. So Art-Net universe 0 and sACN universe 1 are "the first universe" in each system.

Half the gear in the field papers over this by displaying whatever its manufacturer preferred, and a node set to "universe 1" may or may not mean the same thing as a console set to "universe 1." When your fixtures respond to the wrong universe or to nothing at all, and the numbers on both screens look identical, this is the first thing to check.

2. Broadcast versus multicast is a network-health issue, not a preference.
Art-Net's broadcast means every device on the subnet receives every lighting packet — including the projector PCs, the media players and the touchscreen. On a small dedicated lighting network this is harmless. On a shared exhibition network with 40 universes running at 40 Hz, it is a meaningful load on devices that have nothing to do with lighting.

sACN's multicast lets managed switches deliver packets only to ports that subscribed. But this only works if the switch supports IGMP snooping and it is enabled. On an unmanaged switch, multicast degrades to broadcast and you are back where you started — with the added irony of having chosen sACN specifically to avoid that.

Recommendation for exhibition work: use sACN if the gear supports it and the switches are managed; use Art-Net on a physically separate lighting network if not. What you should avoid is Art-Net at scale on the same VLAN as everything else.

sACN Priority: The Feature Art-Net Lacks

sACN packets carry a priority value from 0 to 200 (default 100). When two sources send the same universe, receivers honour the higher priority.

In an exhibition this is genuinely useful: a show controller runs the scheduled scenes at priority 100, and a maintenance console can take over at priority 150 without anyone unplugging anything, then release it. Art-Net has no equivalent — two sources on the same universe simply fight, and the result depends on packet timing.

If your installation will ever have a permanent controller and a portable console, this alone is a reason to choose sACN.

DMX512 Wiring: Still the Physical Layer

Whatever runs over Ethernet, the last hop to the fixtures is DMX512 over RS-485, and its rules are strict:

• Daisy-chain only. Node → fixture → fixture → fixture. No star, no Y-splitters. Passive splitters are one of the most common causes of flicker.

• 120 Ω terminator at the last fixture. Not optional on long runs. Missing termination causes reflections, and the symptom is random flicker that gets worse the longer the run — often mistaken for a bad fixture.

• 512 channels per universe. An RGB fixture uses 3, RGBW 4, a moving head 16–32. Universes fill up faster than people expect.

• Addresses must not overlap unless you deliberately want fixtures to mirror each other.

• Use proper DMX cable (120 Ω), not microphone cable. Mic cable is 60 Ω and works right up until the run gets long or the hall gets electrically noisy — then it produces intermittent faults that are extremely hard to trace.

• Max ~32 devices per chain before you need a splitter/repeater.

A note on "it works on the bench": almost every DMX wiring shortcut works over three metres on a desk. Termination, cable impedance and star topology only bite at installation length. Do not validate DMX wiring practice on a bench test.

When to Use Neither

Art-Net and sACN are for lighting fixtures that speak DMX. A lot of exhibition "lighting" is not that:

• Architectural lighting on relays or dimmer packs — often Modbus or dry contacts. See Modbus RTU vs TCP.

• Building lighting on KNX or DALI — a different world entirely, usually the building contractor's.

• A single colour-changing wash on a small exhibit — sometimes just a manual controller, and adding a network protocol to it is over-engineering.

The question to ask is not "which protocol" but "what does the fixture actually have on the back of it." If it has a 3-pin or 5-pin XLR, you are in DMX land. If it has a relay input or an RS-485 terminal block labelled A/B, you are probably in Modbus land.

Troubleshooting

Nothing responds at all
Check universe numbering first (the 0-vs-1 problem). Then check that the sender and node are on the same subnet — Art-Net broadcast will not cross a router. Art-Net traditionally uses the 2.x.x.x or 10.x.x.x ranges; a node still on a factory 2.0.0.x address will be invisible to a controller on 192.168.1.x.

Fixtures respond but the wrong ones move
Address overlap, or a channel-count assumption that is wrong for that fixture's operating mode. Many fixtures have multiple modes (e.g. 8-channel vs 16-channel) selected on the fixture itself.

Random flicker
Termination, cable type, or a passive splitter. In that order.

Works, then stutters when the media plays
Network contention — this is the Art-Net broadcast problem. Move lighting to its own VLAN or physical network.

Works from one console, not from the show controller
If both are connected, sACN priority may be the explanation — the other source is winning.

With SoftControl

SoftControl drives exhibition devices over TCP, UDP, HTTP, PJLink, serial and Modbus, and in practice a hall's lighting is often reached through the lighting controller or node's own control interface rather than by generating DMX directly — the show controller tells the lighting system which scene to run, and the lighting system does the DMX.

Being straight about scope: SoftControl is not a lighting console and does not replace one for fixture-level DMX programming. Where it fits is the layer above — one interface where "open the hall" powers the projectors, wakes the media PCs, and triggers the lighting scene, instead of three separate systems the operator has to touch in the right order.

For the wider protocol picture see AV control protocols explained.