Concepts & signal flow
DMX / sACN / Art-Net / RDM help
The DMX / sACN / Art-Net / RDM questions live-event techs bring to Ask Roadie most (also called Art Net, ArtNet, DMX, DMX512). Pick your symptom, or describe your own in plain words, and get the likeliest fix first, with the manual page when there is one.
Common DMX / sACN / Art-Net / RDM questions
What techs run into most, and what's usually behind it. The step-by-step fix for your exact topic is in Ask Roadie.
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Art-Net node works but bogs down the network / other gear sees lag
Short answer: Broadcast Art-Net scales badly because it hits every NIC; unicast or multicast confines each universe to the devices that need it, and isolating the lighting LAN keeps broadcast off unrelated gear.
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How many fixtures on one DMX line, and how long can the run be?
Short answer: The 32-unit-load and cable-length limits come from the RS-485 electrical layer DMX rides on; splitters re-drive the signal for each branch and Ethernet transport removes the single-universe channel ceiling.
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RDM discovery finds no fixtures (or fixtures misbehave when RDM is on)
Short answer: RDM is bidirectional on the DMX pair; any device in the chain that can't pass the reply, or a transport (sACN) that has no RDM channel, breaks discovery, while non-RDM fixtures can misread the extra RDM traffic.
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sACN fixtures not responding / receiving nothing
Short answer: sACN/E1.31 derives the destination multicast address directly from the universe number, so an off-by-one universe silently sends the data to a group nobody is listening to.
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sACN works on a small rig but floods/chokes the network as it grows
Short answer: sACN uses IP multicast; IGMP snooping is what lets a switch prune multicast to only subscribed ports, which is the difference between a clean large network and a broadcast storm.
Not on the list? Describe it your way, or paste the error code off the display. Ask Roadie works the problem with you until it's fixed or you have a clear next move.
How Ask Roadie helps with DMX / sACN / Art-Net / RDM
- 1. Pick DMX / sACN / Art-Net / RDM. It's already in the list.
- 2. Describe what you're seeing. In your own words, or the error code off the screen.
- 3. Get the likeliest fix first. Steps in order, the manual page when there is one, and a note when other techs have confirmed it.
- 4. Still broken? Tap 👎 and it keeps going from where you left off.