Practicals on a DMX channel: Zigbee bulbs driven from the console

Practicals are the lamps that are in the shot: a table lamp, a ceiling fixture, a shop sign. On most sets they are smart bulbs with an app, and the gaffer ends up asking someone to "turn that one down a bit" through a phone. We wanted them on a DMX channel like everything else — including when the set is on a mobile network.

What it does

Every beam node can run a Zigbee bridge. It receives the sACN universes the node already sees — from the relay or from a console on the same network — and translates patched channels into commands to an IKEA Dirigera hub on the node's local network. Each bulb gets a DMX address and a profile: single-channel dim, two-channel dim + colour temperature, or dim + hue + saturation for colour bulbs. From the console's point of view the practicals are just fixtures on a universe.

Everything from the dashboard

Nothing is configured on the node by hand. The node's Zigbee tab in the dashboard discovers hubs on the local network, pairs a hub with the press-the-button flow, and then lists every bulb the hub knows — grouped by room, with an online/offline dot and an on/off toggle to identify it. A + Patch button on a bulb row assigns a DMX address; an auto-patch mode ticks a whole room and hands out consecutive addresses. Bulbs can be moved to any universe the node routes.

Config is versioned and pushed to the node over its WebSocket link, so a change made in a browser on the desk reaches a node on 4G in a second and survives a reboot.

What it took to make it reliable

• Zigbee is not DMX. A bulb accepts a handful of commands per second, so the bridge sends on change, throttles per bulb (about seven updates a second) and lets the bulb's own transition smooth the fade. Faders feel continuous; the network is not flooded.
• Hubs flap. A hub on weak WiFi or a bad PSU disappears for a few seconds and comes back. The bridge has a per-hub circuit breaker and rebuilds its fixture list on a 15-second loop, so a hub that comes back is picked up without anyone restarting anything.
• Tokens live on the node, but travel with the org. The pairing token is stored centrally, so a hub with 112 devices moved from one node to another came up without re-pairing.
• More than one hub per node. Since August 2026 a node drives several Dirigera hubs at once; bulbs are addressed to the hub they belong to.
• Its own network on set. The node runs DHCP and can bring up a WiFi access point, so the hub simply joins the node's network — even when the node's only uplink is 4G.

The alternative: our own coordinator

The Dirigera is convenient because the bulbs are already on it. It is also a consumer hub with a consumer API. In parallel we run a Sonoff Dongle Plus MG24 with Zigbee2MQTT on a node: same sACN bridge, MQTT instead of the hub's HTTPS. In tests it was more stable and faster than the Dirigera, and it adds real Zigbee groups — one multicast command for a whole room, ideal for cues and slow fades. It is in test operation on one node; the dashboard integration is next.

Where it has run

Practicals on a Zigbee bridge have run on live productions over the summer of 2026, alongside the main DMX rig and over 4G. The typical setup: a beam node in the set with the hub on its WiFi, bulbs patched to a spare universe, the desk operator treating them like any other channel.