A two-wire digital bus defined by IEC 62386. Each driver carries its own address, so groups, scenes and zones live in software rather than in the wiring — and the bus talks back.
Cable length scales with cross-section — roughly 100 m at 0.5 mm², 200 m at 1.0 mm², 300 m at 1.5 mm². Bus, star and tree topologies are all permitted and no termination resistors are required.
Power and data share the same pair of wires, and the polarity does not have to be observed — two details that make DALI markedly more forgiving to install than its reputation suggests.
Instead of holding a voltage, the controller sends addressed commands down the bus. Each driver listens for its own address, its group, or a broadcast. That is why a fixture can be moved between zones without anyone touching a cable.
Levels use a standardised logarithmic dimming curve across an arc power scale of 0 to 254, which maps to how the eye actually perceives brightness rather than to raw output. The practical result is that the same commanded level looks the same across compliant drivers from different manufacturers — the consistency 0-10V cannot promise.
And it is bidirectional. The bus can be queried: current level, driver status, lamp failure. A fault becomes a reported address rather than a search.
The original standard covered control gear — the drivers. Interoperability between manufacturers was real but uneven, and control devices sat outside the specification.
Restructured IEC 62386 to include control devices — application controllers, sensors and input devices — and added far more rigorous certification testing, with interoperability as the explicit focus. This is what you should be specifying.
Certification for intra-luminaire DALI: the driver supplies its own bus power and stores standardised luminaire, energy and diagnostic data. The basis of smart-ready fixtures and per-fixture energy reporting.
It carries real costs alongside the capability, and they are worth understanding before you commit to it.
None of that argues against it. It argues for deciding early, while it is still a line on a drawing.
Lutron Caséta is phase-cut only. RadioRA 3 adds 0-10V but not DALI. Native DALI in that ecosystem means HomeWorks — a significant step up for what is often a modest number of zones.
We bridge it instead. Our DALI-to-MQTT controller addresses the drivers directly on the bus and exposes them to the control system you actually wanted, talking to the Lutron Smart Bridge PRO over LEAP — Lutron’s local API, certificate-authenticated over TLS. A keypad press is read straight off the bridge and issued as a DALI command:
Specify the PRO bridge. Caséta exposes LEAP integration on the Smart Bridge PRO (L-BDGPRO2) — not the standard Smart Bridge. On RadioRA 3 it is the RR-PROC3 processor. Getting this wrong is a cheap mistake to make and an annoying one to discover on site.
Bridged control excels at scene recall, set-level and on/off. Native control still gives the smoothest continuous hold-to-dim ramps.
The question worth answering first is not whether DALI is better — it is whether your project will still be changing in three years. If the answer is yes, the conversation is short.