What Is DALI? IEC 62386 and Digital Lighting Control Basics
DMX512 was designed for the stage: fast, one-way, continuously streaming data. Controlling 400 luminaires in an office building is a completely different problem — there you need individual addressing, feedback and fault reporting rather than speed. That is exactly what DALI is for.
In short
- DALI is a bidirectional digital lighting control protocol defined by IEC 62386.
- One line carries 64 addresses, 16 groups and 16 scenes.
- 1200 bit/s is slow but noise-tolerant and makes wiring rules very relaxed.
- Scene levels are stored in each luminaire’s own memory.
- Its real strength is feedback: faults, levels and emergency test reports.
- It is unsuitable for fast stage effects — that remains DMX512 territory.
What DALI is
DALI stands for Digital Addressable Lighting Interface and is defined by IEC 62386. It is a bidirectional digital lighting control protocol running over a two-wire bus.
That bidirectionality is the key difference: a DALI controller does not only issue commands, it can ask questions. “What level are you at?”, “is your lamp failed?”, “how many hours have you run?” — the luminaire answers.
The core numbers
| Property | Value |
|---|---|
| Data rate | 1200 bit/s |
| Addresses per line | 64 individual devices |
| Groups | 16 |
| Scenes | 16 |
| Bus voltage | 9.5 – 22.5 V DC (typically 16 V) |
| Bus current | 250 mA maximum |
| Current per device | 2 mA maximum |
| Cable | Two cores, mains-rated insulation; polarity free |
| Maximum run | ~300 m (with 1.5 mm²), 2 V maximum voltage drop |
Why is 1200 bit/s so slow?
Because speed is not the point. DALI was designed to fade a luminaire smoothly over four seconds, not to update positions 44 times a second. The low rate buys something valuable: the signal is extremely tolerant of noise and the wiring rules are very relaxed. You can run a DALI line in the same containment as mains cable — something you would never contemplate with DMX.
Addressing, groups and scenes
A command can reach a luminaire three ways:
- Broadcast — everyone on the line. Used before commissioning and in simple systems.
- Group — one of groups 0–15. A luminaire can belong to several groups at once, which is far more flexible than anything in DMX.
- Individual address — a single luminaire, 0–63.
Scenes are a separate layer: each luminaire stores its own target level for each of 16 scenes in its own memory. The controller only says “go to scene 4” and every luminaire moves to its stored value. That reduces bus traffic to almost nothing and keeps scenes working even if the controller fails.
Feedback: DALI’s real value
With 800 luminaires in a shopping centre it can take weeks to notice one has failed. DALI removes that: the system polls each device and reports the faulty one. Typically readable:
- Current light level
- Lamp or driver failure
- Device presence on the line (detecting missing devices)
- Test results and battery status on emergency luminaires
Emergency lighting testing
One of DALI’s strongest use cases is emergency lighting (IEC 62386-202). The periodic function and duration tests required by regulation are run by the system itself, logged and reported. For a facilities team, reading a report instead of walking the building with a test key is on its own a reason to move to DALI.
Why the wiring is so relaxed
DALI topology is free: star, tree, bus or any mixture. The only prohibition is a ring. On most devices polarity does not matter either, so swapping the two conductors causes no harm.
Compare that with DMX, where the only correct topology is a daisy chain, termination is mandatory and cable impedance is critical. DALI’s low speed removes all of those constraints. The fact that an electrician can pull it as ordinary two-core cable using familiar methods is the main reason DALI dominates architectural projects.
What DALI is not good at
- Fast effects. At 1200 bit/s you cannot run chases, strobes or moving heads.
- Colour-heavy stage work. DALI supports colour control (Part 209, DT8) but its response time is not suited to live performance.
- More than 64 devices on one line. Beyond that you need additional lines and an application controller to manage them.
For a detailed look at which protocol suits which job: DALI or DMX512?
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