DALI (Digital Addressable Lighting Interface) has been the standard for professional lighting control since IEC 60929 in 1999. DALI-2, standardised as IEC 62386 Part 1 (published 2014, revised 2022), changed the game in three fundamental ways: mandatory interoperability certification, multi-master bus operation, and standardised device type definitions. Understanding the differences is essential before specifying any lighting control system.

What DALI-1 was

The original DALI standard (IEC 60929) defined a 2-wire bus running at 1200 baud between a single master controller and up to 64 slave ECGs (Electronic Control Gear — ballasts, LED drivers). The master sent commands; slaves executed them. No certification was required — any manufacturer could claim DALI compatibility. In practice, this produced interoperability failures: a Helvar controller might not correctly communicate with a Tridonic driver despite both claiming DALI compliance. The 16-scene store and group assignment were defined, but the specific behaviour on power restoration, fade rates and scene values varied between manufacturers.

DALI-2: three key changes

Multi-master operation: DALI-2 allows multiple bus controllers (application controllers, push-button interfaces, presence sensors, astronomical clocks) to co-exist on the same DALI bus and independently send commands. A DALI-2 pushbutton input device can send a scene command directly to ECGs without going through a central controller — reducing single points of failure. In DALI-1, only one master was specified; secondary controllers required workarounds.

Standardised device types and application controllers: IEC 62386 Part 200 onwards defines device types: Part 202 = self-contained emergency lighting, Part 207 = LED drivers, Part 208 = linear current regulators, Part 209 = load controllers, Part 210 = sequence controllers, Part 211-217 = colour control (DT-8). Before DALI-2, LED driver communication for colour tuning (warm/cool white, RGBW) was handled by proprietary extensions. Now, DT-8 (Device Type 8) standardises colour temperature (Tc), CIE xy chromaticity, RGBWAF six-channel and primary colour control — all interoperable between brands.

Mandatory certification: DALI-2 products must pass testing at an accredited lab and receive certification from the DALI Alliance before they can carry the DALI-2 logo. This eliminates the interoperability failures of DALI-1. A DALI-2 certified MDT gateway will correctly communicate with any DALI-2 certified Tridonic, Helvar, Osram or Panasonic driver.

What stayed the same

The DALI-2 physical layer is identical to DALI-1: 2-wire, polarity-insensitive, 1200 baud, 16V nominal bus voltage, maximum 64 ECGs per bus, maximum 64 groups, 16 scenes. Existing DALI-1 equipment can co-exist on a DALI-2 bus — DALI-2 controllers are backward compatible. The addressing commands (short address 0-63, group address 0-15, broadcast) are identical. Wiring practice: LSZH 2-core cable, unshielded, max 300m total cable length on one bus.

Practical impact for KNX projects

In KNX+DALI-2 projects: the MDT DALI Gateway DG-2 connects KNX TP to one DALI-2 bus. The gateway is itself a DALI-2 application controller — it receives KNX scene or group commands and translates to DALI-2 device commands. DT-8 colour control: KNX DPT 5.001 (0-100% warm/cool) → DALI-2 DT-8 Tc command → LED driver adjusts colour temperature. Emergency lighting: DALI-2 Part 202 ECGs report test results back to gateway → KNX group address updated → compliance report generated. The migration from DALI-1 to DALI-2 for most integrators is transparent — the DALI-2 gateway handles backward compatibility, and all new LED drivers purchased today should carry DALI-2 certification.