DALI-2 Device Types Explained: From DT6 to DT8 and Beyond

The DALI protocol identifies what a device does through a device type, a number that tells the master controller which standardized commands apply. This mechanism is what lets a single two-wire bus carry drivers, switches, and sensors from different manufacturers while remaining fully interoperable. For anyone specifying DALI-2 gear, the device type is a more meaningful specifier than the brand name.

The device types are defined in the 200-series parts of IEC 62386, one part per technology. Part 201 covers fluorescent lamp control gear as Device Type 0. Part 202 defines self-contained emergency lighting as Device Type 1, which is why emergency drivers can report battery and test status in a standardized way. Part 207 defines LED modules, the most important type for modern lighting, as Device Type 6, usually written DT6. Part 208 covers switching functions as DT7, and Part 209 covers colour control as DT8. Additional parts address discharge lamps, low-voltage halogen lamps, incandescent dimmers, and DC-powered control gear, each with its own device type number.

DT6 is the baseline for LED dimming. A DT6 driver accepts the standard DALI-2 arc power commands, from 0.1 to 100 percent in 254 logarithmic levels, and reports status such as lamp failure and power-on state. Any DALI-2 master that supports the LED device type can dim a DT6 driver, regardless of who manufactured it. For constant-voltage drivers, DT6 is the default device type and covers single-channel dimming of LED strips and linear fixtures.

DT8 extends DT6 with colour control and is defined in Part 209. It supports several colour types: Tc for tunable white, based on correlated colour temperature in mirek units; xy for CIE colour coordinate control; and RGBWAF for multichannel colour mixing. A DT8 driver controls two or more output channels under a single DALI address, which is why a tunable-white constant-voltage driver can adjust brightness and colour temperature together without consuming multiple addresses. For projects where colour tuning matters, confirming that the driver implements DT8 with the correct colour type is essential.

Device type interacts with the addressing model. A single device reports one device type, but a DT8 device internally manages multiple channels, sometimes called instances or primary channels, within that one address. This is different from using two separate DT6 drivers, which would occupy two addresses and require the controller to coordinate both. The choice affects both address budget and commissioning effort.

For specifiers, the practical checks are straightforward. Verify that the driver declares the device type you expect, DT6 for single-channel dimming or DT8 for colour control, and that the declaration matches a certified DALI-2 product. Be aware that a driver may support both DT6 and DT8 behaviour, and that the colour type, Tc versus xy versus RGBWAF, determines what the control system can actually do with it.

The device type system is one of the quiet strengths of DALI-2. It turns the vague promise of interoperability into a concrete, testable claim: a certified DT6 driver will respond to DT6 commands from any certified master. When a project mixes drivers from several brands, checking that every device type is certified and declared prevents the most common class of compatibility surprises during commissioning.