Technical notes, queries & updates

What are device types? What is DT8? How does it relate to DT6?

What are DT numbers, and how do they relate to Part numbers?

Device type (DT) numbers originate from the IEC 62386 standard. They are only used for Parts relating to control gear (Parts 2xx) – there are no DT numbers for input devices and application controllers.

DT numbers were added when it became necessary to separate the different commands required for different lamp types.

The DT number relates to the IEC 62386 Part number as follows:

• [DT number] = [Part number] - 201

The most commonly-used DT numbers are:

What is DT8?

DT8 means “Device Type 8” and is associated with DALI colour control.

DT8 is defined in Part 209 of IEC 62386, which describes control gear that enable colour control.

DT8 is sometimes wrongly described as “DALI type 8” – there are no “DALI types”.

DT8 has also been wrongly described as “DALI-8” but DALI-8 does not exist. DALI-2 is the only example where DALI is used with a numerical extension.

How are DT numbers used?

The DT number is used to the respond to the command “QUERY DEVICE TYPE”. This allows an application controller to check the capability of control gear on the bus.

Control gear can implement multiple Parts, and therefore can have multiple DT numbers.

>> More on device type discovery

What’s the difference between DT6 and DT8?

Each device type has a specific set of features, and these are not overlapping or contradictory. DT6 has a set of features that can be used in all LED drivers, while the DT8 commands and features only relate to colour control.

An LED driver with colour control may implement both Parts 207 and 209, or it may implement Part 209 only (in both cases, Parts 101 and 102 are also implemented).

DT6 LED drivers use a single DALI short address to control a single output, for example to change the light-output level (following the standardized dimming curve) of a set of connected LEDs.

DT8 LED drivers can use a single DALI short address to control two or more outputs. This allows both the colour temperature and brightness of a fixture to be controlled by a single channel.

DT8 can help to reduce the number of drivers used in an application, the amount of wiring needed in the installation, and the number of DALI addresses used, which simplifies design and commissioning.