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D4i overview

D4i – the DALI standard for intelligent, IoT-ready luminaires

UPDATE (October 2020):  The DALI Alliance has started D4i certification of DALI-based control devices that are designed for mounting on LED luminaires. >> More details

D4i is the DALI standard for intelligent, IoT-ready luminaires.

By taking care of control and power requirements, D4i makes it much easier to mount sensors and communication devices on luminaires. In addition, intelligent D4i LED drivers inside the luminaire have the capability to store and report a wide range of luminaire, energy and diagnostics data in a standardized format.

Smart D4i luminaires are ideal platforms for the IoT, capable of gathering information from on-board D4i sensors, and providing data for performance monitoring, asset management, predictive maintenance and many other tasks. Communication and data exchange with an external network can take place via a D4i control device with wireless communication capabilities.

D4i is an extension of the DALI-2 certification program that brings standardization to small DALI networks inside luminaires. D4i LED drivers have a mandatory set of features related to power-supply requirements and smart-data capabilities. 

>> Specifications for D4i LED drivers

>> Specifications for D4i control devices

>> Find out how D4i is used in intra-luminaire DALI for outdoor



DiiA members are now able to certify their D4i LED drivers and control devices in a procedure that includes independent verification of test results.

>> More details on D4i certification

Certified products are eligible to carry the D4i logo trademark, which can also be used on qualifying luminaires.



D4i is aligned with the new ANSI C137.4 standard >> More details

D4i is also compatible with socketed connector systems such as NEMA/ANSI C136.41 and Zhaga Books 18 and 20.

DiiA and Zhaga are working closely together and have developed the joint Zhaga-D4i certification program for D4i luminaires that have Zhaga sockets which can accomodate D4i control devices.


D4i for LED drivers: Data and power

Data specifications

D4i enables intelligent luminaires by standardized the storage and reporting of data relating to the driver, light source and luminaire. The bi-directional nature of DALI enables such data to be communicated with the lighting-control network. Data stored within the driver can be used for enhanced asset tracking, as well as performance monitoring, diagnostics and energy metering.

The data specifications listed below are mandatory requirements for all D4i LED drivers. 

Data specifications D4i requirement
DALI Part 251 – Luminaire Data Mandatory
DALI Part 252 – Energy Data Mandatory
DALI Part 253 – Diagnostics Data Mandatory

>> More on DALI Data specifications

>> Download Data specifications from DiiA

Power-supply specifications

D4i also defines how a driver with an integrated DALI bus power supply can provide power to a connected DALI device on the bus. Within a single luminaire, this greatly simplifies the incorporation of DALI sensors or other control devices that are solely powered from the DALI bus.

For control devices with higher power requirements — such as wireless communication devices for city-wide networks — an auxiliary 24V power supply is also included in the D4i specifications.

Power-supply specifications D4i requirement
DALI Part 250 – Integrated Bus Power Supply Mandatory
DALI Part 150 AUX Power Supply Optional

>> Download Power-supply specifications from DiiA


D4i for control devices: DALI Part 351

DALI Part 351 is a specification for D4i control devices that can be inside or attached to a luminaire. D4i control devices are powered either from the DALI bus or from an AUX supply.

Part 351 defines four different classes of control device (types A-D), and includes specific requirements for power consumption. There is also a mechanism to decide which control device takes priority when more than one is present.

Types A-D cover both indoor and outdoor applications, and include devices such as wireless network lighting controllers (NLCs), photocells (light sensors), movement sensors and timers.

Control device specification D4i requirement
DALI Part 351 – Luminaire-mounted Control Devices Mandatory

>> Download Part 351

D4i presentation

>> Click to view


The D4i logo and D4i wordmark are trademarks in various countries in the exclusive use of DiiA. Use of these trademarks is restricted to DiiA members only. 

>> Download the DiiA Requirements document "D4i Certification and Trademark Use"

News & Links

NEWS: First D4i certified LED driver added to DiiA product database (Dec 2019)

PRESS RELEASE: DiiA starts D4i certification of LED drivers (Nov 2019)

NEWS: D4i specifications updated and new Part 351 published by DiiA (October 2019)

NEWS: ANSI C137.4-2019 standard aligns with D4i specifications (October 2019)

PRESS RELEASE: D4i brings standardization to intra-luminaire DALI (May 2019)




What is intra-luminaire DALI?
As the name suggests, intra-luminaire DALI refers to a DALI bus within an individual luminaire, connecting the LED driver(s) with any DALI-2 control devices. 

What is the difference between DALI-2 and D4i?
For LED drivers and control devices, D4i is an extension of DALI-2. D4i products are DALI-2 products that have a specific set of features. All D4i-certified drivers and control devices are also DALI-2 certified. Such products can optionally carry either the D4i logo or the DALI-2 logo, or both.

When will D4i certification be available?
D4i certification of LED drivers is available. Control devices will be added at a later date.

What data can be read out from a D4i driver?
Data related to asset management, energy usage, diagnostics and maintenance can be stored in and retrieved from the driver. Details can be found in the DiiA specifications—Parts 251 to 253.

What are the necessary criteria to achieve D4i certification?
LED drivers need to implement Part 207 and Parts 250-253. Part 150 is optional. In addition, the default state of the integrated bus power supply must be “on”. Products must also meet the requirements listed in "D4i Certification & Trademark Use" (download here)

Can the D4i logo be used on sensors?
Yes, the new D4i specification DALI Part 351 defines the D4i requirements for sensors and other control devices. D4i certification will be available at a later date.

How can I use multiple D4i luminaires in DALI systems?

To use multiple D4i luminaires together in the same DALI system, ensure the maximum bus power supply current of 250mA will not be exceeded. For example, a D4i luminaire with one driver may have a maximum bus power supply current of 60mA. Four such luminaires could be connected together on a DALI bus (the total maximum bus power supply current would be 240 mA). But if more than four luminaires are connected, then one or more of the bus power supplies will need to be disabled. For D4i drivers, this can be done using a programming tool before connecting the luminaire's DALI bus into the larger system.

D4i specifications for intra-luminaire DALI

The example below shows a two-node, outdoor-lighting application. Power available to both nodes, and the intra-luminaire DALI bus supports socketed systems. The intelligent luminaire has sensing capabiliites and can report data stored in the LED driver to the external network via the DALI bus and the wireless link.