In 2019, the DALI Alliance launched D4i, a fresh version of the Digital Addressable Lighting Interface (DALI) standard for the internet of things (IoT) era. This version redefines intraluminaire communication and enables live, real-time data acquisition for measuring, monitoring and plug-and-play installation. As such, it offers a viable path to luminaire­-level control and lighting playing a part in the IoT.

DALI is a set of rules that defines how devices operate together. Recognized as an international standard since 2002, it ensures control actions are carried out in an accurate and repeatable manner, such as predictable, standardized dimming performance. It was introduced as a digital solution that offers consistent and flexible lighting control as a standardized alternative to 0–10V analog.

DALI’s history

DALI caught on in Europe, but its adoption was slower in the United States. This may be because in its early days, installation and commissioning could be time-consuming and costly, and addressing replacement ballasts could be difficult. Still, the technology and market continued to develop.

In 2017, the DALI Alliance, a consortium of lighting companies formed to grow the market for DALI systems, launched DALI-2, a product certification program. The program is based on the latest version of the protocol, which standardizes interoperability and control of LED drivers and sensors. All device types needed to build a lighting control system are represented. 

Certified products may display the DALI-2 logo, which indicates they provide specified functionality and are interoperable. The DALI Alliance website lists more than 3,000 DALI-2 certified products from more than 200 brands, including major U.S. brands.

How can it be used?

A DALI system involves connecting LED drivers (or ballasts) using digital low-voltage control wiring that may be installed as Class 1 or Class 2 in various wiring configurations. Up to 64 LED drivers and 64 sensors can be connected to the loop, and multiple loops can be combined into larger networks as needed to cover a building. Each connected device is assigned an address in the system, and the loop contains at least one DALI controller. Power and data are carried by the same pair of wires.

Using digital signals offers several advantages. It makes the system less prone to electrical noise interference and enables two-way communication for commands and data, allowing luminaires to generate data useful for measuring and monitoring. It transfers commissioning, zoning and rezoning to software by rendering control as independent of physical device calibration and lighting circuit wiring. Devices may be controlled individually or assigned to groups.

As lighting controls technology evolved toward digitalization, wireless communication and delivery of IoT strategies, so did DALI. In 2019, the DALI Alliance released D4i, technically an extension of DALI-2. Previously, DALI focused on communication between luminaires; D4i builds on this foundation by adding features focused on connecting LED drivers to sensors/wireless radios within the luminaire. Due to its utility, the U.S. Department of Energy launched an L-Prize competition centered around developing LED products based on D4i or ANSI C137.4 (harmonized with D4i), which is expected to spur innovation.

“D4i enables a standardized approach to luminaire-level lighting control by simplifying the addition of communication devices and sensors to luminaires,” said Paul Drosihn, general manager, DALI Alliance. “D4i includes mandatory features such as the availability of a rich set of data for energy usage reporting, diagnostics and maintenance and luminaire information. Crucially, D4i also specifies power requirements that enable plug-and-play connectivity of luminaires, network lighting controllers and sensors, especially when used in conjunction with a connector system such as Zhaga or ANSI C136.41.”

A mandatory D4i requirement is the ability for drivers to store luminaire information such as power, light distribution and more. This information can be added to the driver during the manufacturing process and can be extracted for automatic commissioning and ongoing asset management and maintenance. In the field, the driver can generate real-time energy consumption data and diagnostics, which can be used to fine-tune energy-saving strategies, quantify energy savings and maintain the system. A connected device can report a failure or answer a query about its status or other information.

Drosihn said D4i is designed to further allow wireless communication devices to be easily connected to D4i-enabled luminaires. Communication and control inside the luminaire use the DALI protocol while the luminaire operates externally within a non-DALI network. Soon, the DALI Alliance will introduce DALI-2 certification for standardized wireless-to-DALI gateways, which will allow a D4i luminaire or wired DALI-2 luminaire network to be controlled by a wireless ecosystem using protocols such as Bluetooth mesh and Zigbee.

D4i brings DALI into the IoT era and offers a standardization path for networked lighting control. Learn more about D4i at the DALI Alliance website at DALI-Alliance.org.

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