The communication system is helping with smarter cities in the U.S.
Digital Addressable Lighting Interface (DALI) is a wired communication system for control of lighting systems. DALI has been around since the 1990s and is the now the most widely used dimming control system for interior lighting in Europe and many other parts of the world.
DALI hasn’t been a strong contender in the U.S. for interior lighting, but now it finds new growth in an outdoor lighting niche.
What is DALI?
DALI was created as a means to digitally control and dim ballasts in fluorescent lighting fixtures using a simple two-wire connection that can be wired as a daisy chain using inexpensive wire and, in many cases, can utilize the same conduits as the main electrical wiring. This makes wiring a DALI system easy and well suited for installation by electricians.
DALI is “addressable,” allowing it to control individual fixtures as well as groups of fixtures easily. It was designed for a single control or “master” to control up to 64 lighting fixtures in a single DALI bus or “loop.”
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DALI-2 was launched in 2014, allowing as many as 64 controls plus the 64 fixtures to be on the same loop. At the same time, support was added for many different types of controls and fixtures, including LED drivers, emergency lighting and white light tunable and color changing fixtures.
DALI allows for two-way communication, meaning that it can precisely control many aspects of a lighting fixture as well as read back the operational status such as light level, lamp life, failures, configuration and emergency lighting battery tests. DALI use continues to grow overseas as the main choice for LED lighting control.
The standard for the DALI Protocol is managed by the International Electrotechnical Commission (IEC) through the IEC 62386 family of standards. The DALI trademark, promotion, licensing and compatibility testing is controlled by the Digital Illumination Interface Alliance (DiiA), insuring the interoperability of all products using DALI.
The evolution of DALI is rapidly increasing as more uses are found for this simple and reliable protocol. Recent work on further expansion of the DALI protocol will allow control of:
- Demand responsive lighting systems
- Reading fixture energy usage
- Updating the device software over the DALI wires
Standards are also are in process that will allow DALI over wireless and Ethernet connections, bringing DALI to Internet of Things applications in the future.
While it is easy to install and wire, the programming and commissioning of a large DALI system requires specially trained personnel and software tools. With the power and flexibility of DALI comes some complexity and not enough installations have taken place in the U.S. to encourage installers to develop needed skills, or for U.S.-based lighting and control manufacturers to develop the diverse products that are currently available overseas.
New DALI Applications for Smarter Cities
With the growth of smart cities, the ubiquitous street lighting pole is being eyed by utilities and municipalities for a key part of the digital infrastructure. Huge energy savings can come to fruition with the use of advanced lighting control sensors in outdoor lighting fixtures.
Technology experts envision plans to task lighting poles for applications beyond lighting, providing weather information as well as using cameras, visibility sensors, gunshot detectors and digital signage for traffic and security uses.
The Southern Company (Alabama Power, Georgia Power, Gulf Power and Mississippi Power) has been working with the DALI protocol for the last few years to provide a digital control data bus inside their roadway lighting poles to connect different sensors and LED drivers in an interoperable manner. A wireless network lighting control (NLC) node on the pole can then communicate with multiple LED drivers and sensors within the pole using DALI.
The ability for DALI to provide precise digital control and feedback status information, such as lamp failures, is a huge advantage for this architecture. The simplicity of the DALI wiring is a perfect match for application within these poles. Field commissioning and programming is non-existent since the DALI drivers and controls have a defined purpose and come pre-programmed from the factory.
The Southern Company has gone a step further and reaped additional benefits by storing detailed data about all aspects of the lighting pole and luminaire in the internal LED driver. It then uses DALI to transfer the data via the NLC into the company’s central management system without human intervention. This increases the crew productivity greatly and reduces data entry errors to zero.
When the luminaires are ordered, the participating manufacturer encodes all details about the manufacturer name, part number, style, wattage, source, lumens, color temperature, distribution type, the color of luminaire and voltage by using the existing scene storage mechanism built into DALI.
So far, Southern Company has installed about 650,000 outdoor LED luminaires with DALI .
“DALI is a digital lighting protocol that supports bi-directional communications — something not supported by the previous 0-10 volt control systems,” notes Kevin Fitzmaurice, lead product engineer for Southern Company. “DALI allows our LED luminaires to automatically commission themselves into our lighting central management system without human assistance via our wireless networked lighting control system. This is one of the many advantages of using DALI instead of the 0-10 volt lighting protocol.”
DALI’s Broadening Reach in the U.S.
Fitzmaurice saw a need to standardize this idea to make it easy for other organizations to implement, so he approached the recently formed U.S. standards committee for lighting systems, ANSI C137, to see if this was a project of interest. C137 started work on the standard with cooperation from the DiiA and the IEC DALI standards committee.
The C137 committee is now working on standardizing memory bank locations within a DALI driver to store the needed information as well as providing energy usage information. The need for a common DC power supply to power the sensors was seen as a key piece to supply power to all types of sensors within the luminaire. The result will be a standardized way of using DALI for communicating within a smart lighting pole to include advanced control, sensing, monitoring and detailed asset management.
Ronald Tol, technical and certification work group chair with DiiA, says, “The DiiA is working with ANSI, Zhaga and the IEC to enable DALI as an intra-luminaire communication bus for smart city applications. There are multiple benefits when open standards are used in these types of applications.
On topic: Importance of Emergency and Exit Lighting in Your Building
“The standardized DALI bus power supply and auxiliary power supply integrated in a DALI-2 LED driver provide the required power to a communication and/or sensor node in a Zhaga or NEMA socket on a luminaire. This significantly simplifies the installation for luminaire manufacturers at a lower integral system cost. Furthermore, luminaire asset data, energy data and diagnostics information in a standardized format delivers on the promise of true interoperability of communication and/or sensor nodes, DALI-2 LED drivers and luminaires implementing the standard.”
Other Future Uses
This new ANSI C137 standard for DALI memory banks and auxiliary power supply may also cross over to parking lot and interior lighting applications and help boost the deployment of DALI networks in the U.S.
The interior space is currently weighing the options of many different open wireless digital control protocols, and proprietary wired systems are still widely deployed domestically. However, DALI is currently the only wired digital system that’s a standardized open protocol specifically designed for controlling general lighting.
Robert Hick of RH Controls Consulting LLC, recently retired as vice president of engineering for Leviton’s Energy Management, Control and Automation business unit after 18 years.
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