Optoelectronics
DALI supports standardised wireless architectures for lighting control
Paul Drosihn, general manager of the DALI (Digital Addressable Lighting Interface) Alliance, outlines various methods for implementing interoperable control systems. These approaches aim to fully utilise the connectivity, bidirectionality, and lighting-specific data capabilities provided by the DALI protocol.
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ontemporary lighting technology has evolved compared to only a few years ago, featuring energy- saving LEDs and sophisticated control systems combined with sensors and IoT devices. This connected ecosystem creates opportunities for attractive, efficient lighting projects that can be controlled at the touch of a button or a smartphone’s screen, or even respond to the world around us.
Conventional lighting systems have been controlled using wired networks, but recently interest in wireless connectivity methods has increased. In fact, the global market for wireless smart lighting control systems is estimated to be around $6 billion, growing to nearly $19 billion by 2030, according to research firm Research and Markets. Wireless control systems can be easier and quicker to install due to less wiring needed — particularly in older building retrofits, which may set restrictions on where wires can run. Quicker installation translates into lower labour costs.
The lack of wires can also make a system more flexible and scalable, with the freedom to move luminaires and add new devices. Wireless lighting systems are typically organised in a mesh configuration, where each device or node is connected to multiple other nodes. This increases reliability, as there is no single point of failure, and control messages are automatically rerouted if one node fails. However, there are still scenarios where a wired solution is preferred or even may be mandated. In some circumstances, hybrid solutions may be desirable. Some technologies enable choice and keep future options open by enabling wired and wireless lighting-control networks to operate together.
24 June 2024
Interoperability with a standard protocol
Whether wired or wireless, a lighting control system requires each device to be capable of communicating with the others. Such interoperability can only be achieved with a suitable standard, which manufacturers all agree to follow.
In lighting control, the Digital Addressable Lighting Interface (DALI) is likely the most widely known open standardised protocol. It has been deployed in countless applications around the world over many years. Based on the open global standard IEC 62386, DALI is an established protocol for bidirectional digital communication between lighting control devices and sensors. DALI devices are individually addressable, so it fits well with other IoT systems.
DALI is managed by the DALI Alliance, an open consortium of lighting companies with more than 350 members globally. The alliance drives the growth of DALI-based solutions and operates the DALI-2 and D4i certification programs to ensure cross-vendor interoperability.
How DALI supports wireless lighting Typically, DALI uses a dedicated two-wire bus for communications between devices. However, more recent developments offer two alternative approaches to combining DALI lighting control and wireless connectivity: Standardised gateways between DALI and wireless ecosystems – starting with specifications for Bluetooth mesh and Zigbee from the Connectivity Standards Alliance (CSA).
DALI+, a new specification that supports using a wireless architecture instead of wires for a DALI system.
Both approaches have merits, and having Components in Electronics
Figure 1: Gateway (GW) between a non-DALI wireless ecosystem (Bluetooth mesh or Zigbee) and a DALI system.
two options gives designers the flexibility to choose the right control system for a specific application. A third option — the capability to combine wired and wireless devices in a system — further expands flexibility.
Wireless to DALI gateways Wireless to DALI gateways enable existing wired DALI devices to be used in a non-DALI wireless ecosystem. The gateways translate commands from the wireless side so the wireless ecosystem can control and query the DALI devices as if they were part of the wireless network.
Figure 1 shows how a gateway participates in the wireless ecosystem. The gateway contains a DALI application controller that connects to devices in the wired DALI network. The gateway architecture enables the wireless ecosystem to control and query DALI control gear, such as LED drivers, as if the DALI devices were part of the wireless network. DALI has specified two such gateways, with Bluetooth mesh and Zigbee as the wireless protocols, and other protocols may be supported in future. The DALI devices are automatically discovered and addressed by
the gateway before joining the ecosystem network. Security is ensured via the existing features of Bluetooth mesh or Zigbee as appropriate.
In operation, the wireless devices talk to the gateway using their existing protocol (Zigbee or Bluetooth). They can control light output and fading of DALI devices via the gateway, and they can read lamp failure information from the DALI devices, as well as selected data such as energy usage and diagnostics.
Note that application controllers in the DALI network cannot control, configure, or query devices in the wireless ecosystem. This means that the wireless ecosystem is effectively the primary control, and the DALI system is subordinate.
It might seem simpler to implement the entire network using Bluetooth mesh or Zigbee. However, one benefit of using the gateway specifications is that existing DALI products — especially LED drivers — can be used. The market has many DALI-2 and D4i certified products from a wide range of suppliers, providing choice and futureproofing. Another reason to base a lighting control
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