PART 1
What is a DALI lighting control system?
DALI, standing for Digital Addressable Lighting Interface, is an international standard communication protocol and a global standard for dimming. It is an open protocol, jointly proposed by a number of international lighting manufacturers, which means that all components of a lighting system marked with the DALI logo, even from different manufacturers, can work with one another.
At present, the DALI Alliance covers nearly 160 lighting companies worldwide. DALI is currently the most advanced lighting control system in which the brightness of each light can be smoothly adjusted in the range of 0-100%. Besides, it offers dynamic creation of groups, ability to configure and reconfigure for changing scenarios, monitoring of energy consumption and luminaire conditions, etc.
DALI uses a master-slave structure, including a bus power supply unit, some masters and a few slave devices.
1. Master, is generally the DALI controller, switch panel and sensors. The common feature is that they can actively send out DALI signals. As the name suggests, they are master to give commands in the system.
2. Slaves, are generally DALI ballasts, drivers and relays. They can not actively send out DALI commands, but only receive DALI commands first, if there is a request for an answer, then they start to send out the response data. They play the slave role to carry out the commands in the system.
3. Bus power supplies provide typically 16 V and up to 250 mA to provide power to devices connected to the bus. Each component connected to the interface may consume a maximum of 2 mA.
PART 2
Advantages of the DALI System
1. Grouping and precise control of multi-scene: In DALI system, each DALI LED driver plus each dimmable lamp is assigned a unique address so they can be operated individually. This also makes it possible that each DALI device can be assigned membership to a group or multiple groups according to changing scenarios. Such flexibility allows users to design and adjust their lighting schemes as they need.
2. High noise immunity: The DALI system is based on digital signals making it less liable to interference, even if the control wires are run in the same conduit as the line voltage wires. DALI systems are bi-directional, allowing control systems not only to give commands but also to query data devices and obtain information about the status of each device, such as status of the power driver, fault information and current brightness values.
3. Simple and easy to design: devices only need to be connected to each other via the digital signal interface, and connected to the 2-core control cable in parallel. Once the cable connection is complete, all the groupings and scenes can be programmed by computer software during installation and commissioning, as well as design modification, re-layout and separation, without re-wiring. As a result, the DALI lighting system has a very simple but flexible wiring system.
4. Simple and economical installation: DALI is most commonly wired with a multi-core cable that also carries mains power. Typical cables would be either 5-core (live, earth, neutral, DA, DA) or 6-core (live, emergency live, earth, neutral, DA, DA). Because of lack of extra circuit controls, it is much simpler to install than other systems. The system can have both negatively and positively polarized wires. However, the control gears are free from polarity to ensure indifferent connectivity. No shielded cables are required and the DALI system can be routed without problems with standard cables.
It should be noted that when the current on the control line is 250mA and the line length is 300 meters(at a wire cross-section of 1.5 mm2), make sure the voltage drop does not exceed 2V. DALI cables can be wired next to normal mains carrying wires reducing the need to segregate the control wires or special control cabinet.
5. Simple and reliable communication structure: the use of Manchester coding avoid false codes. Transmission rate of 1200 baud can ensure that the communication between devices is not interfered.
6. Wide range of use: DALI is no longer limited to ballasts. LEDs also adopt DALI dimming. Control devices such as radio receivers, relay switch input interface; and all kinds of button panels, as well as LED display panels, have already adopted DALI, which will make the application of DALI more and more extensive. The size of controllers expand from the smallest office to the volume of several rooms.
The development of smart technology has not only changed the way lamps are controlled, but also spawned a new industry: smart lighting. It used to be a simple on and off control, and now, in accordance with people’s living habits or time table, the lighting can be automatically adjusted to provide a comfortable, healthy, and energy-saving light environment which is suitable for the current life and work scenes.
