DALI dimmers are digital control, and require a separate digital controller (e.g. Leviton CD250-C), which can feed up to 64 of the DALI Drivers, and provide individual or group dimming control. It is easier to use than the older DMX standard
A DALI controller (plus a 16v 250mA CC supply) will connect to the DALI control bus of each DALI driver
The output of the DALI driver is then connected to the LED, typically 12V or 24V versions.
Digital Addressable Lighting Interface (DALI) is a trademark for network-based systems that control lighting in building automation. The underlying technology was established by a consortium of lighting equipment manufacturers as a successor for 0-10 V lighting control systems, and as an open standard.
DALI is specified by technical standards IEC 62386 and IEC 60929. Standards conformance ensures that equipment from different manufacturers will interoperate.
A DALI network consists of a controller and one or more slave devices (e.g., electrical ballasts, LED drivers and dimmers) that have DALI interfaces. The controller can monitor and control each device by means of a bi-directional data exchange. The DALI protocol permits devices to be individually addressed and it also allows multiple devices to be addressed simultaneously via multicast and broadcast messages.
Each device is assigned a unique static address in the numeric range 0 to 63, making possible up to 64 devices in a basic system. Addresses may be arbitrarily assigned and devices need not be mapped to contiguous addresses (gaps may exist in the address map). DALI gateways can be used to implement systems that have more than 64 devices. Data is transferred between controller and devices by means of an asynchronous, half-duplex, serial protocol over a two-wire bus, with a fixed data transfer rate of 1200 bit/s.
A single pair of wires comprise the bus used for communication to all devices on a DALI network. The network can be arranged in a bus or star topology, or a combination of these. DALI is not classified as SELV (Separated Extra Low Voltage) and therefore its wiring may be run next to mains cables or within a multi-core cable that includes mains power. Data is transmitted using manchester encoding and has a high signal to noise ratio which enables reliable communications in the presence of significant electrical noise.
DALI wires can be connected to a device without regard for polarity. Signal level are defined as 0±4.5 V for "0" and 16±6.5 V for "1". Central interface power maximum is 250 mA and 2 mAper unit. The network cable is required to be mains-rated, with 600 V isolation and at least a 1 mm cross-section, with a maximum drop of 2 volts along the cable (max 300 m). Signal interface is galvanically separated and doesn't need any termination resistors.
Each device on a DALI network can be individually addressed, unlike DSI and 0-10V devices. Consequently, DALI networks use fewer wires than DSI or 0-10V systems.
Some devices (e.g., HF ballasts) are mains powered, and only have functional isolation between the mains and the DALI control. This means that even though the DALI control cable operates at ELV potential, it must be treated as if it were at mains potential. A DALI network requires a 24V DC 250 mA power supply to operate. This voltage appears on the data cables and can be used to supply power to peripherals that require it, such as motion detectors. A separate power supply can be used, although some manufacturers provide DALI gateways with an integrated power supply.