DALI was developed by all the leading Electronic Control Gear manufacturers who came together to define the functions of a DALI-ECG and a load conforming to DALI within a lighting system.
DALI was created in the form of an industry standard in order to satisfy all the demands placed on modern lighting controls.
Above all, it includes a facility for receiving feedback from the ECGs concerning their current state and also for storing certain scenario values in an ECG. Every DALI-ECG configuration is able to store 16 group constellations and 16 scenarios.
DALI product features
More information is available at www.dali-ag.org.
The DALI AG, part of ZVEI of Germany, has created the open Digital Addressable Lighting Interface standard (DALI). It is laid down in the global IEC document 60929 as an Open standard.
DALI is supported by a great variety of manufacturers and suppliers of luminaires and ballasts. These are connected in various forms:
The DALI-protocol is well accepted in the lighting market for fluorescent, High Intensity Discharge lamp applications, Solid State Lighting (LED) and Incandescent systems. Any mixture of DALI compliant products can be included within a DALI system.
Additional standardization documents containing protocol extensions are in specification status for:
Full compatibility of all ballasts and luminaires manufactured with the DALI protocol
Interchangeability of ballasts and luminaires in existing installations.
DALI is specified for:
Main DALI features and benefits compared to 1-10V analogue control systems
Main differences between DALI and building automation buses:
DALI is not competing against BMS systems, it is only complementing them through an interface.
Research work connected to the DALI project began midway through the 1990s. However, the development of commercial applications got under way a little later, in the summer of 1998. At that time, DALI went under the name DBI (Digital Ballast Interface). An interface device (or ballast) is an electronic inductor enabling control of fluorescent lamps.
In addition to the work done at Helvar, the DALI standard has been
the subject of R&D by other European ballast manufacturers such
as Hüco, Philips, Osram, Tridonic, Trilux and Vossloh-Schwabe. The
DALI standard will be added to the European electronic ballast
standard EN60929 Annex E
.
Different manufacturers’ products can be interconnected provided that the manufacturers adhere to the DALI standard. This standard embodies addressability, i.e. ballasts can be controlled individually when necessary. Previously, ballasts connected to an analogue 1-10 VDC low-voltage control bus have been subject to simultaneous control. Another advantage enabled by the DALI standard is communicating the status of ballasts back to the control unit. This is especially useful in extensive installations where the light fixtures are widely distributed. The execution of commands compliant with the DALI standard and obtaining the status data presuppose intelligence on part of the ballast. This is provided by mounting a microprocessor within the ballast; the microprocessor also carries out other control tasks. The first products based on the DALI technology became commercially available at the end of 1999.
DALI messages comply with the Bi-Phase, or Manchester, coding in which
the bit values 1
and 0
are presented as two different
voltage levels. The change-over from the logic level UNTRUE
to
TRUE
corresponds to bit value 1
, and the change-over from
the logic level TRUE
to UNTRUE
corresponds to the bit value
0
. The coding includes error detection and enables power supply
to the control units also when there are no messages being transmitted
or when the same bit value is repeated several times in succession. The
bus’s forward frame (from the control unit to the ballast) is
comprised of 1 START bit, 8 address bits, 8 data/command bits, and 2
STOP bits. The backward frame (from the ballast to the control unit)
is comprised of 1 START bit, 8 data bits and 2 STOP bits. The baud rate
is 2400.
DALI messages consist of an address part and a command part. The address
part determines which DALI module the message is intended for. All the
modules execute commands with broadcast
addresses. Sixty-four
unique addresses are available plus sixteen group addresses. A
particular module can belong to more than one group at the one time.
The light level is defined in DALI messages using an 8-bit number.
The value 0
(zero) means that the lamp is not lit. The DALI
standard determines the light levels so that they comply with the
logarithmic regulation curve in which case the human eye observes
that the light changes in a linear fashion. All DALI ballasts and
controllers adhere to the same logarithmic curve irrespective of
their absolute minimum level. The DALI standard determines the
light levels over a range of 0.1% to 100%. Level 1 in the DALI
standard corresponds to a light level of 0.1%.
The idea concerning the DALI protocol emerged when the leading
manufacturers of ballasts for fluorescent lamps collaborated in
the development of a protocol with the leading principle of
bringing the advantages of digital control to be within the
reach of as many users as possible. Furthermore, the purpose
was to support the idea of open architecture
so that any
manufacturer’s devices could be interconnected in a system.
The precondition to this was for the manufacturers to commit
themselves to the DALI standard.
In addition to control, the digital protocol enables feedback information to be obtained from the lighting fixture as to its adjustment level and the condition of the lamp and its ballast.
Examples of typical applications for the new system are office and conference facilities, classrooms and facilities requiring flexibility in lighting adjustment. The lighting-control segment based on DALI technology consists of maximum 64 individual addresses which are interconnected by a paired cable. DALI technology enables cost-effective implementation of lighting control of both smart individual lighting fixtures as well as of numerous segments connected to the automation bus of a building.