Digital Addressable Lighting Interface

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Protocol
International standard IEC 60929 and IEC 62386
Developed by Activity Group DALI
Introduced Early 1990s
Industry lighting
Connector
Type lighting control
Superseded 0-10 V lighting control
Hot pluggable Yes
External Yes
Cable mains-rated, with 600 V isolation, separate or part of power cable
Pins 2
Connector 1
Signal 16V DC
Max. voltage 22V DC
Max. current 250mA
Width 30bit/s
Bitrate 1200bit/s
Protocol asynchronous, half-duplex, serial protocol over a two-wire bus
Pin 1 +DALI bus
Pin 2 -DALI bus

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 alternative to Digital Signal Interface (DSI), on which it is based.

DALI is specified by technical standards IEC 62386 and IEC 60929. Standards conformance ensures that equipment from different manufacturers will interoperate. The DALI trademark is allowed on devices that comply with the current standards when manufactured. Members of the AG DALI (founded by Philips lighting in 1984) are freely allowed to use the DALI trademark; non-members can apply for a fee-bearing license.

Technical overview[edit]

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 addresses simultaneously via multicast and broadcast messages.[1]

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".[2] Central interface power maximum is 250 mA and 2 mA per unit.[2] 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).[2] Signal interface is galvanically separated and doesn't need any termination resistors.[2]

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.

Device addressing[edit]

A DALI device, such as a HF fluorescent ballast, can be controlled individually via its short address. In addition to this method of control, DALI devices can be arranged into groups in which all devices of the same Group can interact with each other. For example, a room with 4 ballasts can be changed from off to on in three common ways:

Single device[edit]

Using the Short Address, e.g. sending the following DALI messages:

  • DALI Short Address 1 go to 100%
  • DALI Short Address 2 go to 100%
  • DALI Short Address 3 go to 100%
  • DALI Short Address 4 go to 100%

This method has the advantage of not relying on the limited number of scenes available in each ballast, or having programmed each ballast with the required group numbers and scene information. The fade rate of the transition can be chosen on the fly. This method can have an undesirable side effect called "Mexican Wave" when a single large room such as an auditorium contains many ballasts, due to network latency of the comparatively slow 1200 baud rate of DALI. For example, a transition from all on to all off may result in a visible delay between the first and last ballasts switching off. This issue is normally not a problem in rooms with smaller numbers of ballasts.

Device groups[edit]

Using the DALI Group previously defined for the ballasts in the room, e.g.:

  • DALI Group address 1 go to 100%

This method has the advantage of being immune to the “Mexican Wave” effect as described above. This method has the disadvantage of requiring each ballast to be programmed with the required group numbers and scene information, and has a fixed fade rate which is pre set at the time of commissioning.

Broadcast[edit]

Using the DALI Broadcast command all, every ballasts will change to that level, e.g.:

  • DALI Broadcast go to 50%

Brightness control[edit]

The DALI protocol provides 254 levels of brightness between off and 100%. The brightness is translated to a ballast power level via a logarithmic dimming curve that matches eye sensitivity so that perceived brightness steps will have uniform brightness change, and to achieve a uniform brightness between units from different manufacturers.[2]

Commands[edit]

Common commands specified by the DALI standard:[3] [4] [5]

Command Addressing Mode Details Read\Write
Set Value Broadcast / Groups / Channels Send direct level values R/W
Off Broadcast / Groups / Channels Send the off command R/W
Up Broadcast / Groups / Channels Increase value by 1 until Max Level, honouring the fade time W
Down Broadcast / Groups / Channels Decrease value by 1 until Min Level, honouring the fade time W
Step Up Broadcast / Groups / Channels Increase value by 1 until Max Level, ignoring the fade time W
Step Down Broadcast / Groups / Channels Decrease value by 1 until Min Level, ignoring the fade time W
Recall Max Level Broadcast / Groups / Channels Output Max Value R/W
Recall Min Level Broadcast / Groups / Channels Output Min Value R/W
Step Down and Off Broadcast / Groups / Channels Decrease value by 1 /Turn off W
On and Step Up Broadcast / Groups / Channels Turn on / Increase by 1 W
Go to Scene x Broadcast / Groups / Channels Go to scene 1 - 16 W
Status Channels "OK, Ballast"
"OK, Lamp Failure"
"Off, Lamp Power On"
"Off, Limit Error"
"Terminate Fading"
"No, Reset State"
"Missing Short Address"
"Power Failure"
R
Device Channels Status of the Device R
Lamp Power On Channels Is the Lamp on? R
Version Number Channels Replies: Current Version R
Device Type Channels Replies with the device type R
Actual Level Channels Query Current Level R
Max Level Channels The Max level the Device can go to R/W
Min Level Channels The Min level the Device can go to R/W
Power On Level Channels Lamp output with voltage recovery R/W
System Failure Level Channels Lamp output in the event of system malfunction (e.g., interrupted DALI line) R/W
Scene Levels Channels Sets the leveles for Scene. R/W
Fade time Channels Time in seconds for fading from the current brightness value to the new brightness value R/W
Fade rate Channels Fade steps per second that are performed in response to an indirect fade command (Up and Down commands) R/W

Wireless extension[edit]

A wireless extension to DALI is available that enables DALI networks to communicate via wireless, radio frequency communication.[6]

See also[edit]

References[edit]

  1. ^ "Communication in building automation". Siemens Building Technologies. Siemens Building Technologies. 2013. Retrieved 12 July 2013. 
  2. ^ a b c d e "Digital Addressable Lighting Interface" (PDF). DALI. DALI AG, Activity Group, ZVEI-Division Luminaires. September 2001. Archived from dali-ag.org the original Check |url= value (help) (PDF) on 27 June 2013. Retrieved 12 July 2013. 
  3. ^ Artistic Licence. "The DALI Guide" (PDF). Artistic Licence. Retrieved 1 March 2016. 
  4. ^ Wago. "DALI/DSI Master Module 750-641 manual" (PDF). Wago. Wago. Retrieved 1 March 2016. 
  5. ^ "WAGO-Software WAGO DALI Configurator" (PDF). Wago. Wago. Retrieved 1 March 2016. 
  6. ^ "Wireless extension for DALI". Virtual Extension. Virtual Extension. 2014. Retrieved 3 August 2014. 

External links[edit]