Digital Addressable Lighting Interface: Difference between revisions

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{{Use dmy dates|date=May 2019}}

{{primary sources|date=February 2012}}

[[File:Dali laitteet.jpg|thumb|right|DALI equipment is common for network-based lighting systems]]

{{Infobox protocol

| name = Protocol

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{{Infobox connector

| name = Connector

| type = [[lighting]] control

| image =

| logo =

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| manufacturer =

| production_date =

| superseded = 1-10 V/[[0-10 V lighting control]]|{{nowrap|0–10 V}} lighting control]]

| superseded_by =

| superseded_by_date =

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| pin1 =

| pin1_name = DA (or DA+)

| pin2 =

| pin2_name = DA (or DA-DA−)

}}

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==Technical overview==

A DALI network consists of at least one application controller and bus power supply (which may be built into any of the products) as well as input devices (e.g. sensors and push-buttons), control gear (e.g., [[electrical ballast]]s, LED drivers and [[dimmer]]s) with DALI interfaces. Application controllers can control, configure or query each device by means of a bi-directional data exchange. Unlike [[DMX512|DMX]], multiple controllers can co-exist on the bus. The DALI protocol permits addressing devices individually, in groups or via broadcast.<ref>{{Cite web|url=https://www.digitalilluminationinterface.org/dali/|title = Standards - Digital Illumination Interface Alliance}}</ref> Scenes can be stored in the devices, for recall on an individual, group or broadcast basis. Groups and scenes are used to insureensure simultaneous execution of level changes, since each packet requires about 25 ms - or 1.5 seconds if all 64 addresses were to change level.

Each device is assigned a unique short address between 0 and 63, making up to 64 devices possible in a basic system. Address assignment is performed over the bus using a "commissioning" protocol built into the DALI controller, usually after all hardware is installed, or successively as devices are added. The Device Address is commonly a LED driver with one or many LEDs sharing the same level. A DT6 driver is for single color temperature applications, a DT8 driver is used for CCT color tuning, or RGBWW multi color applications - for example a strip where all the "pixels" have the same color.

Data is transferred between devices by means of an asynchronous, half-duplex, serial protocol over a two-wire bus with a fixed data transfer rate of {{nowrap|1200 [[Bit rate|bit/s]]}}. Collision detection is used to allow multiple transmitters on the bus.

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The speed is kept low so no [[Electrical termination|termination resistors]] are required,<ref name=da>{{cite web |url=http://www.dali-ag.org/c/manual_gb.pdf |title=Digital Addressable Lighting Interface |publisher=DALI AG, Activity Group, ZVEI-Division Luminaires |website=DALI |date=September 2001 |access-date=12 July 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130627012349/http://www.dali-ag.org/c/manual_gb.pdf |archive-date=27 June 2013 }}</ref>{{Rp|21}} and data is transmitted using relatively high voltages ({{val|0|4.5|u=V}} for low and {{val|16|6.5|u=V}} for high{{r|da|p=19}}) enabling reliable communications in the presence of significant electrical noise. (This also allows plenty of headroom for a bridge rectifier in each slave.)

Each bit is sent using [[Differential Manchester encoding|Manchester encoding]] (a "1" bit is low for the first half of the bit time, and high for the second, while "0" is the reverse), so that power is present for half of each bit. When the bus is idle, the voltage level is continuously high (which is not the same as a data bit). Frames begin with a "1" [[start bit]], then 8 to 32 data bits inwith msbit-firstthe ordermost significant bit first (standard [[RS-232]] ishas the least significant bit lsbit-first), followed by a minimum of 2.45&nbsp;ms of idle.

==Device addressing==

A DALI device, such as ana LED driver, can be controlled individually via its short address. Additionally, each DALI device may be members of one to 16 groups, or be a member of up to 16 scenes. All devices of a group respond to the commands addressed to the group. For example, a room with 4 ballasts can be changed from off to on in three common ways:

===Single device===

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This method has the advantage of being immune to synchronization effects as described above.

This method has the disadvantage of requiring each ballast to be programmed once, by a DALI master, with the required group numbers and scene information. The fade time can still be configured on the fly, if required.

===Broadcast===

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

* DALI Broadcast go to 50%

==Scenes==

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==System Fail brightness==

A "system failure" level can be triggered by a loss of power (sustained low level) on the DALI bus, to provide a safe fallback if control is lost, a level of 255 excludes the device from this feature.

===Broadcast===

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

* DALI Broadcast go to 50%

==Brightness control==

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This is designed to match [[Human eye#Dynamic range|human eye sensitivity]] so that perceived brightness steps are uniform, and to ensure corresponding brightness levels in units from different manufacturers.{{r|da|p=21}}

==Commands for control gear==

Forward frames sent to control gear are 16 bits long, comprising an address byte followed by an opcode byte. The address byte specifies a target device or a ''special command'' addressed to all devices.

Except for special commands, when addressing a device, the 7 most significant bits is the device address. The least significant bit of the address byte specifies the interpretation of the opcode byte, with "0" meaning that the opcode is a light level ( ARC ) , and "1" meaning that the opcode is a command.

Multi packet commands are used for more complex tasks - like setting RGB colors. These commands use three "data transfer registers" (DTR, DTR1, DTR2 ) which can be read and written or used as a parameter by subsequent commands. For example, copy the current ARC level to DTR, save DTR as a scene. Evidently, the DTR value can be different in different devices.

Address byte (AB) format:

* <code>0AAA AAAS</code>: Target device 0 ≤ A < 64.

* <code>100A AAAS</code>: Target group 0 ≤ A < 16. Each control gear may be a member of any or all groups.

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* <code>1100 1100 to 1111 1011</code>: Reserved

Common control gear commands:<ref>[https://webstore.iec.ch/searchform&q=62386-102 IEC 62386-102]</ref><ref>{{Cite web|url=http://www.rayzig.com/manual/rayzig.html?112DALIcommands.html|title=Rayzig version 2.207|access-date=13 November 2020|archive-date=13 November 2020|archive-url=https://web.archive.org/web/20201113182940/http://www.rayzig.com/manual/rayzig.html?112DALIcommands.html|url-status=dead}}</ref><ref>https://www.nxp.com/files-static/microcontrollers/doc/ref_manual/DRM004.pdf {{Webarchive|url=https://web.archive.org/web/20201113152849/https://www.nxp.com/files-static/microcontrollers/doc/ref_manual/DRM004.pdf |date=13 November 2020 }} {{Bare URL PDF|date=March 2022}}</ref>

{| class="wikitable collapsible sortable"

! Value (Hex) !!Command !! Description !! Answer

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| ||'''Control commands''' || ||

|-

| XXAB || DAPC (level) || Sets targetLevel (0-255254) to device(s) at address AB using the current fade time, or stops a running fade (255). <span style="color:red">[S bit must be 0]</span>||

|-

| 00 || OFF || Set targetLevel to 0 without fading||

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==Emergency lighting==

IEC 62386-202 describes self-contained emergency lighting. Features include automated triggering of function tests and duration tests, and recording of results. These devices are currently included in DALI version-1 registration, with tests for DALI-2 certification in development. Such DALI version-1 products can be mixed with DALI-2 products in the same system, with no problems expected.<ref>{{cite web|url=https://www.digitalilluminationinterface.org/dali/comparison.html|title=DALI-2 versus DALI version-1|year=2018|website=DiiA Website|publisher=DiiA|access-date=4 March 2020|archive-date=2 March 2020|archive-url=https://web.archive.org/web/20200302132004/https://www.digitalilluminationinterface.org/dali/comparison.html|url-status=dead}}</ref>

==Wireless==