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| superseded = 1-10 V/[[0-10 V lighting control]]|{{nowrap|0–10 V}} lighting control]]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 ensure 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 control gear devices and 64 control 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. Data The Device Address is transferredcommonly betweena devicesLED driver with one or many LEDs sharing the same level. A DT6 driver is byfor meanssingle ofcolor antemperature asynchronousapplications, half-duplexa DT8 driver is used for CCT color tuning, serialor protocolRGBWW overmulti acolor applications two-wire busfor withexample a fixedstrip datawhere transferall ratethe of"pixels" {{nowrap|1200have the [[Bitsame rate|bit/s]]}}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.

A single pair of wires comprises the [[Bus (computing)|bus]] used for communication on a DALI network. The network can be arranged in bus or star [[network topology|topology]], or a combination of these. Each device on a DALI network can be addressed individually, unlike DSI and 0–10V devices. Consequently, DALI networks typically use fewer wires than DSI or 0–10V systems.

The bus is used for both signal and bus power. A power supply provides a current limited source of up to 250&nbsp;mA at typically 16&nbsp;V DC; each device may draw up to 2&nbsp;mA unless bus-powered.{{r|da|p=20,35}} While many devices are mains-powered (line-powered), low-power devices such as motion detectors may be powered directly from the DALI bus. Each device has a [[bridge rectifier]] on its input so it is polarity-insensitive. The bus is a [[wired-AND]] configuration where signals are sent by briefly shorting the bus to a low voltage level. (The power supply is required to tolerate this, limiting the current to 250&nbsp;mA.)

Although the DALI control cable operates at [[Extra-low voltage|ELV]] potential, it is not classified as [[SELV]] (''Safety'' Extra Low Voltage) and must be treated as if it has only basic insulation from mains. This has the disadvantage that the network cable is required to be mains-rated, but has the advantage that it may be run next to mains cables or within a multi-core cable which includes mains power. Also, mains-powered devices (e.g., LED drivers) need only provide [[Insulation system#Categories of insulation|functional insulation]] between the mains and the DALI control wires.

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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 devicesdevice may be arrangedmembers intoof one to 16 groups, inor whichbe alla devicesmember of theup sameto group16 canscenes. 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 not requiring programming of group and scene information for each ballast. The fade time of the transition can be chosen on the fly.

ThisIf methoda maylarge benumber undesirableof becausedevices simultaneousneed controlto ofchange aat largeonce, numbernote ofthat devicesonly may40 notcommands beper possiblesecond dueare topossible network- latencytherefore, and64 theindividual comparativelyaddresses slowwould 1200require baud rate of1.5 DALIseconds. For example, turning all lighting fixtures 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 a smaller number of ballasts. Groups and Scenes solve that.

===Device groups===

Using the DALI Group previously definedassigned for theto ballasts in the room, if Short Address 1, 2, 3 and 4 are members of Group 1, e.g.:

* DALI Group address 1 go to 100%

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==

Devices store 16 programmable output levels as "scenes". AIndividual, singleGroup broadcastor commandALL causesdevices eachcan devicerespond to a global Scene recall command to change to its previously configured level, e.g. dim lights over the audience and bright lights over the stage. (A programmed outputbrightness level of 255 causes a device not to not respond to a given scene - hence be excluded from scene recall commands.)

==System Fail brightness==

A 17th "system failure" scenelevel iscan 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.

==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}}

==Scenes==

Devices store 16 programmable output levels as "scenes". A single broadcast command causes each device to change to its configured level, e.g. dim lights over the audience and bright lights over the stage. (A programmed output level of 255 causes a device not to respond to a given scene.)

A 17th "system failure" scene is triggered by a loss of power (sustained low level) on the DALI bus, to provide a safe fallback if control is lost.

==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.

WhenExcept 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 athat targetthe opcode is a (light) level byte follows(ARC), and "1" meaning that the opcode is a command follows.

SeveralMulti important specialpacket commands are used tofor savemore thecomplex datatasks byte- tolike onesetting ofRGB thecolors. 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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DiiA published several [https://www.digitalilluminationinterface.org/specifications/download.html new specifications] in 2018 and 2019, extending DALI-2 functionality with power and data, especially for intra-luminaire DALI systems. Applications include indoor and outdoor luminaires, and small DALI systems. The [https://www.digitalilluminationinterface.org/d4i/ D4i trademark] is used on certified products to indicate that these new features are included in the products.

==Colour control (DT8)==

IEC 62386-209 describes colour control gear. This describes several colour types - methods of controlling colour. The most popular of these is Tc (tunable white), and was added to DALI-2 certification in January 2020.<ref>{{cite web|url=https://www.digitalilluminationinterface.org/news/201/tunable-white-tc-colour-control-is-added-to-dali-2-certification|title=DiiA News|year=2020|website=DiiA Website|publisher=DiiA|access-date=4 March 2020}}</ref>

==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==

IEC 62386-104<ref>{{Cite web|url=https://webstore.iec.ch/publication/33330|title = IEC 62386-104:2019 &#124; IEC Webstore}}</ref> describes several wireless and wired transport alternatives to the conventional wired DALI bus system.<ref>{{cite web|url=https://www.digitalilluminationinterface.org/news/128/iec-publishes-part-104-of-iec-62386-describes-alternative-transport-including-wireless|title=DiiA News|year=2019|website=DiiA Website|publisher=DiiA|access-date=20 March 2019}}</ref> DiiA is working with other industry associations to enable certification of DALI-2 products that operate over certain underlying wireless carriers.

It is also possible to combine DALI with wireless communication via application gateways that translate between DALI and the wireless protocol of choice. While such gateways are not standardized, DiiA is working with other industry associations to develop the necessary specifications and tests to achieve this. [https://www.digitalilluminationinterface.org/wireless/ DiiA: DALI and Wireless]