In this, An Introduction to DALI 2017, we will cover everything you always wanted to know about DALI (Digital Addressable Lighting Interface). Importantly this will cover what is known ‘till now about the DALI protocol and DALI2.
“DALI network consists of a controller and one or more lighting devices (e.g., electrical ballasts and dimmers) that have DALI interfaces. The controller can monitor and control each light by means of a bi-directional data exchange. The DALI protocol permits devices to be individually addressed and it also incorporates Group and Scene broadcast messages to simultaneously address multiple devices (e.g., "Group 1 goto 100%" or "Recall Scene 1")."
DALI (Digital Addressable Lighting Interface) is a transport mechanism and data protocol. DALI was developed jointly and the specification written by a number of leading manufacturers of lighting equipment. The standard protocol of DALI makes lighting control systems easier and simpler to specify and operate, while also promoting competition to reduce installed cost.
Equipment from one manufacturer can be connected to equipment from another manufacturer and due to the common platform, can communicate with each other.
DALI was based on the DSI protocol, which is today still used in HF fluorescent ballasts. One of the key advantages DALI has on earlier lighting controls systems is the ability for each DALI device to be separately addressed.
1-10V and DSI ballasts and drivers cannot be separately addressed limiting their control to a single group. Therefore DALI needs far less complicated and less expensive wiring setup compared to 1-10v and DSI systems.
DALI allows for up to 64 devices on a single DALI line. DALI Lines are also known as:
DALI devices include LED Drivers, LED Emergency Drivers, fluorescent HF ballasts, DALI Relay Device, DALI sensors, DALI power supplies.
Projects which require more than 64 DALI devices are delivered by installing multiple separate DALI Lines with up to 64 DALI devices on each DALI Line. These separate DALI lines can then be simply linked together into a larger DALI Lighting Control System with smart DALI systems.
In 2015 smart DALI systems are connected to each other via secure - encrypted and authenticated - Ethernet backbones and require no gateways or translators to achieve cross DALI line control and building wide control.
Officially the DALI 2 specification has been released and includes part 103 (Control Devices). The DALI standard (IEC62386) - International Standard for Lighting Control - has been cleaned up and tightened up to allow for better interoperability of DALI devices from different manufacturers and backwards compatibility with the original standard. DALI is administered by DALI AG, with over 110 international members.
DALI 2 introduces Input Devices and sets the basis for future incorporation of Control Devices. DALI 2 includes, for the first time, standardisation of Control Devices and increases the scaling of DALI applications right up to building automation from a standards perspective.
There are a lot of DALI devices on the market today which are not DALI Compliant and are only DALI compatible.
Essentially this means the manufacturer has used parts of the DALI standard and embedded those parts into their product, have not had the product tested against the DALI standard though official testing methodologies and may not be a member of the DALI body.
This DALI compatibility does not always extend to full DALI operation and interoperability, depending on the how the manufacturer has implemented DALI. What this means is that those DALI compatible only products may not work correctly with other, DALI compliant devices, depending on what is being done. DALI Compatible devices are not permitted to carry the DALI logo.
To better secure facilities and future proof for maintenance, DALI Compliant devices are the best choice.
DALI compliant devices will have the official DALI logo on them. If in doubt it is possible to check the authenticity of that logo by searching for that manufacturer on the DALI AG website. All manufacturers who use the DALI logo on their products must be a member of the the DALI AG body and have those products listed on its website.
DALI Lighting Controls Systems will:
DALI Lighting Controls Systems will not:
As installed systems age maintenance personnel are typically asked to undertake replacement of failed drivers or ballasts.
Normally with 1-10V or DSI this is a straight forward task. This is not always the situation with DALI drivers and ballasts depending on which DALI system is being used. Even though DALI is a standard, that standard does not define exactly how each component should be manufactured, commissioned or setup, only that they have a common communication protocol and electronics makeup.
As each DALI device - HF ballast, LED Driver, DALI Relay device and so on - each have their own unique DALI Short address, the DALI device being replaced ideally will either have its address set prior to reinstallation or maintenance staff will have a simple DALI Short Addressing Software.
This process of DALI device replacement has previously caused a lot of facilities to spend significant money on what is now a simple process.
However some older DALI systems still require these replacements to be done in the old fashioned way with cumbersome software and processes due to old system hardware or maintenance agreements.
However because of the DALI standard, these new systems can easily undertake this re-addressing as part of maintaining a DALI lighting control system, without interfering with the older, pre installed DALI system.
|Maximum Cable Length||300mtrs|
|Maximum DC Supply||250mA|
|Maximum Number of DALI Short Addresses||64|
|Maximum Number of Groups||16|
|Maximum Number of Scenes||16|
|Data Baud Rate||1200 baud|
|Control Type||Control Cable||Control Signal||Polarity Dependant||0% while Energised||Individually Addressable|
|DALI||2 Wire Mains Rated||Manchester Encoded||NO||YES||YES|
|DSI||2 Wire||Manchester Encoded||NO||YES||NO|
|1-10V||2 Wire||1-10 Volt DC Analogue||YES||NO||NO|
The DALI standard states that each DALI device requires 2 wires connected. Some may also need a mains power supply connected.
Importantly these 2 wires are not polarity dependant, simplifying installation. In Australia because there is only functional isolation between the mains and the DALI devices, these wires must be treated the same as mains, due to mains potential. Therefore the 2 wires must be double insulated to adhere to Australian Standards and this may be different in separate countries.
DALI Lines need a maximum of 24V DC 250 mA power supply to operate. Systems will operate on less mA depending on the number of DALI devices connected but DALI power supplies cannot supply more if they are to being DALI compliant.
The voltage available on the double insulated 2 wires can be used to supply power to all connected DALI devices such as drivers, ballasts, DALI relay devices, sensors and more. The DALI Power Supplies are best to be installed separately in case of failure.
Whilst some DALI systems offer integrated DALI power supplies, if this power supplies fail the entire DALI Line controller needs replacing. This can often lead to significant delays and re-programming.
By having separate DALI power supplies for each DALI Line, if a power supply fails it can be easily replaced without affecting any other part of the DALI setup or installation and no re-programming of any kind is necessary.
Below is a table detailing the recommended DALI cable or conductor gauge required for DALI lines of different lengths.
|DALI Cable Run Length||Recommended Minimum DALI Cable Conductor Size|
|Less than 100 Meters||0.5mm²|
|100 to 150 Meters||0.75mm²|
|More than 150 Meters||1.5mm²|
|More than 300 Meters||Not recommended, avoid runs over 300 Meters|
All DALI devices consume power when operating and typically this power is provided via the DALI power supply and 2 core, double insulated cabling.
As DALI drivers and ballasts can dim their lamps to 0% light output, a simplification of cabling can be achieved as their is no need to isolate the power to a lighting circuit to have no light emitted. This ensures DALI lighting systems can save energy easily.
A typical DALI commissioning process will begin by identifying each of the DALI devices, assigning a short address, creating DALI groups and creating DALI scenes. This information is then recorded on project paperwork.
Alternatively this DALI short address, group and scene information is prepared prior to visiting site and is pushed into the DALI devices as part of the commissioning process.
As each DALI devices stores all of its own DALI Short address, DALI group and DALI scene information this provides for sophisticated control from simple control hardware. As DALI is a digital interface this can also be called a Digital Ceiling.
Previously this process was very slow and time consuming but with modern DALI Short Addressing Software it is now possible to commission DALI systems with mobile devices which makes DALI commissioning rapid in comparison to the old processes. This eliminates one of the major detractors of DALI systems - time to setup.
DALI devices have two addresses and in most instances only the short address is relevant when commissioning a DALI system.
The DALI Short address allows a maximum of 64 devices on a DALI line. Each DALI device will ideally have a unique address and this DALI Short Address is typically used for control of the DALI system.
All DALI devices can be a member of up to 16 different groups of control.
In this way a DALI command can be sent onto the DALI line from a DALI controller, control panel, sensor or other interface to call a DALI Group message. All DALI devices which are a member of that DALI group will respond accordingly.
It is also possible to operate a DALI line in DALI Broadcast mode.
In broadcast mode a single command is broadcasted to all DALI devices on the line. It does not matter if they have been assigned to any groups or if they have a DALI short address assigned. The DALI Broadcast command allows for full control of all DALI devices connected to a DALI line.
This is a fast way to execute a DALI system and provide DALI Line control of all connected DALI devices. It does however mean that it is not possible to individually control a DALI device with DALI Broadcast.
If however there is no need to control devices individually or receive feedback from individual devices such as ballast or driver failure, lamp failure, then DALI broadcast has its place.
The DALI protocol provides 255 levels (0-254) with the 256th level (level 255) denoted as “MASK” which typically means to do nothing.
It does not correlate to a lighting level but rather a brightness between off and 100%. These light levels are translated via a logarithmic curve to light output levels.
This logarithmic curve provides larger increments in brightness at high output levels and smaller increments at lower brightness or dimming levels. It is believed that this curve better replicates the sensitivity of the human eye’s ability to gauge changes in light. This does cause issues across different drivers and ballasts from different manufacturers with different lights sources.
However, as part of the DALI standard each DALI driver or ballast also has a linear dimming curve which can be accessed if the logarithmic curve does not suit the application. Not all DALI control systems are capable of activating the linear curve, so care should be taken when selecting which DALI Control system to use.
Part of the DALI standard covers DALI Emergency drivers and ballasts. In this way it is possible to have DALI compliant Emergency equipment which, due to DALI’s capabilities, can provide a complete Monitored Emergency system with different components from different manufacturers.
These DALI Emergency Monitored Systems allow facility managers and other stakeholders to automatically schedule and run tests on their emergency DALI lighting egress systems, receive reports on which devices have passed and failed and plan for maintenance as needed to ensure building safety and standards compliance.
DALI Emergency Systems and DALI Lighting control systems can co-exist on the same DALI line as the DALI Complaint drivers and ballasts have sufficient in built technology to identify themselves and their profiles to the DALI controllers.
Some DALI Control systems are also capable of providing both functionalities from a single control system.