Introduction
DALI is not a product. It is on open protocol, an interface between DALI devices and controllers and is perhaps more properly known as IEC 62386, which is published by the International Electrical Commission. As such, it is an international Standard for digital control of lighting and other electrical devices. DALI is an acronym for the Digital Addressable Lighting Interface.

A key feature of DALI is that the open platform it provides allows seamless interoperability between numerous manufacturer's DALI-compliant products.

DALI devices
DALI devices must all have unique identifiers called a short address. The list of DALI devices includes dimmable fluorescent, compact fluorescent, and halogen lamps (via DALI transformers), LED dimmers and sequencers, DALI-switched HID luminaires, dimmers, fans, motors, et cetera.

Creative Lighting and DALI
Creative Lighting designs and manufactures DALI and DMX512 compliant products, and has extensive award-winning lighting and electronics design and engineering experience. As a result of all this experience, we can pass on a few useful tips to those contemplating a role in realising a DALI project, from tips for specifiers engineers and designers; tips for installers and tips for systems integrators.
Creative Lighting manufacture the purpose-built tool for DALI called the ADDICT which has reached its 5th anniversary since invention, with ongoing r&d since then. The current release is version 1.08 and it offers even faster commissioning and expanded features.

Tips for installers

BIT: Basic Installation Testing (last updated 27 May 2009)
by Lance Stewart, Creative Lighting (www.creativelighting.com.au)

The job for installers, typically electrical contractors, is to install, wire and prove out the DALI lines and DALI devices before handing over to a Systems Integrator (although some firms also do the integration). To 'do your BIT', these are the 5 simple steps to take:

The first stage of BIT requires no special tools (a multimeter and some hand tools only) and its as easy as 1,2,3!
BIT 1 - Lights work, BIT 2- DALI cables voltage-free, BIT 3- DALI cables OK,

The second stage of BIT requires a DALI tool, such as an ADDICT (eg the -eco model which is very quick and easy to use)
BIT 4-All lights receiving, BIT 5- All lights replying & addressed

BIT 1) Lamps On. With mains power to all DALI luminaires, ensure that all lamps are on and working. If not, remedy. If ok, go to BIT 2. 

BIT 2) Test the free ends of the DALI wiring and certify that they are free of power. At this stage the only devices connected to the DALI lines should be receivers eg luminaires and the like. Do not connect controllers and power supplies. If the DALI lines have power, remedy then repeat BIT 2. When the lines are voltage-free, go to BIT 3.

BIT 3) Turn on (or power) each DALI line's power supply and test the starting voltage (which is the power supply's output). The so-called 'high levels' (when nothing is communicating) for DALI are: nominally 16v dc, minimum 9.5v dc, maximum 22.5v dc. Check the rating on the power supply you are connecting to the line, then test that the output matches the rating. (For example, Tridonic PS at time of writing is 16.5v dc, Creative Lighting DIDIO PS is 21v dc). Then connect the power supply to the DALI line and go to the end of the line and test the voltage there. If the voltage at the end of each line is not within 2v dc of the starting voltage at the power supply, you have a drain on the DALI cabling which you should identify and remedy.  

BIT 4) Do not start Bit 4 until all fluorescent and compact fluorescent lamps are run in (run at full intensity for 100 hours before they are dimmed) or lamp life will degrade significantly.  
Do not connect DALI controllers yet. If the DALI power supplies cannot be on without the controllers also being on, disconnect the controllers. 
Using a suitable DALI tool (eg a Control Freak ADDICT), test the line with a continuous MIN/MAX command which will cause all connected lights on the line to repeatedly fade up and down in a continuous cycle. (Note that an externally powered ADDICT will supply power to the DALI line if no power supply is present.) Visually check that all lights on the line  fade up and down. At the same time, check that no additional lights fade up and down - remember you MUST NOT exceed 64 devices on the line: we recommend 63 or less (to allow a spare address during remapping), and preferably 50 or so (to allow for future changes). 
If ok, go to BIT 5, otherwise remedy and repeat BIT 4.

BIT 5) Using a suitable DALI tool (eg a Control Freak ADDICT), randomly address all devices on the line. Refer to your project documentation and compare the number of devices that are addressed by this method, compared with the expected number of devices (addresses) on the line being tested. If the numbers do not match, either use the DALI tool to find and remedy the addresses that are missing, or hand over to the project's Systems Integrator for them to identify the fault during commissioning (you will later need to replace any device identified as faulty). If it is ok, connect the controllers to the lines and then - congratulations! you have done your BIT!

Tips for specifiers

1. Lamps & lamp life, 2. DALI lines, 3. Drawings & Documentation, 4. Dali Products (Cabling, Brands, Power Supplies, Recommended) 5. Saving energy & avoiding complaints: occupancy sensors & daylight harvesting. 6. Operator training and maintenance including backing up device settings.

1. Lamps
a) All major types of fluorescent lamp sources can be dimmed BUT they must be first run in by powering on at 100% for a minimum of 100 hours / 4 days, or you are unlikely to achieve the rated lamp life. b) The life of fluorescent lamps is usually based upon switching duty cycles. You should mitigate the use of regular power cycling or short lamp life may result. Dimming up and down from as low as 1% to as much as 100% is generally considered to have no negative impact on life expectancy, once the lamps are run in. 

2. DALI line (previously also called 'loop' or 'bus')
The 64 device maximum per DALI line is just that: a maximum. A good rule of thumb is to allow no more than around 50 devices (addresses) per line, to allow flexibility to rework DALI lines down the track and add more DALI devices to lines, eg for future tenancy changes. Note that controllers and many peripherals (such as daylight and occupancy sensors and push button plates) are not assigned DALI addresses and therefore do not impact on the 64 device maximum. If the peripherals draw their power from the DALI, you need only ensure that the DALI power supply has sufficient current for them. Most brands of DALI ballasts for example draw <2mA each and are generally either 1 watt or 0.5watt in standby (lamp is off but power is on to the ballast).

The term 'loop' was previously used in the DALI Standard because DALI is bi-directional. A data 'loop' is NOT a closed wiring circuit - the data cabling must be terminated into the controller at only one end of the cabling run, hence the move to change the term 'loop' to 'line'.

3. Drawings & documentation
Mark the DALI addresses on your plans next to the symbol for each DALI device. The addresses should be in a logical order - eg all lights within a given room to have consecutive DALI addresses. There are a number of reasons for this and first among them is the need to quickly identify the location for a light that has reported a lamp failure. If you choose not to label the DALI lights with their addresses, you should at a minimum require the contractor to provide as-installed drawings that are labelled with the DALI addresses (and groups) for hand-over to the client.

Incorporate BIT and CDL Procedural Statements in your written Specifications (with an appropriate acknowledgement of the author please) to clarify the scope of works to be done by the electrical contractor and/or systems integrator.

4. Products & components
a) Cabling
The DALI standard requires a minimum conductor size of 1mm2 and a maximum voltage drop of 2v and cabling for the DALI should therefore be sized to suit. DALI is a two wire system, requiring mains-rated cabling, and has no polarity sensitivity. Many projects opt to use 5 core soft wiring and connectors (L, N & E plus DALI) which can save significantly on installation time and make tenancy changes in the future quicker and cheaper.

b) Mixing brands
The intent of the DALI standard is that compliant devices will work perfectly well with other DALI devices from any manufacturer. So you not only can mix brands, it is essential for all DALI devices to work together. If a manufacturer tells you that you must use their DALI peripherals (controllers, sensors, power supplies, etc) with their DALI devices (ballasts, motor controllers, etc), read the previous sentence again.

c) Selecting power supplies
Devices 'talk' by shorting the DALI line, to the DALI specified maximum current of 250mA. It is widely advised that you should NOT combine/parallel dc power supplies for DALI, so select a power supply that is as close as possible to the maximum shorting current of 250mA, particularly when using a lot of devices that draw their power from the line, and to allow for future changes and additions to the DALI. For example, at time of writing, the DIDIO PS is rated at 245mA, the Tridonic PS is rated at 200mA. Many other makes are rated below 200mA. A key feature of the DIDIO is that is not only a Power Supply for the line, it is also both a Serial Communications Interface and a Scene Controller, all in one DIN mount package. The DIDIO allows the specifier to have a simple pushbutton control panel at the switchboard, for emergency overrides and maintenance scenes. The pushbutton panel can comprise standard momentary bell press mechanisms and can be equipped with up to 12 buttons, each of which will initiate a different DALI Scene, for Scenes 1 to 12 respectively on each DALI line (each DIDIO is designed to control and power one DALI line only). 

d) Recommended DALI products
We have only worked with some of the many brands of DALI devices and controllers, but here are a couple we have no hesitation in recommending:
Ballasts - Tridonic and Osram QtiDALI
Controllers that interface with computers and computer peripherals - DALI Control/Monitor Software BM2600s and Expansion Units, software for control and monitoring including OPC solutions.
HID Luminaires with DALI control and feedback - Sylvania Lighting Australasia

5. Saving energy and avoiding complaints

There are three main approaches to automatic control that will save energy with DALI: Occupancy Sensing and Daylight Harvesting. 

a) Occupancy sensing
A successful occupancy sensing system will automatically fade lights down in a given area - and do so slowly enough for people to exit the area - and then turn the lighting off if there is still no one present in that area (or brighten if people re-enter). 

The main component to occupancy sensing is of course the motion sensors themselves. There are a plethora of sensors on the market, and in general those made by the security industry offer the biggest choice and many of the most reliable sensors at reasonable cost. Select sensors that are designed for the environment you intend to use them in. If you elect to use a standard security sensor, select ones that have a Normally Open (NO) setting and specify the NO setting for best results. The controller you select should be capable of running timers initiated by motion sensors, preferably with a warning period during which the lighting will hold at minimum light levels for a couple of minutes before turning the lights in that area off. 

b) Daylight harvesting
Daylight ingress can be a good thing, and it makes sense to reduce artificial lighting levels (and energy) when there is adequate daylight. However, implementing daylight harvesting should be approached with caution.

For example, consider a typical building in which the only daylight ingress is through the verticals eg windows/curtain wall glazing. If there is an unobstructed view of daylight illuminated surfaces (for example an exterior building wall), the internal spaces further into the building may appear gloomy, even if the actual lighting levels meet code. This occurs because normal human vision will automatically adjust to the brighter surface (in this case the external day lit surface) and, as a consequence, the brightness of the rest of the field will appear to be relatively lower - in this case, gloomy. 

Then there is the situation of the worker whose desk is closest to the source of daylight ingress. In a well planned control system, that worker's lighting will be dimmer than that of a colleague sitting at a desk deeper into the building (away from the daylight source). Whilst the actual light levels on both desks may be comparable, the perception of reduced lighting may give rise to complaint from the worker with the dimmer lighting because his overhead lighting is obviously operating at a dimmer level. 

Then there are the daylight sensors themselves, and these are often simple photo-dependant resistors or circuits, with an adjustable iris. They are generally oriented to face downwards so that they mainly 'read' reflected light, usually off a desk. This type of sensor has the advantage of being inexpensive and simple but they have no settings that relate to an empirical measurement such as illuminance and they typically drive the DALI device's ballast directly without using DALI commands. One pitfall with this type of device is that a bright surface moved beneath them (even a bald head) can cause the sensor to 'see' more light and so reduce the illumination of the lighting to which it is connected. Covering highly reflective surfaces with dark materials may also cause the light levels to change.

A good control system will track the changes in the lights which have such sensors attached, and will use that information together with site information to automatically adjust appropriate lighting around it, and to a lesser degree the lights deeper into the building. In addition, a good control system will avoid 'hunting' which can occur with passing clouds for example. 

Regardless of the control system however, if the sensor is not a DALI device, the light it is attached to cannot be controlled by DALI successfully except to either turn it off with a DALI off command or send it on - it will effectively be operating independently. It nonetheless can be monitored by the selected control system.

6. Operator training and maintenance

It is good practice to specify the use of a purpose-built tool for the commissioning of the project such as the ADDICT-sys, and the handover of that tool at the end of the project as an essential part of the training of operators and maintenance staff. 

In addition, the ADDICT is capable of backing up the settings of all DALI devices on each DALI line, so that future replacement of the devices can simply reload the device settings to match the addresses of the new devices with those of the replaced devices. 

The settings in a standard DALI device include being added to or excluded from any of up to 16 Groups, being part of or excluded from up to 16 scenes at programmable intensity levels including mask (which is used for devices that should take no action in that scene), fade times, fade rates, system failure level (loss of DALI), power on level, Minimum levels and Maximum levels; and all these settings may vary from device to device. Specifying that all devices are backed up to suitably named computer files for later retrieval is a sensible precaution to the eventual need to replace DALI devices and avoid unnecessary reprogramming costs.

Tips for systems integrators

1. Before commencement, work up a Functionality Statement (FS) that covers the all aspects of the intended operation of the DALI system, and have the FS signed off by the client or client's Engineers before you start. See the attached PDF file for an example of a Functionality Statement. Remember to cover the basics like fade times for DALI devices, groups, the scenes and the manner in which the scenes are controlled (push buttons, touch panels etc).

2. Using a DALI tool such as the ADDICT-sys, commence Commissioning of DALI lines and devices ("CDL"), starting with remapping. 
CDL assumes the use of purpose-built tools such as the ADDICT-sys. In larger projects where saving on manpower costs is important or projects in which trailing cables would be an unacceptable hazard, the wireless option should be added to the ADDICT-sys.

CDL1 - All DALI devices logically addressed according to plan        CDL2 - All group assignments done.     CDL3 - All device settings done and backed up.
CDL-4 Controllers connected, programmed and tested.       CDL5 - Operator/maintenance staff training and handover.

CDL1 - All DALI devices logically addressed according to plan
There are a couple of very good reasons to logically address or 'remap' the DALI devices and to record the addresses on a plan to be retained on site. Firstly, DALI features lamp failure reporting by address and on larger projects it will save maintenance staff time if they no exactly where to go to replace failed lamps. The second reason is that the device settings can be captured and stored against the need in the future to replace DALI ballasts and the like at the end of their service life. This requires a unique identifier for each device to match the settings with, and in the case of DALI the logical unique identifier is the device's (short) address. The ADDICT-sys offers device settings capturing (all devices on the line at once or one by one) and programming. Finally, remapping the DALI devices to a logical pattern makes the process of spot checking the lines easier as you only need to have a point of reference in the space to have some idea where to look next when sequencing the lights one after the other. During the remapping, if the BIT was not perfectly done, you may find duplicated addresses, which an ADDICT-sys will report (as bad replies because more than one device is attempting to reply at the same time because of the duplicated addresses). Simply set the duplicated address to CLR (clear) and then random address NEW devices only before remapping. The ADDICT will also advise the addresses randomly selected for the 'new' devices. 

CDL2 - All groups assigned
Controlling DALI devices by Groups obviously reduces network traffic for the controllers, leading to greater reliability, and grouping will often reduce the time needed to programme the controllers as well. With a tool such as the ADDICT, groups can not only be assigned to devices, but groups can be added to groups to make new groups that combine both groups; and groups can be used to change device settings for all devices in a group at once. Equally, the ADDICT-sys can assign ALL devices with new settings.

CDL3 - Device settings complete and backed up
All devices should be backed up to suitably named computer files for later retrieval as a sensible precaution to the eventual need to replace DALI devices and avoid unnecessary reprogramming costs. This can be accomplished using an ADDICT-sys either one by one, or all devices on the line. The ADDICT-sys can be used in the future to programme new devices with the original settings by first assigning the new devices to the addresses of the devices they are replacing. You then need only load the file saved for that DALI line or device and program using the captured settings with an ADDICT-sys.

CDL4 - Connecting, programming and testing controllers
The controllers should now be connected, as well as their power supplies and the functions agreed with the client in the Functionality Statement programmed and tested. 

If the behaviour of some DALI devices is not what you expected, you can use the ADDICT-sys to sniff the DALI line and capture the timestamped data packets on the DALI line to establish with certainty the commands being issued by the controller and the replies that are being generated by the devices. These captured packets also have English descriptors, and can be sniffed to a pc or saved and transferred to a pc. Refer to the ADDICT user manual for details on how sniffing operates.

CDL5 - Operator/maintenance staff training and handover
Once all functionality is working as intended, you should provide the Operator training on how to use the controls in your system and provide a user manual. More in depth training should be given to maintenance staff, preferably to include all technical manuals and a copy of the BIT process and possibly of CDL.

....more tips are coming as time permits. In the meantime if you have any questions, just ask!

Creative Lighting are lighting and electronics designers and engineers with more than 16 lighting design awards since our inception in 1989. We also commission a select number of DALI projects so that we can have first hand field experience to feed into our r&d efforts. Creative Lighting have also been making DALI-compliant devices for a number of years now.