DMX VS DALI
DMX is a theatrical and entertainment lighting, Mostly used as Stage lighting. It is a streaming
protocol, with each stream – called a ‘universe’ – carrying up to 512
‘channels’ of data. All fixtures receive data for all channels, which is sent
by the controller at a specific refresh rate (such as 33 times per second).
The protocol does not assign any specific meaning to the
channels, so the controller must be aware of what is expected by the fixtures.
Each fixture listens for a specific number of channels (such as three for an
RGB fixture), starting at a particular channel number (the fixture’s
‘address’). The number of fixtures supported per universe therefore depends on
the channel footprint of the fixtures in use.
DMX assumes a centralized control system, which receives
input from any sensors or control interfaces and sends data to all fixtures.
DMX is transmitted over shielded twisted pair cable, with all fixtures
connected in series. DMX over Ethernet protocols are also available, for
transmission of many universes over a single cable.
DALI is a command-based protocol that specifies a set of
messages that controllers can send to fixtures. Instructions include scene
recall, setting a fade time and setting a level. DALI has free typology, it can
be used with any standard mains cable, it is polarity independent and can be
installed in a mains channel. DALI can support up to 64 ballasts per bus, 16
groups and 16 scenes per ballast, and 16 fade times that range between 0-95s.
One or more control elements (such as sensors or user interfaces) can be
present on the DALI bus to send DALI instructions. As such, DALI does not
require a centralized control system.
DMX cannot be connected directly to DALI or vice
versa. You have to use an Interface to connected DALI to DMX or vice versa. However, there are ways to use both protocols in the same installation. See some interface converter here.
Each protocol has its strengths and weaknesses, and the
exact same results cannot be achieved with both.
The following points may help
you in your decision.
Synchronised changes.
The streaming nature of DMX means
level changes are always synchronised. With DALI, changes will only be
synchronised if they result from the same instruction, for example the recall
of previously programmed scenes. However, because of the 16 scene limitation in
DALI, many control systems rely on sending individual set-level commands, which
will not be synchronised and can create a staggered ‘popcorn’ effect.
Dynamic effects.
DMX allows the colour and intensity of a luminaire to be changed every frame,
for example 33 times per second. This means that if your controller can create
dynamic effects, such as a wave, fades or subtle sparkles, they will be
displayed exactly as intended. The command-based nature of DALI can be very
limiting for dynamic effects. You might need to settle for low refresh rates,
staggered changes, or accept less control freedom, such as broadcasting to all
fixtures.
Fading control.
Fades in DALI are defined within the fixtures using steps, up to a maximum of
90 seconds. Not all DALI fixtures succeed in breaking up the required fade time
into a smooth transition. In DMX, fades are determined by the controller, with
advanced DMX control systems allowing fades ranging from zero seconds to 24
hours, and supporting 16-bit control for smoother fades (65,535 intensity
steps, rather than 255)
Number of scenes.
DALI fixtures support a maximum of 16
scenes. An advanced DALI system can effectively increase this number by
remembering extra scenes and sending those to fixtures individually when
required, but this results in unsynchronised changes. DMX scenes are stored in
the controller, with advanced systems supporting hundreds of scenes.
Emergency lighting.
The DALI protocol, unlike DMX,
includes specific emergency lighting functions, including testing and ‘level on
signal loss’ features.
Daylight harvesting.
Several DALI manufacturers have created systems to fulfill this
requirement using sensors connected directly to the DALI bus. Similar results
can be achieved with DMX using a controller capable of receiving input from a
sensor via a separate cable and processing of this PID loop.
Luminaire feedback.
The DALI protocol is bidirectional and includes messages like a lamp or ballast
error. Some DMX products support RDM (remote device management) commands for
reporting status back to the controller on the DMX cable. In both cases, it is
important to verify that both the fixtures and control system support the
desired feedback messages.
System integration, user interfaces and wall
stations.
DALI offers the ability to connect
control devices to the DALI bus and control fixtures directly. This is useful
where the desired control logic is relatively simple. DMX/RDM does not
typically support additional control devices on the DMX bus, but many
controllers can receive input over a separate connection. Control systems are
available for both protocols that can offer sophisticated control logic and
system integration via a centralised controller.
Ease of installation.
DALI is very convenient for installers because all devices and
control elements can sit on the same bus, with free typology. DALI is also
mains tolerant, and can be installed in the same conduits as the main cabling.
A DMX installation does not need to be difficult, but it does require a bit
more knowledge, care, and planning, especially if it includes sensors and user
interfaces via separate cabling.
There are many aspects where the quality, flexibility and
power of the control system are more important than the choice between DMX and
DALI. Both protocols can support installations up to many thousands of
fixtures. Tuneable white, RGB and other colour fixtures can be supported by
both protocols, providing both controller and fixtures support the same modes.
Similarly, many control systems can support numerous independent zones of
control.
DALI is great due to its installer friendliness, and
certain features (daylight harvesting, emergency lighting, multiple sensors)
are easier to execute using DALI. When using dynamic effects, or if
synchronised playback or specific fade times are required, then DMX will be a
better choice for your project. Most importantly, select a control system that
matches the features you need. A good controller or control system might
natively support both DALI and DMX to utilise the advantages of both systems.
How DMX and DALI Luminaires can be combined together in one Single System??
There are many valid reasons why you
might end up with both DMX and DALI fixtures on a project. For example, the
fixture you need may only be available in one of the two protocols. So what are
your options, and what are the advantages and disadvantages of each approach?
Protocol
converters
The benefit of using a converter is
that after initial setup, you only need to maintain a single control system.
The drawback is that DALI and DMX are very different protocols and cannot
achieve the same system functionality or results.There is a wide selection of DMX to DALI and DALI to DMX
converters in the market, all operating with a slightly different approach.
Some considerations when selecting a
DMX to DALI converter:
- What is outputted on the DALI bus? Can you recall scenes, or only adjust intensities? Can you control individual fixtures, or does it broadcast only?
- Refresh rates. Because DALI has a slower protocol, it will take seconds to send individual information to 64 DALI luminaires. When translating only a single DMX value (such as broadcast this to all connected fixtures) the speed can reach up to half that of the DMX.
- Repeating messages. Many converters will continuously send DALI messages on the bus, even if the DMX values stay the same. If you have sensors, button stations or other items on the DALI bus, this might not work, as the bus is flooded with DALI messages.
- How are the ‘DALI ballasts’ mapped to DMX? If I use RGB DMX fixtures, does this require three virtual DALI ballasts? Can I use all 512 addresses on the DMX bus, or must I start at one?
- How does it handle DALI fade times on the DMX side?
- Can I recall dynamic effects?
Some considerations when selecting a
DALI to DMX converter:
Two
independent control systems
You could simply install two
separate systems, one for DMX and one for DALI. Of course, the drawback is that
the systems will need to be programmed and operated independently, so for
example you cannot ‘turn everything on/off’ or ‘change the setting’ with a
single push of a button.
Simple
linking
Many controllers offer the ability
to be triggered via contact closures. You could add some relay outputs to
system A, and use these as inputs to system B. This will involve a lot of
hardware and installation effort with limited results. Even though this happens
regularly, this should really be considered a substandard solution.
Controller
integration
Integrating two control systems
sounds complicated, but it does not need to be. If your controller can be
triggered by the other protocol, you can simply use that protocol to
communicate between the two systems, while retaining the advantages of each
protocol.
Suppose you have a DALI system where
a group will be replaced by DMX luminaires that need to show some dynamic
scenes. If your DMX controller can be triggered by DALI, you can use the DALI
messages to recall scenes and set intensities on your DMX fixtures.
Similarly, if you have a DALI
control system that can be triggered by DMX, you could use a specific DMX
channel for DALI scene recall, another DMX channel for intensity broadcast, and
so on. The control system needs to be intelligent enough to only send DALI
messages in case of relevant changes in DMX values. System integration can become very
advanced and use other communication methods than DMX or DALI, but if you just
want to combine DMX and DALI, it can be very simple. Many Manufacturer's offer a control
lighting solution that can be used to augment a DALI installation with DMX or
vice versa.
Here is the example:
A controller
system that supports both protocols
This is the most flexible and
powerful solution, and in many respects the simplest. There are control systems
that simply support both DMX and DALI, achieving the best of both worlds. These
need not be advanced building management systems, they can also be simple
standalone DIN-rail controllers. Of course, such a controller cannot
overcome the fundamental limitations of each protocol, such as making DALI
fixtures do the same dynamic effects as DMX, but will help you in programming
the environment to be set up to your dynamic and static lighting scenes as
required.
Besides DMX and DALI, there are
other lighting control protocols such as Bluetooth, Zigbee, and DMX over
Ethernet. Choosing a control system that can naively speak to other specific
protocols you have in your project is a good recipe to ensure you receive a
great programming experience.
Some controllers can output
DMX512, DALI, and DMX over Ethernet protocols like Art-Net, KiNet, and sACN.
Furthermore, Some, I/O modules allow you to directly control Xicato, Hue,
Philips Dynalite (and more to come) luminaires and load controllers, that can
be fully integrated with your DMX and DALI programming.
If you need more information, or need to ask question, please don't hesitate to contact us. our email: odie1427@gmail.com, we are gladly to help.
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