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Electronic Theatre Controls Inc

DALI and Response DALI Primer

A TL;DR summary of DALI

DALI is designed for office lighting

It's intended for situations where the lights are turned on before people arrive, adjusted a little (eg dim to a low level before a presentation), then turned off after people leave.

DALI is not suitable for any situation where you want to fade nicely all the way to or from zero/off, at a rate of your choosing.

It has (roughly) 7-bit dimming resolution, and a different (logarithmic) dimming curve than you may be used to.
Due to its history, very few DALI fixtures are physically capable of fading to zero, most choosing to match a fluorescent response and snap 'on/off' somewhere around 5-20%.

DALI is designed to be easy to install

The data pair is polarity-free, and it supports the same topologies and cable types that are commonly used to power office light fittings - daisy chain, home-run, spurs.
The data pair doesn't require a terminator - the end simply finishes in a fixture, or even simply capped off (in the same way as an unused mains voltage spur).
The data pair can be run in the same insulation jacket as the mains voltage power.

You can simply pull a five-wire cable (L,N,E, DA,DA) and connect that to all the fittings.
It doesn’t matter if you swap DA and DA, as long as you don't short the two together (eg in a ring).

DALI ballasts don't work out of the box

DALI Ballasts have to be "commissioned" before they are fully controllable. Until commissioned they will simply come on to full, and only respond to Broadcast level commands (eg from the DRd DALI Option Card)

Commissioning normally requires specialist tools, generally a DALI USB interface, laptop and DALI configuration software.

ETC Mosaic and Response DALI products can commission DALI systems:

- A Mosaic processor with a RIO-D and the Mosaic Designer PC/Mac configuration software.

- Response DALI automatically commissions the ballasts and sets up a 1:1 DMX patch.
An RDM controller (eg Concert) is used to change the configuration if the default settings are not suitable.

DALI is very slow

DALI is very, very slow compared to the other control protocols we're used to.

- RDM is about 10-100 times faster than DALI for configuration and reporting.
- DMX is more than 500 times faster than DALI for level setting.
- ACN and sACN are at least 100-1000 times faster than both RDM and DMX combined. (10/100Mbit)

A DALI Loop can only do somewhere between 10 and 40 "actions per second".
An "action" might be a single level change, a ballast setting change, or a ballast status check.
This means that any change can often take several seconds to be applied to the ballasts.

Configuration changes are at the slow end, levels changes are fastest.

This means that level changes can often result in a "popcorn" or "Hollywood warehouse" uneven fade effect, where luminaires 'snap on' at different moments and different levels appear to sweep across the luminaires.

This is the most common problem encountered in DALI installations, and is the source of many myths and legends about what you should do.

DALI has three key features intended to work around these limitations:
a) DALI Ballast Fade Times.
Fade times are built into the ballast, and handled there. This "smears" out snap changes, reducing the effect of uneven fades.
Note: The fade time applies to all level changes.

b) DALI Ballast Scenes.
This allows a single action to set multiple ballasts to a range of (potentially different) levels.
However:
- There are only 16 Scenes (for all 64 ballasts) and they must be pre-recorded into the ballast itself. This makes it difficult (and exceedingly slow) to change them.
- They all use the single fade time set by (a).
So if you want anything else - faster or slower fade, any different levels - you're back to the Hollywood warehouse.

c) DALI "Group" and "Broadcast" level commands.
Instead of sending a level change individually to each ballast (1.6 sec to send a single level to 64 ballasts), a single action sets the desired level of multiple ballasts at once.
A broadcast, group or individual level can be sent 40 times per second, so simultaneously fading two or three Groups gives each Group 13-20 levels-per-second.
- A little slower than DMX at ETC's "Slow" rate.

These three features can mitigate the uneven fades to some extent.

Response DALI automatically optimizes DMX level control from moment to moment.

Consequently:
DALI systems are not generally suitable for theatrical or cinema production-quality lighting, such as houselights.

DALI systems are very good for foyer, worklight, office, dressing room, rehearsal room, small conference room, corridors and similar lighting applications.

If you take away nothing else, remember this:
DALI is not intended for houselights.

Using DALI for houselights is like buying a standard-definition TV. Yes, of course it "works", but the picture is fuzzy and small.

If a site is considering using DALI (of any kind) for houselight control, the end user needs to see a demo of several of the proposed fixtures (in the dark!) so they can see and accept the limitations DALI will impose.
- Never just one fixture, as one of the most common annoyances is popcorning/uneven fades.

Try them out with a set of fades the user is likely to want, controlled with button push and/or fader as appropriate.
- All ETC (and most 3rd party) DMX/sACN lighting consoles can simulate Paradigm/Echo to this extent using submasters, GO and flash buttons, so a theatre can easily use their existing console for the demo.

If this isn't done, then the user is certain to be disappointed by their DALI installation.

Production-grade (ie DMX controlled!) LED houselight fixtures are not expensive, in some cases they might even be cheaper - ArcSystem is particularly good.

Response DALI

Response DALI has several unique features that give you far more responsive and flexible control than any other DMX to DALI interface currently on the market.

It commissions your ballasts and offers immediate live DMX control of all connected ballasts within seconds, with no configuration required
- Other than DMX addresses if 1 thru 64 isn't desired.

- Automatic commissioning (including automatic replacement of a failed ballast)
- Automatic DALI acceleration
- Ballast status reports via RDM

Response DALI Gateway DMX Operation:

Response DALI automatically uses the most efficient combination of broadcast, group and individual level commands as DMX levels are changed.

This reduces - and in most cases eliminates - the Hollywood Warehouse Effect (uneven fades).

Straight out of the box, all fades are smooth and responsive both when all lights are fading together, and when a small number of lights are fading individually.
- eg from fader or LCD stations.

Of course some installs often want many (but not all) lights to fade at the same time.
In this case, out of the box there may be some visible "warehousing" if more than 3-5 or so (but not all) lights are faded simultaneously.

To reduce this, the commissioning engineer can configure which Groups of ballasts will usually be at the same level.
- It does not matter what that future level might be, so these Groups are usually clear in early planning.

For example, a conference room might use three DALI Groups:
1) Overhead luminaires near the presentation screen.
- These will often be dimmed for presentations, then raised again after.

2) Overhead luminaires away from the presentation screen.
- These will often be kept bright during presentations.

3) Wall sconces/accent lighting.
- These will tend to be turned on when people enter and turned off at the end of the meeting.

As the same DALI loop might be controlling multiple conference rooms, each room will have its own set of DALI Groups.

Unlike with competing products, setting up Groups has no effect on flexibility.
The end user can still adjust lights individually in any way they desire.

Hint: Groups are only useful when multiple ballasts fade together.
Groups have little to no benefit if they only contain one or two lights - a single "presenter's spotlight" doesn't need to be in a group, it will fade just as well alone.

Hint: Each Ballast may be part of multiple different Groups.

Hint: In some cases it can give a nicer 'feel' to play back Paradigm Presets as zero-time (snap), and use the ballast fade time.
This is less useful if there is any manual control such as LCD or station faders, or lighting console control.

Note: The "Broadcast" personality mode is only intended for use with Lutron ballasts.
Lutron ballasts are not fully compliant with the DALI standard, as they do not support the Group and Individual DALI Level commands.
- Lutron may of course decide to correct this limitation in the future.

The default "Individual" personality mode should be used in all other cases.
This gives you both the best possible responsiveness and complete flexibility for the end user to customize the lighting as they desire.

The "DALI Scenes" workaround is not useful with Response DALI

Scenes are a common workaround with some DMX-DALI convertors, because they don't have Response DALI's automatic acceleration.

They're not included in Response DALI's DMX control because they make the normal use case of button and fader control very confusing.
- DALI Scenes can only be recorded by an engineer using a commissioning tool.
- If the ballast is at the level from Scene 1, the only thing the DMX controller (eg Paradigm) knows it that it's in Scene 1, so it can't display whether it's On or Off.
- As the DMX controller doesn't know the level, it can't predictably Take Control to turn it off, raise it, lower it, FlickWarn it etc.
(While a native DALI controller like M-RIOD can find out the current level, it takes 1 to 2 seconds, assuming nothing else is happening.)

The limit of 16 fixed DALI Scenes with one fade time is extremely limiting compared to our controllers.
- Paradigm supports hundreds of pre-recorded Presets which can be updated by the end user at will, and can be faded at any rate - including changing that rate during a fade.
- DMX lighting consoles often support many thousands of pre-recorded cues/presets.
- Paradigm and our lighting consoles offer instant live control of any set of channels - group or individual - and display their current level.

Response DALI Ballast Configuration via RDM:

Response DALI automatically backs up, commissions and configures all detected DALI ballasts at boot.
1) It discovers all pre-commissioned ballasts and backs up (or restores) their settings.
2) It automatically commissions all un-commissioned (brand new) ballasts.
3) If auto-replace is enabled and a single ballast has been replaced by a brand new one, it automatically configures that new ballast with the settings from the original.

Response DALI stores a complete backup copy of the DALI configuration and levels of all the DALI ballasts it knows about, as well as additional DMX/Response-specific information including the DMX address and ballast name.

When Concert (or any RDM controller) asks for the current value of a setting or status, Response DALI instantly replies with this information.

When you use RDM to change a setting, Response DALI immediately stores it locally and queues it up for transmission to the physical DALI ballast, if and when bandwidth becomes available and the ballast is online.

It replies to the RDM controller with an "ACK TIMER", to indicate that while Response DALI has received the new setting, it's going to take a while before the DALI ballast itself receives it. 
Most RDM controllers (inc. ETC ones) will then not send any further settings changes to Response DALI until that time expires, so be prepared to wait a while when sending lots of changes.
RDM controllers may not always indicate this situation.

Advanced: Pre-configuring DALI Ballasts using 3rd Party Tools

If you wish to commission ballasts using a 3rd party DALI tool, this should be done before the ballast is first connected to Response DALI.
Otherwise, Response DALI's backup copy of the ballast configuration will be out of date.

If you wish to use a 3rd party configuration tool to change ballast settings after Response DALI has already commissioned them or backed up their settings:
0) Note down DMX addresses and (optionally) ballast names.
1) Disconnect Response DALI from the DALI line.
2) Re-configure the ballast(s) using the 3rd party tool.
3) Delete the ballasts you have edited using DELETE_SUBDEVICE, or use "Factory Reset" to clear them all.
Caution: This will permanently delete the ballast name and DMX address, as these are not stored in the ballast.
4) With Response DALI power off, connect Response DALI back to the DALI line.
5) Power On Response DALI. It will then discover and back up the ballast configuration.
6) Set DMX addresses and (optionally) ballast names.

 

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