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Explain the different Lighting Communication Terminologies
What are the features found on a touch screen?
What is a touch screen?
What other methods could you use for scene setting?
How would you use a user interface?
What products would you use to program lighting scenes?
What is scenesetting?
How do you dim fluorescents?
What the advantages of adaptive dimmers
What is a transistor dimmer?
What are the concerns with electronic transformers?
What is an inductive load?
What is the difference between triac and thyristor
How does a dimmer work?
the different Lighting Communication Terminologies
the lighting industry there are many names, codes and acronyms
that are used to describe the communication between lighting control
devices. Some are industry standards others are manufacturer specific.
Below is a means of removing the mystery and defining how different
market segments use different communication means.
Fluorescent ballast control
There are 3 means of controlling fluorescent ballasts. Two of
which are industry standards, the other from a single manufacturer.
·1 – 10V
This still remains the standard means of controlling the light
level of fluorescent ballasts. Ballasts with this control incorporate
a dimming circuit controlled by an analogue 1 – 10VDC control
voltage (EN60929 standard). Mains power to the ballast is switched
separately and externally to the ballast.
This is digital ballast control from Tridonic. The primary advantage
that DSI ballasts have over the 1 – 10V control is that they have
an internal electronic power switch. By using the digital control
pair, the power can be switched on/off as part of a control message.
This removes the requirement to separately switch the power supply
to the ballasts.
DALI is short for Digital Addressable Lighting Interface. The
major European ballast manufacturers have devised this standard
and it offers similar benefits to DSI.
These ballasts offer integral controls and scene setting functions.
However a DALI system requires addressing of each ballast or device
and each network is limited to a maximum of 64 DALI ballasts or
devices such as control panels and sensors.
Audio Visual Integration
The Recommended Standards (RS) below are purely the means of communication
not the message / protocol. DMX, for example, uses RS485 as the
bus with the DMX being the protocol. Many manufacturers use the
RS buses and have there own protocols written in either hex code
or ASCII characters.
RS232 offers simple point-to-point communication between two devices
at relatively slow data rates (up to 20K bits/second) and short
distances up to 15m.
RS422 (differential) was designed for greater distances and higher
Baud rates than RS232. Data rates of up to 100K bits / second
(Baud) with distances up to 1200m can be accommodated with RS422.
RS422 is also specified for multi-drop applications where one
driver is connected to, and transmits on, a "bus" of receivers.
RS485 is similar to RS422 in terms of data rates and distance
but allows multiple devices to talk to each other rather. RS485
has generally replaced RS422.
Entertainment lighting control
DMX512 is the internationally accepted standard of communication
for entertainment lighting products, such as control desks, dimmer
packs, moving lights and colour scrollers. As the standard DMX512
implies, there are 512 control channels available on a single
network and the protocol runs on a RS485 bus at 250K bits / second
(Baud) at 750m.
Advanced Control Network (ACN) is a new control protocol that
will run on a standard Ethernet bus. It is currently in the design
process in the United States.
Integrated bus and protocol systems
There are a number of integrated bus and protocol systems that
are used across the building industry. Below are the systems that
are also used by the lighting industry. All of them offer distributed
control; i.e. there is no central control system, each device
on the network is part of the intelligence collective. They are
all open standards, i.e. the protocol is easily available and
open to a manufacturer to produce compliant product.
CAN is an acronym for Controller Area Network. This is a bus system
developed by Robert Bosch GMBH, for use in the automotive industry.
Because it was developed to work in highly hostile environments,
it is intrinsically stable and reliable.
It is now used by a number of lighting control manufacturers due
to its reliability and cost effectiveness.
Echelon’s LonWorks platform is an open standard for control networks.
LonWorks can be made up of a variety of LonWorks compliant products
linked together on the same LonWorks network.
LonWorks is used in factory and building automation.
European Installation Bus (EIB) is widely in continental Europe
for building automation, both commercial and domestic. Insta is
a collective of German electrical accessory manufacturers who
make a variety of EIB control components.
are the features found on a touch screen?
graphical “tell back” control of each and every circuit within
Virtual fader control for manual operation of circuit levels.
Hidden page and function capability. This will provide (for example)
a hidden programming page for the lighting designer to program
An automatic screen fade down function which reduces the screen
brightness automatically to a non-intrusive level after a programmed
time out period.A programmable “return to welcome page” function.
The LCD touch screen communicates directly with the iCANnet™ network.
Messages are both transmitted and received, allowing remote monitoring
of control panels and sensors.
is a touch screen?
this method of control all manual, scene set, time clock and graphical
control can all be integrated into one simple control panel. The
LCD touch screen is a flexible device which provides an intuitive
"user friendly" method of interfacing to the lighting control
system. The LCD touch screen provides virtually a limitless flexibility
of system configuration and control.
This method of control is ideal for areas where complex and flexible
control is required. It is completely software based, and programs
can be tailored to suit the precise needs of the user. It also
offers many advantages over conventional control panels not least
of which are multiple control functions. For example in a hotel
suite, these units can be programmed to control the lighting,
the motorised curtains, the air conditioning, the TV, and any
other device that is fitted with the appropriate control interface.
The screens can be programmed in a highly graphical way to guide
the user through what they should do to achieve the desired result.
This is particularly useful where users have a variety of languages
or levels of skill.
other methods could you use for scene setting?
methods of accessing the preset scenes are from LCD touch screen
controllers, time clock, PE/PIR units, wireless remote hand held
controls, central PC controllers with remote access and Audio
Visual and Home control systems, as well as Building Management
Time Clocks and PE/PIR Photo Electric/Passive InfraRed units enable
the scene selection process to be automated. This method ensures
that the correct scenes are set at the appropriate time of day
and day of the week.
PE/PIR units allow scenes to be triggered or selected automatically,
depending on ranges of natural light intensities or by persons
entering a room or area in a building.
would you use a user interface?
user interface to the scene setting is usually by means of a push
button control panel, mounted at a logical position within a room.
In many applications there will be several controls operating
in parallel. Each button cap is back illuminated when active,
and will invariably have a legend with the name of the scene.
products would you use to program lighting scenes?
programming of the lighting scenes is done using either the control
panels themselves, a hand held programmer which is removed once
the programming is completed or a laptop computer with dedicated
programming software (iCANsoft™). The secure memory facility in
the iCAN™ source controllers provides a capacity for over 128
scenes, which is more than adequate for even the most demanding
There are very many different applications for the scene setting
the theatrical sense a scene takes place in a dramatic context,
hence the expression setting the scene (or in an architectural
sense, setting a mood). As the story unfolds, so the look and
feel and structure of the scenes within a play will change. The
lighting is a fundamental part of this mood setting. Indeed the
Set in a play may remain unchanged through a complete act, but
as part of the illusion process in theatre, the lighting directs
our attention to where the action is. Clever and creative use
of lighting in theatre enables very basic Sets to be dramatically
manipulated to spectacular effect by the director.
The same principles of lighting apply in an architectural application
do you dim fluorescents?
method of dimming of fluorescent lamps is dependant on the type
of dimmable ballast being used. This is dealt with in greater
detail in the technical information Section entitled ”Load Compatibility“.
Note however that there is a vast array of different fluorescent
lamps available. As a general rule, only those with 4 pins are
dimmable. Furthermore, they must be supplied with ballasts that
are electronically dimmable. Whilst there are still some mains
voltage dimmable ballasts available, in general terms these are
either themselves prohibitively expensive or do not comply with
CE directives on EMC, Safety or the Low Voltage Directive. Use
of the latter devices within the EU is illegal.
iLight™ has a range of HF Ballast controllers that are compatible
with all commercially available dimmable ballasts available in
As a rule these fall into three types:- The most common units
require the mains supply to be switched on or off, and the intensity
of the lamp is determined by a control voltage in the range 1->10
The second popular ballast is the digital ballast available from
Tridonic. These are referred to as DSI ballasts. The primary advantage
that these ballasts have over the 1->10-volt units is that
they have an internal electronic switch. By using the digital
control pair, the power can be switched on/off as part of a control
message. This removes the requirement to separately switch the
power supply to the ballasts. Finally, there are DALI ballasts.
These will become commercially available in early 2001. In theory
these ballasts offer integral controls and scene setting functions.
In practice the concept requires a random addressing of each ballast.
This would mean that commissioning or maintaining installed systems
would be difficult and expensive. Each network is also limited
to a maximum of 64 ballasts. It is understood that most ballast
manufacturers will be offering units with both 1->10 volt control
as well as DALI.
the advantages of adaptive dimmers
has developed an FET (field effect transistor) source controller
that solves all the load compatibility problems inherent in loads
controlled by both triac and transistor dimmers.
In the iLight™ Adaptive Dimmer, both the voltage and the current
are monitored, and this is linked into the CPU which controls
the dimmers operating parameters. This control is dynamic and
offers several major benefits over conventional dimmers.
These adaptive source controllers will work with resistive, capacitive
and inductive loads. They will also detect reactive loads. If
a reactive load is connected to the dimmer, it will immediately
switch to full on, thus avoiding any possible damage to the gear
associated with that circuit. Alternatively, the unit can be configured
to switch off, if that is the user preference.
When the adaptive source controller “sees” an inductive load,
it adopts a leading edge dimming mode. Furthermore the patented
iProtect™ circuitry within the source controller can determine
if the load is too great for it to cope with. In this case the
unit will immediately switch off. However, in the case where the
lamp inrush current is the reason for the overload* the dimmer
will attempt to turn on every half cycle. Each time it tries a
small amount of energy is transmitted to the lamps. This energy
has the effect of warming up the lamp filament. As the temperature
rises, so does the resistance of the lamp, thus reducing the current
passing through the filament. After several cycles, the filaments
will have heated up sufficiently to offer sufficient resistance
and so the monitoring circuitry within the source controller will
allow full control or illumination of the lamps.
Should the adaptive source controller identify a resistive or
capacitive load, then it will adopt a trailing edge dimming methodology.
This has the added benefit that the unit will be then totally
silent in operation - because trailing edge dimming techniques
result in there being no magneto-striction in the suppression
chokes (used for RFI (EMC) suppression).
The other major advantage of this technology over conventional
dimmers is that the speed of “turn on” can be precisely and dynamically
controlled. In entertainment lighting, there is a requirement
to be able to flash lights on very quickly. However, when theatrical
lamps are turned full on instantly, the filaments suffer thermal
shock. This shock reduces the life of the lamp. By optimising
the turn on time in a dynamic way, the fastest possible turn on
times may be achieved whilst minimising the thermal shock to the
lamps and thus dramatically extending lamp life.
is a transistor dimmer?
number of dimmer manufacturers produce transistor based dimmers
which operate in a different fashion to triac dimmers making it
compatible with electronic (capacitive) transformers even if they
are not designed for dimming applications.A transistor dimmer
switches the supply off and is commonly known as a trailing edge
dimmer. By switching the current off the possibility for voltage
peaks is eliminated.
are the concerns with electronic transformers?
wire wound transformers, which by their very nature are dimmable,
electronic transformers may induce problems and care must be taken
when selecting electronic transformers to ensure compatibility
with dimmers in a control system.
Almost all dimmers in the UK employ triac or thyristor pair circuitry
to control the mains voltage sinusoidal waveform which reduces
the energy flow and hence the light output in a lamp.A triac dimmer
switches the supply on and may be known as a leading edge dimmer.
When used with an electronic transformer that has a capacitive
nature, an amount of overshoot can occur resulting in higher than
normal peak-to-peak voltages.
A transformer that has been designed for use with triac dimmers
should not produce these peaks. A transformer that is not designed
for triac dimming may work but is likely to emit audible noise
when dimmed. This noise is usually a symptom of internal stress,
which in turn can cause failure of the transformer. This problem
will become worse with more fittings on a circuit.
is an inductive load?
above examples hold true for mains voltage tungsten loads but
low voltage fittings introduce a transformer into the circuit
that makes the load more complex. With a mains voltage incandescent
lamp, which has a resistive characteristic, the voltage and current
waveforms are almost identical. On the other hand, a wire wound
transformer is an inductive load and the current tends to lag
behind the voltage. Once triggered a triac or thyristor relies
on the current flowing through the device to keep it conducting.
Should the current fall below the device’s threshold level it
will turn off and stop conducting. However with an inductive load
the current ’lags‘ behind the voltage so it is possible that the
current through the triac will not reach the triacs threshold
level before the trigger pulse ends. This results in unacceptable
dimming performance. To avoid this, dimmers designed for use with
wire wound transformer fed loads use what is known as a hard firing
technique. This ensures that the trigger pulse is maintained for
a long enough period of time to ensure that the current reaches
the device’s threshold level.
is the difference between triac and thyristor dimmers?
and thyristors are similar components; a triac is essentially
two thyristors combined in one package. Thyristors tend to be
more expensive but more robust. Triacs have the advantage that
they are less likely to “half wave” on failure and so the opportunity
for headache induced (50Hz) flickering and subsequent damage to
transformers is greatly reduced. Furthermore, when triacs are
over-rated, they offer a technically more elegant solution than
does a dimmer work?
are several types of dimmers generally available. Those employing
triac or thyristor devices operate in a very similar fashion. These
are used for resistive, and inductive loads, such as incandescent,
cold cathode and low voltage (inductive) lamp sources.Both act as
high-speed switches and in a dimmer are used to control the amount
of electrical energy passing to a lamp. They do this by ‘chopping’
the sinusoidal mains voltage waveform. A trigger or firing pulse
dictates at what point the device starts to conduct. The later the
device is fired the later it starts to conduct and hence less power
is transmitted to the lamp.