DALI Control System
DALI is an addressable communications protocol. DALI stands for Digital Addressable Lighting Interface and is part of IEC 60929 Annex E. DALI originally appeared in the market place in the mid nineties and has been used, up till 2009, in relation to dimming applications. The DALI standard has been updated and covers a section for emergency lighting.
Advantages Of DALI
DALI has many advantages over other control protocols as it has been accepted by all the major ballasts manufacturers, meaning that any DALI interface should work correctly with any control system. Other advantages include:
- Simple wiring of control lines (no group wiring, polarity free)
- Control of individual units (individual addressing) or groups (group addressing) is possible
- Simultaneous control of all units at any time through broadcast controls
- No interference of data communication due to simple data structure
- Device status, lamp fault, current level, assigned group, battery status etc...
- Automatic search of devices
There are however a few limitations of a DALI network:
- Maximum of 64 devices per network
- Maximum of 16 groups per network
- Maximum of 16 scenes per ballast, per group
- Maximum of 250mA current flowing on the DALI network cable
DALI does not use a centralised controller to store any values, for instance, a lighting level for a scene is not sent by the network, just a command to say go to scene is sent. All the information is stored in the DALI device. A standard DALI ballast stores the following information:
- Individual address
- Group assignment
- Light scene values
- Fading times
- System failure level
- Power on level
DALI Power requirements
A DALI network has a maximum current capacity of 250mA, this is stipulated in the IEC standards. Each DALI device sinks a different amount so the current of DALI network needs checking to ensure this is not exceeded.
- Each ballast takes approximately 2mA
- Each switch plate takes approximately 10mA
- A Programming point takes 20mA
- Each Multi sensors takes 15mA
How DALI communicates
The DALI network works on a multi master system, basically, the last button pressed will take control.
As there is no central processor then all the information about the DALI commands is held inside the individual units, for instance, a ballast stores its own address, scene level, grouping, fading times, power on level and system failure level. All these are freely programmable.
A button stores its address, grouping, button command etc.. Each button can have various functions, i.e. it can turn on full, turn on at last level, store a scene, go to a programmed scene and many more.
Once a button has been pressed, the button issues its command on to the DALI cable, for instance, if the button command is set to 'group 3, go to scene 4' then the ballasts that are set in group 3 and have a scene 4 programmed will go to this scene, all other ballasts will ignore the command from that button.
In the event that a ballast or switch does develop a fault then it will not affect the rest of the network.
The majority of systems will require some commissioning, this could only take a few minutes but may take a long time for a large advanced network system. Once commissioned, the system will work with or without a computer being connected.
Commissioning involves assigning the ballasts in to groups, setting levels for the scene, assigning button commands, fade times etc..
If using a router system this can incorporate conditional events such as between the hours of midnight and 7.00 am, turn all fittings in groups 7 & 8 to off, or 'group one commands to be re-directed to group 2 if recalled between the hours of 7.00am and 5.00pm.
There are a whole host of different commands that can be accessed for buttons and the list is very long and far too long to be covered in this document.
Various switch plates and controllers are available.
|DDC100||Rotary with Push Switch|
|DDC121||2 Button Switch, 1 & 0|
|DDC122||2 Button Switch, up & down|
|DDC124||5 Button Switch|
|DDC125||7 Button Switch|
|DDC126||8 Button Switch|
|DDC170||Infra Red Receiver|
|DDC303||Infra Red Remote Control|
All switch plates have an infra red receiver unit built in (apart from DDC150) so the remote control will work with any of the above.
The switch plates can be mounted either in a single mounting frame or threes in a double mounting frame. The mounting frames have similar codes, DDC200S for the single frame and DDC200D for the double mounting frame.
|DDC311||Passive Infra-red Occupancy Detector|
|DDC313||Recessed Microwave Occupancy Detector|
|DDC314||Tilting Microwave Occupancy Detector|
|DDC401||Ceiling Mounted Power Supply|
|DDC402||DIN Rail Mounted Power Supply|
|DDC440||8 Channel Input Unit|
|DDC444||4 Channel Input Unit|
|DDC452||1000W Universal Dimmer|
|DDC455||500W Thyristor Dimmer|
|DDC491||1 Channel Relay Unit (2A)|
|DDC494||4 Channel Relay Unit (4 x 5A)|
|DDC498||8 Channel Relay Unit (8 x 10A)|
|DDC502||Programming Kit (Software + DDC180)|
|DDC503||RS232 AV Interface|
|DDC910||Basic DALI Router|
|DDC920||Advanced DALI Router|
|DDC942||Input Unit (8 Switched & 4 Analogue Inputs)|