Digital Addressable Lighting Interface

Digital Addressable Lighting Interface ( DALI) is in building automation is a protocol for controlling lighting control gear such as switching power supplies ( " electronic transformer " ), electronic ballasts ( EVG) or electronic dimmers.

General

Each operating unit that has a DALI interface can be individually controlled via DALI short address and changed in intensity. Through a bi-directional data exchange, a DALI controller or a DALI gateway to query the status of lamps and control gear of a light or set the state. Each operating unit in a DALI strand Up to 16 groups can be assigned to allow a synchronous activation of the operating device. In addition, up to 16 atmospheres ( = predefined intensity control values ​​) stored per farm unit and recalled when needed. DALI can be considered " isolated system " to operate with a maximum of 64 operating units or as a subsystem via DALI gateways in modern building automation systems. In principle, DALI has established itself as a successor to the still dominant 1-10 V standard ( electronic ballasts with 1-10 V interface ), moreover, it is the successor of Digital Serial Interface (DSI ). The main differences are, firstly, that each DALI device can have different individual intensity control values ​​, whereas with 1- 10V or DSI all operating devices always have the same intensity setting value. Secondly, it is possible to 1 - 10V or DSI only a unidirectional flow of information (from the controller to the operating unit).

DALI uses a serial, asynchronous data protocol with a transfer rate of 1200 bit / s at a voltage level of 16 V. The control line is isolated and polarity free (polarity protected ). In the standard No definition for to use connectors, terminals and wiring has been made. The cables can be used in almost any topology, ie, star, line or tree structures to be relocated. However, an annular connection of the components should be avoided. The cable length between two system participants is limited (depending on the cable cross-section ) to a maximum of 300 meters. There are no termination resistors at the end of a line is necessary.

DALI provides the ability to take a certain " system error value " (so-called System Failure Level ), for the case that the open circuit voltage of 16V and a communication failure to the control gear is no longer possible.

Standardization

The IEC Subcommittee SC 34C edited the standard series IEC 62386 " Digital addressable lighting interface ".

Additionally, in the NEMA DALI is normalized:

Properties

The planning and commissioning of DALI systems requires good consideration. So you need to consider important boundary conditions, which are derived directly from the IEC 62386:

• There are a maximum of 64 actuators per DALI bus allowed.
• The maximum power consumption of a DALI circuit is 250 mA.
• The power consumption per DALI actuators ( a DALI load ) is at most 2 mA.
• The maximum voltage drop between transmitter and actuator must not exceed 2 V.

Further constraints arise indirectly from the standard:

• The cable length is (when using 1.5 mm ² conductors ) 300 m.
• When utilizing the maximum cable length, it is not advisable to install DALI in combination with the power line.
• Not all types of installation of the bus are allowed to ring form is to be avoided entirely.

The energy supply of the DALI components is usually via a separate power supply.

The isolation of the digital interface conforms to the requirements of basic insulation; the test is carried out according to the standard IEC 60 928 Thus SELV (Safety Extra lowVoltage ) is not guaranteed. An installation of connection cables for the digital interface with the power supply lines ( eg 230 V) can be carried out under the isolation conditions (2 x basic insulation). Often, therefore, the two are "free" lines of a 5x1, 5 mm ² NYM cable for the control lines (along with the other cores for phase, neutral and protective conductors ) are used.