Lighting- control systems - Intelligent Buildings and Building Automation - page 217

Table 10.2 Basic characteristic data of DALI

Maximum number of nodes in a single network 64

Transmission speed 1200 bps

Data coding method Manchester

LOW signal 0 V (nominal)

HIGH signal 16 V (nominal)

Maximum control cable length 300 m

Signal supply current limit 250 mA

Nominal signal per node 2 mA

Number of levels 255 plus OFF (8 bit)

are arranged to provide the flexibility of re-coupling the controlling devices
and the load interfaces and changing the grouping of load interfaces without
changing the address number of ballasts in terms of controlling and pulling
for backward data. The ability to extract status data from the load inter-
faces is an important feature of DALI, which is done on the basis of pulling.
Important status data of a load, such as 'lamp failure', on/off status, light
level and load current, can be collected. This data is very useful for a BAS
in order to set up system monitoring and diagnosis to enhance the lighting
system performance.
Due to the popular use of DALI technology in recent years, many DALI
components are available from different manufacturers. Typical examples
of available components are: load interfaces (e.g. dimmers, electronic
transformers, electronic ballasts and blind and curtain controllers), control
panels (on/off control, dimming control, etc. for manual control), sensors
(e.g. light sensor, occupancy sensor, etc. for automatic control), and control
interfaces.
A control interface provides the flexibility and ability of a DALI system
to use non-DALI lighting components or integrate with other building auto-
mation systems. An example of DALI components in this category include
1-10 V analogue converter (allowing analogue controlled dimmable ballast
to be used in lighting systems using DALI control systems), DALI/LonWork
converter and DALI/EIB converter.

10.4 Systems based on common automation protocols
Chapter 5 introduced a numbers of standard protocols popularly used in
building automation systems. Some of these protocols, including other auto-
mation protocols, are used in the lighting control industry as protocols at
field network level. Some are used for integration of the lighting-control sys-
tems or integration of the lighting-control system with other BA systems.