
Functional description
© 2006 ABB STOTZ-KONTAKT GmbH
46
ABB i-bus
®
EIB / KNX
3.5
Communication objects
In the following section, the communication objects are described which are
available for channel A or B (broadcast or central commands) or the
individual DALI devices (individual commands). Some communication
objects are dynamic and are only visible if the corresponding parameters are
activated in the application software. In the following description channel X
represents DALI outputs A or B. In this case the same communication
objects are available for both channels A and B.
For the DALI devices which are connected to channel A, the communication
objects “Switch/Status”, “Relative Dimming” and “Brightness value/Status”
are available to directly control each device.
Due to the relatively slow transmission speed of the DALIs
(1200 baud, EIB / KNX 9600 baud), it can lead to delays in the
execution of the individual DALI commands when an EIB / KNX
group is accessed. This can lead to the DALI lamps being
switched on unevenly.
It may also be the case that some group devices do not
implement the last dimming step as they have already received
a stop command when dimming in an EIB / KNX group. The
difference is eliminated again during the next switching on/off. A
slower dimming speed means a smaller dimming step.
In critical cases the switching on can be implemented with the
help of a scene command or a broadcast command for the
entire channel. In both cases, simultaneous switching of all
scene devices or the connected DALI device on the channel
occurs.
A DALI device must be selected first via the object “Select Device” for the
functions “Read Position”, “Read Brightn.”, “Lamp Failure”, “Ballast fault”,
“Burn in Lamp” and “Slave mode”. The next telegrams which are sent control
or monitor the individually selected devices.
The same channels are available for channel B, however for the functions
on/off, switching, dimming and brightness, the device must be selected via
an addressing object for channel B “Select Device” beforehand. This means
that the function of channel B can only be used with the corresponding logic.
The logic must first of all select the device before the function can be
implemented.