Switch/shutter actuator 8/4gang 16A RMD
75318003
Switch/shutter actuator 16/8gang 16A
RMD
75310002
Technical
Documentation
© Berker GmbH & Co KG 2007
Version: 04.04.2007
Part 5
(Subject to prior change)
75310002.doc
Seite: 35 / 174
Centralized feedback for outputs in switching mode
After central commands or after bus voltage return, a bus line is generally heavily loaded by data traffic as
many bus devices are transmitting the state of their communication objects by means of feedback
telegrams. This effect is particularly remarkable when visualizations are used. To keep the telegram load
low during a 'bus initialization', the centralized feedback function of the actuator can be employed.
The centralized feedback function groups the switching states of all outputs in switching mode together in
only one telegram. The 32-bit wide communication object "Centralized feedback" contains the feedback
information of the individual outputs in a bit-oriented format and is organized as shown Fig. 9.
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Fig. 9: structure of the centralized feedback object
The object permits representing up to 16 outputs and thus up to 16 different switching states in a logical
format, with each output having one bit representing the switching state ("S" bit) and another one defining
the masking ("M" bit). The "S" bits correspond to the logical non-inverted switching states of the outputs and
are either "1" (on) or "0" (off). The "M" bits are "1", if there is such an output on the actuator. Likewise, the
"M" bits are "0", if there is no corresponding output on the actuator. In the latter case, the pertaining "S" bits
are permanently "0" because there is no switching state.
This results in the following object value formats if, for instance, all outputs are set to switching operation …
Object value format for switching/shutter actuator 4/8gang: "00 FF 00 xx", xx = switching states,
Object value format for switching/shutter actuator 8/16gang: "FF FF xx xx", xx xx = switching states.
The datapoint type of the centralized feedback is KNX-standardized (DPT 27.001). It could be used in
suitable visualization applications, for instance in public buildings like schools or hospitals, where the
switching states of all actuators are displayed centrally and not separately at the local control units. In such
applications, the centralized feedback can replace the 1-bit single feedback and thus reduce the bus load
significantly.