Page 94 - Advanced Course

KNX ADVANCED COURSE

1.4.2 Open-loop Brightness Control
An open-loop brightness control system is more cost-effective but takes more time to
adjust in order to achieve the same effect as constant light control. It is also not possible
to compensate for the effect of lowered shutters as the system uses the external
brightness level as a control value.
This type of control is however particularly suitable in larger installations for achieving
measurable energy savings with little effort. In contrast to the closed-loop control system,
the operation of the open-loop system is absolute. The necessary control value (8 bit –
EIS 6) for the lamps (switch/dim actuators or dimmers) is derived, with the additional help
of the control characteristic, from the received lighting level of the brightness sensor. It is
then output as a bus telegram. The automatic control system can be interrupted at any
time e.g. by manual intervention of the user or by lowering the blinds. An event- or time-
driven return to automatic control is also possible. Some actuators enable the lighting to
be switched on or off when presence is detected, without having an effect on the control
system. This means that one characteristic curve can be used for several load groups in
various rooms.

Helligkeitssteuerbaustei - Konfiguration
Configuration of brightness control module

Brightness
control module
S1
Dim actuator
Detector
Brightness
sensor S2
Dim actuator

Window S10
Dim actuator

Figure 7: Principle structure of an open-loop brightness control system. A single sensor can
be used for a variety of different control characteristics

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