- Function blocks switchable, e.g. for day/night operation
- Brightness sensor function with 3 limiting values
- Alarm when unplugging from the bus coupler
- Temperature measurement
Motion detection function
The detection of movements is done through the "passive infrared" principle ("PIR"). The device
generally reacts to heat radiation changes within its detection area. This is achieved with the
help of the so-called PIR sensors, which are highly sensitive in the infrared range. The
geometry of the detection field is ensured by a lens system that lets infrared light pass through
and concentrates incident radiation on the sensors. So-called "detection radiation" are formed
through the lens system and cause a clear signal jump to be detected when they enter.
Note: The term "detection radiation" refers to the imaginary line that begins in the sensor, goes
through the lens system and continues in a straight line outside of the device. The device itself
does not emit any radiation.
Figure 3: Thermal image of a person and their reflection on the ground
The detection of heat sources through a motion detector is influenced by the following criteria:
- Geometry of the detection field:
A motion detector that faces downwards at an angle is different from one that looks straight
ahead into infinity (Figure 4).
- Distance between heat source and motion detector: the further away the heat source is
from the sensor, the weaker the evaluable signal on the sensor (Figure 4).
- Size of the heat source, e. g. adult or child (Figure 5)
- Temperature of the heat source: surfaces at 37 °C radiate more intensely than at 10 °C
(Figure 5).
- Contrast between the heat source and the environment: if the heat source radiates just as
intensely as the environment. detection will be significantly more difficult (Figure 5).
- Speed of movement: a faster moving object produces clearer signals in the sensor.
- Direction of movement: if detection radiation passes tangentially, this typically results in an
abrupt sensor signal which can be evaluated well. However, if a heat source moves radial
to the sensor, the sensor signal changes happen more slowly. This makes differentiation
from the background noise significantly more difficult.
- Concentration of the detection field: the number of sectors and switch segments of the
detection field determines the the concentration of the scan and therefore the response
behaviour.
- Sensor sensitivity: the sensor sensitivity can be adjusted according to application and
environment. Low heat contrasts outdoors may require a high sensitivity that is far to high
for indoor use. The sensitivity should be decreased in this case.
- Environmental medium: high humidity or rain can negatively influence the permeability for
infrared radiation.
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KNX
Motion detector Comfort 1.10 m, Motion detector Standard 1.10 m
