Order No. 2104 ..
4.2.4.3 Sensor function
4.2.4.3.1 Temperature sensor
Basic principles
The temperature sensor of the device measures the actual temperature of the room cyclically.
The measured value can be transmitted instantly to the bus via a separate 2-byte object, and
thus be made available to KNX display components. The temperature sensor is also used for
the integrated room temperature controller for measuring the room temperature. The control
algorithm calculates the adjusted command value from the difference between actual and
setpoint temperatures.
Further information concerning the room temperature measurement of the controller can be
looked up in the corresponding chapter of this product documentation (see page 99).
The temperature sensor is integrated in the room temperature controller. Alternatively (e.g. if the
room temperature controller has been installed in an unfavourable location or operates in
difficult conditions, for example, in a moist atmosphere) or in addition (e.g. in large rooms or
halls), a second temperature sensor linked via bus telegrams can be used to determine the
actual value. This second sensor can either be a room temperature controller coupled via the
KNX or a controller extension with temperature detection.
Installation location
When choosing the installation location of the controller or the external sensor, the following
points should be considered...
-
The temperature sensor should not be used in multiple combinations, especially together
with flush-mounted dimmers.
-
Do not install the temperature sensor in the area of large electrical consumers (avoid heat
influences).
-
The push button sensor should not be installed in the vicinity of radiators or cooling
systems.
-
The temperature sensor should not be exposed to direct sun.
-
The installation of sensors on the inside of an outside wall might have a negative impact on
the temperature measurement.
-
Temperature sensors should be installed at least 30 cm away from doors, windows or
ventilation units and at least 1.5 m above the floor.
i
Since all parameters are oriented by the room temperature measured by the temperature
sensor, the exact temperature measurement is an essential component of the room
temperature controller.
i
Room temperature measurement by the device is always active, irrespective of the "Room
temperature control" function and can thus be used independently (e.g. for simple
measurement and display of a room temperature without control).
Behaviour in case of sensor faults
The device monitors the integrated, digital, combination sensors cyclically. If communication is
permanently impaired (e.g. due to a sensor or device fault), the corresponding alarm object
"sensor fault" is written with the value "ON" for the error message and a telegram is transmitted
to the bus.
The sensor is deactivated by the device during a fault. Afterwards, an attempt is made to
cyclically reactivate the sensor. If this is achieved reliably after a certain amount of time, the
device resumes measuring the physical values and also resets the sensor fault message by an
"OFF" telegram. In case of an impaired and deactivated sensor, the value "0" is output as
measured value.
i
After a device reset (programming with the ETS, bus voltage return) the objects "sensor
fault" are updated according to the current state and telegrams are transmitted to the bus.
Page 54 of 171
Software "KNX CO2 sensor"
Functional description
