Temperature Measurement; Internal Temperature Recording; External Temperature Recording; Monitoring - ABB i-bus KNX Product Manual

4.2 Temperature
measurement
4.2.1 Internal temperature
recording
4.2.2 External temperature
recording
4.2.3

Monitoring

© 2009 Busch-Jaeger Elektro GmbH – A Company of the ABB Group
The ambient temperature controller with display can record the temperature
with an internal sensor. Values can also be received from an external sensor
or an outside temperature sensor via communication objects. Receipt of
the values can be monitored and possibly calibrated. The functions are
explained in more detail below.
The device has an internal temperature sensor. The measured value is sent
to the controller as a current value. The value is also shown on the display
at the same time ("display in normal operation": "current actual value").
The measured temperature can also be sent over the bus with the 2-byte
communication object "send current value - temperature sensor" to, for
example, display as a visualisation. The transmission is done depending on
the parameter "send current value on change up" and "send current value
cyclically". Both parameters are disabled by default. This means that if the
current temperature is to be sent, at least one setting must be enabled.
The setting "send current value on change up" has the advantage that even
the smallest changes of the measured temperature, adjustable from 0.1 K
to 1.0 K, are sent over the bus. The disadvantage is that, for example,
the setting 0.1 K and a large number of ambient temperature controllers
in one installation increases the bus load.
The parameter "send current value cyclically" has the advantage that
the current value is sent continuously, even if the measured value does
not change. The disadvantage is that fast changes may not be registered,
because the cycle time has been set too large. However, it should also
not be set too small to prevent excessive bus loading.
In areas such as open plan offices it can be difficult to control
the temperature with only a single ambient temperature controller.
We recommend subdividing such areas into zones with additional
temperature sensors.
The parameter "ambient temperature measurement" must be set to "internal"
and "external" to enable the temperature value of the additional temperature
sensor to be integrated. Then the internally and externally measured
temperatures can also be weighted. The weighting settings depend on
the local conditions. If the ambient temperature controller and the additional
temperature sensor are equally distant from the radiators (flat radiators),
the setting "50%/50%" should give good control results.
The "Monitoring temperature measurement" parameter defines whether
the internal and external temperature sensors are to be monitored. This
means that the ambient temperature controller must receive at least one
telegram with the current temperature on the associated communication
object within a configurable time ("monitoring time for external temperature"
and "monitoring time for outside temperature").
If a telegram is not received within the monitoring time, the ambient
temperature controller will assume that the sensor for the outside
temperature or external temperature is faulty or no longer connected to
the bus.
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