Gira CO2-Sensor, Руководство пользователя

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4.2.4.3.4 Limiting values
Four limiting values can be assigned to the CO
2
measured value and two limiting values to the
humidity measured value. This makes it possible to trigger actions when the adjustable limits
are exceeded or undershot. Thus, if there is a certain CO2 content in the room air, for example,
ventilation can be activated or warning messages generated.
Types of limiting value specification
The value of a limiting value itself can be specified in three ways.
-
Limiting value specification via the parametrization.
This is the value configured in the ETS, which comes into effect after the initialisation or
after a download. This value can be overwritten via an external object or the teaching
function. In this case, the internal value is first reactivated after downloading the project
once again.
- Limiting value specification via an external object.
This external value overwrites permanently the value of the limiting value specification via
the parametrization. In this case, the internal value is first reactivated after downloading the
project once again.
- Limiting value specification via the teaching function.
This function makes it possible to define the current measured value as the limiting value
by pressing an external push-button sensor. This value overwrites permanently the value of
the limiting value specification via the parametrization. In this case, the internal value is first
reactivated after downloading the project once again.
i If the internal value of the limiting value specification is overwritten by parameterization at
any point, this value will remain lost until a new download is performed via the ETS.
Setting limiting value specification via parametrization
The limiting value specification for the measured values "CO
2
" and "Humidity" are set by means
of the parameters "Limiting value X" in the parameter node "Limiting value X".
"n limiting values active" is set for the measured value on the parameter page "CO2
measurement" or "humidity measurement". There is a maximum of four (n = 1…4) limiting
values available for the CO
2
measured value, and a maximum of two (n = 1…2) for the humidity
measured value.
o Enter the required value in the input field "Limiting value X".
i This value is loaded to the device during initialization and renewed download.
i The set value is retained until it is overwritten by an external value.
Hysteresis of the limiting values
The device has four limiting values for the CO
2
measured value, and two limiting values for the
humidity measured value. Each limiting value has an adjustable hysteresis and a definition of
the response when the value is exceeded or undershot. The hysteresis itself serves to prevent
frequent switching backwards and forwards when there is a measured value in the approximate
area of the limiting value. This, for example, prevents a fan from constantly being switched on
and off. The hysteresis values should therefore be chosen as large as possible. These
circumstances are explained in the following diagrams.
Page 58 of 171
Software "KNX CO2 sensor"
Functional description