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Siemens RDF302 Basic documentation CE1P3079en
Building Technologies 07 Dec 2011
3.9 Multifunctional input, digital input
The thermostat has 2 multifunctional inputs X1 and X2
An NTC type sensor like the QAH11.1 (AI, analog input) or a switch (DI, digital
input) can be connected to the input terminals. The functionality of the inputs can
be configured via parameters P38 + P39 for X1 and P40 + P41 for X2.
The current temperature or state of the inputs X1/X2 is available on Modbus for
monitoring purposes.
The parameters can be set to the following values:
# Function of
input
Description Type
X1/X2
0 Not used No function. --
1 External / return
air temperature
Sensor input for external room temperature
sensor or return air temperature sensor to
acquire the current room temperature, or
floor heating temperature sensor to limit the
heating output.
Note: The room temperature is acquired by
the built-in sensor if the floor temperature
limitation function is enabled via parameter
P51.
AI
2 Heating / cooling
changeover
Sensor input for “Automatic heating / cooling
changeover” function.
A switch can also be connected rather than a
sensor (switch closed = cooling, see section
3.5).
Heatin
g / cooling changeover is also possible
via Modbus. In this case, the function must
not be assigned to any local input X1, X2.
See also section 3.5.
Diag
nostic value 0 ˚C is displayed for closed
contact / 100 ˚C for open contact, if a switch
is connected.
AI / DI
3 Operating mode
switchover
Digital input to switch over the operating
mode to Economy.
If the operating mode switchover contact is
active, user operations are ineffective and
“OFF” is displayed.
Operating mode switchover is also possible
via Modbus. In this case, the function must
not be assigned to any local input X1, X2.
See also section 3.2.
DI
4 Dew point monitor Digital input for a dew point sensor to detect
condensation. Cooling is stopped if
condensation occurs.
DI
X1 input
X2 input
Heating / cooling
changeover
Window state
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