User Manual

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Siemens RDF302 Basic documentation CE1P3079en
Smart Infrastructure 2020-12-01
3.9 Multifunctional input, digital input
The thermostat has 2 multifunctional inputs X1 and X2. RDF302.B does not have
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).
Heating / 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.
Diagnostic 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