Data Sheet for Product

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Siemens RDF302… Flush-mounted room thermostats with RS485 Modbus communications CE1N3079en
Smart Infrastructure 2020-02-21
Cables of SELV inputs X1-M / X2-M: Use cables with min 230 V insulation, as the
conduit box carries AC 230 V mains voltage.
Inputs X1-M or X2-M: Several switches (e.g. summer / winter switch) may be
connected in parallel. Consider overall maximum contact sensing current for
switch rating.
Isolate the cables of Modbus communication input +, - and REF for 230 V.
No cables provided with a metal sheild.
Disconnect from supply before opening the cover.
Commissioning notes
The room thermostats are delivered with a fixed set of applications.
Select and activate the relevant application during commissioning using one of the
following tools:
- Local DIP switch and HMI
- Modbus commissioning tools
Set the DIP switches before snapping the front panel to the mounting plate, if you
want to select an application via DIP switches.
All DIP switches need to be set to “OFF” ("remote configuration"), if you want to
select an application via commissioning tools.
After power is applied, the thermostat resets and all LCD segments flash,
indicating that the reset was correct. After the reset, which takes about 3 seconds,
the thermostat is ready for commissioning by qualified HVAC staff.
RDF302.B does not have input X1 and X2.
If the “NONE” displays on the LCD, it means that the DIP switches was set to OFF-
OFF for remote configuration, but the application had not yet assigned to the
device. The application can be set by commissioning tools via the RS485 Modbus.
Each time the application is changed, the thermostat reloads the factory setting for
all control parameters, except for baud rate (P68), parity (P70) and zone addresses
(P81)!
The thermostat's control parameters can be set to ensure optimum performance of
the entire system.
The parameters can be adjusted using
- Local HMI
- Modbus commissioning tools
The control sequence may need to be set via parameter P01 depending on the
application. The factory setting for the 2-pipe application is “Cooling only”; and
“Heating and Cooling” for the 4-pipe application.
When the thermostat is used with a compressor, adjust the minimum output on-
time (parameter P48) and off-time (parameter P49) for Y11/Y21 to avoid damaging
the compressor or shortening its life due to frequent switching.
Recalibrate the temperature sensor if the room temperature displayed on the
thermostat does not match the room temperature measured (after minimum 1 hour
of operation). To do this, change parameter P05.
We recommend to review the setpoints and setpoint ranges (parameters
P08…P12) and change them as needed to achieve maximum comfort and save
energy.
Application
s
Display “NONE”
STOP
Note
Control parameter
s
Control sequence
Compressor-based
application
Calibrate sensor
Setpoint and range
limitation