RDU20U, RDU50U and RDU50.2U Room Temperature Controllers
Technical Instructions
with LCD for Heating and Cooling Systems
Document Number 155-735
November 1, 2006
Siemens Industry, Inc.
Page 5
Energy Saving Mode
A changeover switch can be connected to the dry contact (D1
–GND). When the switch
closes its contact (due to an open window, for instance), the operating mode will
change from normal operation to Energy Saving mode. In this operating mode, the
heating or cooling setpoints are maintained (setting of control parameters P01 and
P02). If the Energy Saving mode setpoints are set to OFF, the controller will turn OFF
when the switch closes its contact.
When activated, the status input (D1
–GND) overrides the
RDU20U/RDU50U/RDU50.2U setpoints as follows:
•
Heating Mode
→ Parameter 01 becomes active
•
Cooling Mode
→ Parameter 02 becomes active
•
OFF
→ No effect
Mechanical Design
•
The unit consists of two parts:
−
Plastic housing
−
accommodates the electronics, the operating elements, and
the built-in room temperature sensor.
−
Base plate
−
houses the wire terminations.
•
The housing engages in the controller base and is secured with two screws.
•
The screw terminals are mounted on the base plate.
•
The DIP switches are located on the circuit board, which is accessible through the
rear of the housing. To access the DIP switches, remove the housing from the base
plate. See Figure 9.
Figure 9. DIP Switch Setting.
Table 3. RDU20U DIP Switches.
DIP Switch No.
Description
Position ON
Position OFF
1
LCD display
Room (return air)
temperature
Setpoint
*
2
Control Algorithm
3-P modulating PI
control
*
ON/OFF control
3
Not used
4
Temperature scale
Fahrenheit
*
Celsius
Table 4. RDU50U and RDU50.2U DIP Switches.
DIP Switch No.
Description
Position ON
Position OFF
1
LCD display
Room temperature
*
Setpoint
2
0 to 10 Vdc output logic
Cooling
– RA
Heating
– RA
Cooling
– DA*
Heating
– DA
3
Not used
N/A
N/A
4
Temperature scale
Celsius
Fahrenheit
*
* Factory setting
