Temperature control - Basic Documentation - RDF600KN - RDF600KN/S - RDF600KN/VB

Semi-flush mount room thermostats with KNX communications RDF301, RDF301.50, RDF301.50H, RDF600KN, RDF600KN/VB, RDF600KN/S

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Desigo PX Open
Desigo Open
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Thermostats (temperature controller with sensor)
Building automation
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Technical Documentation > Basic Documentation
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General note: Parameters

Setting of the control parameters (P01, etc., mentioned throughout the document) is described in section 3.13.

Temperature control

The thermostat acquires the room temperature via built-in sensor, external room temperature sensor (QAA32), or external return air temperature sensor (QAH11.1), and maintains the setpoint by delivering actuator control commands to heating and/or cooling equipment. The following control outputs are available:

  • ON/OFF control (2-position)

  • Modulating PI/P control with 3-position control output (only for 2-pipe applications)

The switching differential or proportional band is 2 K for heating mode and 1 K for cooling mode (adjustable via parameters P30 and P31).
The integral action time for modulating PI control is 5 minutes (RDF301...) and 45 minutes (RDF600KN, RDF600KN/VB), adjustable via parameter P35.


The display shows the acquired room temperature or the Comfort setpoint, selecta­ble via parameter P06. The factory setting displays the current room temperature.
Use parameter P04 to change the room temperature display from °C to °F as needed.

Room temperature

The acquired room temperature (internal or external sensor) is also available as information on the bus.


  • With automatic changeover or continuous heating / cooling, symbols / indicate that the system currently heats or cools (heating or cooling output is activated).

  • With manual changeover (P01 = 2), symbols / indicate that the system currently operates in heating or cooling mode. Thus, the symbols are displayed even when the thermostat operates in the neutral zone.

Concurrent display of
°C and °F

Concurrent display of the current temperature or setpoint in °C and °F (parameter P07 = 1) is possible on the thermostats.

Outside temperature via bus

The outside temperature can be displayed on the room thermostat by setting parameter P07 = 2. This temperature value has only information character.

In LTE Mode, the outside temperature can only be received on outside temperature zone 31.
In S-Mode, the corresponding communication object needs to be bound with a KNX sensor device.

Time of day via bus

Time of day via bus can be displayed on the room thermostat by setting parameter P07 = 3 or 4. The display format is either in 12- or in 24-hour format.
The information can be received from a Synco controller with time master functionality or any other KNX device if the corresponding communication object is bound.


  • When an application program is downloaded to the Synco devices via ETS, the correct group addresses need to be downloaded as well to display the time of day on the room thermostat (see Synco Knowledge Base - KB771).