Application mode - 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

Product Family
Desigo Open
Desigo PX Open
Product Group
Building automation
Thermostats (temperature controller with sensor)
Content Language
English
Content Type
Technical Documentation > Basic Documentation
Product Version
Status
Valid
Date
2020-02-21
Document No
CE1P3171en
Download ID
A6V10385333
Stock No.
S55770-T293
S55770-T400
S55770-T430
Product No.
RDF600KN
RDF600KN/S
RDF600KN/VB
Access level
Internet
File Type
html

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Application mode

The behavior of the thermostat can be influenced by a building automation and control system (BACS) via bus with the command "Application mode".
With this signal, cooling and/or heating activity can be enabled or disabled. Application mode is supported in LTE Mode and S-Mode.

The RDF KNX thermostats support the following commands:

# Application mode Description Control sequence enabled
0 Auto Thermostat automatically changes between heating and cooling Heating and/or cooling
1 Heat Thermostat is only allowed to heat Heating only
2 Morning warm-up If "Morning warm-up" is received, the room should be heated up as fast as possible (if necessary). The thermostat will only allow heating Heating only
3 Cool Thermostat is only allowed to provide cooling Cooling only
4 Night purge Not supported by fan coil applications N/A (= Auto)
5 Pre-cool If "Pre-cool" is received, the room should be cooled down as fast as possible (if necessary). The thermostat will only allow cooling Cooling only
6 OFF Thermostat is not controlling the outputs, which means all outputs go to off or 0% Neither heating nor cooling
8 Emergency heat The thermostat should heat as much as possible. The thermostat will only allow heating Heating only
9 Fan only

All control outputs are set to 0% and only the fan is set to high speed.

Function will be terminated by any operation on the thermostat

Run fan in high speed

With all other commands, the thermostat behaves like in Auto mode, i.e. heating or cooling according to demand.

ACS_Tool_Logo ACS

The state (heating or cooling) of the thermostat can be monitored with the ACS tool (diagnostic value "Control sequence"). The last active mode is dis­played when the thermostat is in the dead zone or temperature control is disabled.

Heating OR cooling

With a 2 pipe application, the control sequence state is determined by the application mode (see section 3.6.3) and by the state of the heating / cooling changeover signal (via local sensor or bus), or fixed according to the selected control sequence (P01 = heating (0) / cooling (1)).

Application mode (via bus) State changeover / conti­nuous heating or cooling Control sequence state
Auto (0) Heating Heating
Cooling Cooling
Heat (1), (2), (8) Heating Heating
Cooling Heating
Cool (3), (5) Heating Cooling
Cooling Cooling

Night purge (4),

Fan only (9)

Heating Heating
Cooling Cooling

Heating AND cooling

With a 4-pipe, 2-pipe with electric heater, and 2-pipe with radiator application, the control sequence state depends on the application mode and on the heating / cooling demand.

Application Mode (via bus) Heating / cooling demand Control sequence state
Auto (0) Heating Heating
No demand Heating / cooling depending on last active sequence
Cooling Cooling
Heat (1), (2), (8) Heating Heating
No demand Heating
Cooling Heating
Cool (3), (5) Heating Cooling
No demand Cooling
Cooling Cooling
Night purge (4),
Fan only (9)
No temperature control active Heating / cooling depending on last active sequence

The value of the output as a function of the room temperature is shown in the following diagram in case of a heating and cooling system:

Wheat = current heating setpoint

Wcool = current cooling setpoint