Operating modes - Basic Documentation - RDF302 - RDF302.B - RDF302/VB

Semi-flush mount room thermostats with RS485 Modbus communications RDF302, RDF302.B, RDF302/VB

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Thermostats (temperature controller with sensor)
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Technical Documentation > Basic Documentation
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The thermostat's operating mode can be influenced in different ways. e.g. operating mode button, switch over contact, Modbus, etc. Specific heating and cooling setpoints are assigned to each operating mode.

Room operating mode: Preselection

The operating mode can be selected via Modbus.

  • If a bus command is received via MODBUS for either COMFORT or ECONOMY operating mode, the symbol of the selected operating mode will be displayed.
    i.e. either COMFORT or ECONOMY symbol only

  • If a bus command is received for PROTECTION mode, the AUTO TIMER symbol (RDF3xx_auto.png) will be displayed and all key buttons will be de-activated.

i.e. both PROTECTION and AUTO TIMER symbols

Modbus Room
operating mode: State

The thermostat returns the effective room operating mode on the Modbus.

The following operating modes are available:


In Comfort mode, the thermostat maintains the Comfort setpoint. This setpoint can be defined via parameters P8, P9 and P10.

Also, it can be locally adjusted via the +/- buttons or remotely via Modbus.

In Comfort mode, the fan can be set to automatic or manual fan speed: Low, medium or high.


A preset setpoint in economy mode can be defined via parameters P11 and P12.

The thermostat switches to Economy mode when...

Window state

  • the operating mode button is pressed (only possible if parameter P02 is set to 2)

  • Economy is sent via Modbus

  • an operating mode switchover contact (e.g. keycard contact presence detector, window contact) is active.
    The contact can be connected to multifunctional input X1, X2.
    Set parameter P38 / P40 to 3 (P02 is irrelevant) *)

  • "Window state" is sent via Modbus


*) Operating mode switchover: Only one input source must be used, either local input X1/X2 or Modbus.
User operations are ineffective and “OFF” is displayed if the operating mode switchover contact is active, or if "Window state" is sent via Modbus. The parameters related to X1 and X2 input functions are not applicable to RDF302.B.


In Protection mode, the system is...

  • protected against frost (factory setting 8 °C, can be disabled or changed via P65)

  • protected against overheating (factory setting OFF, can be enabled or changed via P66)

No other operating mode can be selected locally if Protection mode is commanded via Modbus. is displayed.