What object flags are defined with KNX?

To what purpose do the KNX object flags serve, what types are there and how are they defined?

val / enthusiast (115)


With KNX, the object flags are defining the bus behavior of the representing object, thus each of them is defined with one of the 6 different flags:

  • C: Communication flag
  • R: Read flag
  • T: Transmit flag
  • W: Write flag
  • U: Update flag
  • I: Initialization flag

The Communication flag (C-flag)

This flag represents that all of the defined flags are enabled for this object.

The Read flag (R-flag)

A device carrying this flag will react to the GroupValueRead telegram that is coming from a bus, thus sending back to the bus a GroupValueRead telegram.

The Transmit flag (T-flag)

A device with a T-flag object can transmit any object value, for example sending a GroupValueWrite telegram to the bus. A push-button object representing this means that this object has been manipulated.

The Write flag (W-flag)

This device object reacts back to a GroupValueWrite coming from the bus, meaning it will overwrite the object value. For a switch actuator, for example, this might mean that a certain relay representing these objects will be opened or closed.

The Update flag (U-flag)

A device with this object reacts to a GroupValueResponse telegram, capable of overwriting the object values.

The Initialization flag (I-flag)

This object will reset send a GroupValueRead telegram back to the bus, with the purpose to get the object value via a GroupValueResponse. One of the reasons it might be a power failure, bus or device reset requires via a telegram.

sonny-s / enthusiast (262)

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