What object flags are defined with KNX?

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.