Guide

#Concepts

A diagram separates user actions, KNX communication, actuator outputs, and connected equipment.

button press → device behavior → communication object → bus telegram
                                                  ↓
                                  receiving object (W flag)
                                                  ↓
                         behavior → output → lamp or shutter

#Device

A KNX device has an individual address such as 1.1.10. It contains communication objects and may also have buttons, inputs, and channels. Its behavior defines its logic, for example pushButton/v1, switchActuator/v1, shutterActuator/v1, daliGateway/v1, roomThermostat/v1, or a registered extension. The kind field classifies the device and determines its representation.

#Communication object

Each object has a value, a DPT that determines how to interpret it, one or more group addresses, and flags:

Flag	Enabled	Disabled
`C` communication	Always enabled in this model.	—
`W` write	A received write updates the value and invokes the behavior.	The telegram remains visible, but the value and behavior do not change.
`T` transmit	The object can send its value.	The value may change locally, but no telegram is sent.
`R` read	The object responds to a read on any of its addresses, on its sending address.	No response is sent.
`U` update	A received response updates the object.	Responses are ignored.

R and U are optional in JSON; see their defaults in the USB interface guide. The object's port (switch, status, move, and so on) gives it a role in its behavior; see the port reference.

#Group address and telegram

A group telegram has a source individual address, a destination group address, a service, and—on a write or response—payload data. The DPT is not transmitted: each device interprets the payload using its own object DPT. Every device on the line can receive the telegram, but only objects associated with its destination address process it.

Service	Sent by	Processed by
`GroupValueWrite`	A behavior with the T flag, or the USB interface panel.	Associated objects with the W flag.
`GroupValueRead`	The USB interface panel.	Associated objects with the R flag; each responds on its sending address.
`GroupValueResponse`	An object answering a read.	Associated objects with the U flag.

#Channel and connected equipment

A channel is an actuator output, such as a relay or motor drive. Its behavior sends commands such as on/off or up/down/stop. Connected equipment, such as a lamp or shutter, responds to those commands and has its own physical state. It does not know about group addresses or DPTs.

The separation makes it possible to show a miscalibrated shutter: the actuator estimates position using its configured travel time while the connected shutter moves at its actual speed.

#Internal association

When an object transmits, other objects in the same device that share the address may also receive the telegram if their W flag permits it. A status object can therefore control another output of the same actuator. This convention of the model is not implemented identically by every manufacturer.