Main Group (0-31):
Middle Group (0-7):
Group Address (0-255):
Telegram Transmission Process
T1 Pause: The time before a new telegram starts transmitting on the bus after it's idle.
T2 Pause: The time after the telegram is sent, during which devices verify reception.
Acknowledgment: Devices acknowledge receipt of the telegram.
KNX Power Supply and Its Integrated Choke
In a KNX system, the power supply is essential for delivering both the operating voltage and communication signals across the bus. A key component of this is the integrated choke, which ensures that the system works efficiently for both powering devices and transmitting data.
The KNX bus sends data as logical 1s and 0s:
A logical 1 is represented by a steady bus voltage of approximately 30V DC.
A logical 0 causes the bus voltage to drop temporarily by about 5 volts.
The choke reacts to these voltage drops almost instantaneously. It uses its inductive properties to quickly correct the drop and restore the voltage back to 30V DC, ensuring smooth communication on the bus.
With a communication rate of 9600 bits per second, the choke must stabilize the voltage within 104 microseconds for each bit. This clever design allows KNX systems to reliably handle both power delivery and data transmission on the same wires.
Timing Information
Telegram Structure Explanation
Header (6 bytes)
Byte 0
Control Field
Byte 1
Source Address High byte (Area + Line)
Byte 2
Source Address Low byte (Unit)
Byte 3
Destination Address High byte (Main address + middle address)