KNX Stack – Medium TP
Twisted Pair is still the most used medium in KNX. The topology of KNX TP is very flexible and can be organized in areas and lines. For the data transfer a balanced baseband signal encoding is used with a data rate of 9600 baud. The nominal bus voltage is 29V DC.
Since KNX TP uses its own physical layer, a dedicated KNX transceiver is required. Today, most devices are based on a KNX UART transceiver, which allows a serial interface with the microcontroller. Although the UART transceiver accepts the physical layer as well as part of the data link layer, the interface has some time restrictions that must be traded through the KNX stack. The address table of the device must be evaluated on receipt, in particular to generate a timely Layer2 Acknowledgment.
The transceiver typically also includes a voltage supply for the application. In most cases, sensors and actuators can be supplied with power via the bus; most network-operated devices require galvanic isolation.
Weinzierl has sold KNX-certified stacks and tools for more than 10 years. While System 7 is still the most widely used implementation, Weinzierl is ready for the next step with the KNX Stack NGS, which provides an optimized implementation of the System B system model.