The Four Different Types of Installation
There are 4 communication mediums within the KNX protocol and as they all work using the same standardised datapoint types, they can be coupled together as needed. Additional data is added for IP, RF and Powerline to ensure security and reliability given the open nature of these mediums.
The most common protocol, running over a dedicated cable. The installation is broken down into segments with each supporting 64 devices. These can be linked together into lines, areas or backbone using a line coupler, which is configured to manage the flow of communications ensuring reliable communication.
There are two forms of IP in KNX. The first is a direct gateway for commissioning and interfacing. The second is true KNX over IP, which allows for any line segment in KNX to be based on IP. This could be used to link areas of a building together or for a KNX IP device to form part of the system.
Although part of the KNX specification for many years, only recently has it been made possible to use RF devices as part of a wider KNX installation. KNX RF uses the frequency of 868mhz to ensure good transmission inside buildings, along with advanced encoding to ensure messages are able to be decoded correctly even when interference is present.
Uses the mains cabling as a medium, superimposing control signals signal over the standard 50/60 HZ waveform to send the standardised KNX messages. Again, a long standing part of the KNX specification, however, the level of support from manufacturers has been in steady decline with a limited number of products available.