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8 Appendix
8.1 General information about KNX RF
As with KNX TP, KNX RF also distinguishes between Standard and Easy mode.
The standard mode is called "KNX RF1.R S mode". The carrier frequency is 868.3 MHz. This
relatively low frequency offers excellent signal propagation compared to higher frequencies
(Bluetooth: 2.4 GHz or WLAN: 2.4/5 GHz) and a good balance between power consumption and
range. The range in the free field is up to 100 m. Inside buildings, the range depends on
structural factors and conditions.
The structural conditions and distances between the radio products must already be taken into
account when planning the electrical installation. The radio signals are mainly dampened by e.g.
concrete components with steel reinforcement or metal components. The more dampening
components between transmitter and receiver and the greater the distance, the more critical for
the radio communication. For a system with TP and RF lines, the placement of the media coupler
must be planned as much in the center as possible.
Furthermore, the frequency range used by KNX RF is not exclusively available to KNX. This
means other radio systems might also be in a building and influence the KNX RF communication
(e.g. garage door drives, alarm systems, weather stations, etc.).
Other devices, such as ballasts and lamps, can also be potential sources of interference for
KNX RF systems due to the emission of electromagnetic waves.
The ETS app KNX RF Field Strength Analyzer from Tapko Technologies GmbH shows the
receiving field strength of selected KNX RF products and can support start-up and
troubleshooting.
In ETS 5, the "RF" transmission medium can be selected for a line. The KNX RF products are
included in this line. For each line with "RF" medium, the ETS generates a unique domain
address. The KNX RF products added in the RF line are assigned to this domain address. This
ensures that pieces of information from neighbouring KNX RF lines will not influence each other.
Only devices with the same domain address communicate with each other. The domain address
is automatically transmitted by the ETS when programming the KNX RF products. An RF line can
have a maximum of 256 devices (addresses 0...255). If the system consists of several RF lines or
a combination of TP and RF media, the first device in the RF line is always a media coupler with
the physical address x.x.0 (e.g. 1.2.0). The media coupler transmits the information across lines
via the TP medium. KNX RF products are easy to recognise in the ETS product catalogue due to
the specific radio symbol.
Flush-mounted dimming actuator DU 1
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