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Siemens
Desigo TRA Engineering, mounting and installation
CM111043en_09
Building Technologies
KNX PL-Link room bus
2016-02-22
12.5 Technical data KNX PL-Link
Transmission medium (bus cable)
TP (twisted pair)
Baud rate
9.6 kbps
(fixed for TP)
Bus line polarity
PL+, PL–
(not interchangeable)
Bus terminating resistor
Not required
The communication signal (information) is transferred symmetrically, i.e., as
voltage difference between the two bus lines (and not as a voltage difference to the
earthing potential). The sign preceding the voltage between PL+ and PL–
determines signal values 0 and 1.
Cable type
2-wire, stranded (
one wire pair)
or 2x2-wire, stranded
or spiral quad
Wire diameter
Min. 0.8 mm (AWG20)
Max. 1.0 mm (AWG18)
Line resistance
20 … 75 /km
Specific capacity
10 …100 nF/km at 10 kHz
Specific inductivity
450 …850 µH/km at 10 kHz
Screens
Not required
PXC3 devices do not have a connection for bus cable screens
Internal bus power from room automation station
PXC3... DC 30 V, 160 mA for max. 16 KNX devices with 10 mA each
DXR2... DC 30 V, 50 mA for max. 5 KNX devices with 10 mA each
If the consumption is more than 160 / 50 mA (more than 16 / 5 devices or more
than 10 mA per device), one or two external bus power supplies are required.
In this case the internal bus power supply must be disabled via tool, as parallel
operation of the internal supply with external supplies is not admissible.
64 devices in a KNX PL-Link network.
KNX bus
Communication signal
KNX bus cable
Note
Bus power supply
Max. number of devices
