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Siemens Desigo Desigo Room automation - Engineering, mounting and installation CM111043en_13
Smart Infrastrructure KNX PL-Link room bus 2020-04-30
13 KNX PL-Link room bus
· The KNX PL-Link bus must be inside the building.
The cables must never leave the building.
· The KNX PL-Link bus facilities communications from the PXC3 room automation
station to a maximum 64 devices on the KNX bus devices for various
manufacturers.
· Note: The number of devices is also limited by the number of data points and the
available bus power.
Bus power is incremented during engineering with the ABT tool.
· The KNX PL-Link bus basic version comprises one cable and two stranded bus
wires.
· The PXC3 has one internal bus power supply of 160mA.
· The DXR2 has one internal bus power supply of 50mA.
· The PXC3 also includes an AC 24 V / 2A output for devices with increased
power consumption that is supplied via AC 24 V rather than via the KNX PL-Link
bus.
· The KNX PL-Link is physically based on the KNX bus (Konnex).
· In KNX networks area/line couplers and IP routers are not allowed.
· Interconnection of room automation stations via KNX PL-Link is not admissible;
the connection is done exclusively via Ethernet switches (Section 9) or MS/TP
section 10).
· The polarity of the KNX PL-Link bus conductors must be correct.
(KNX terminals + and –).
In most countries, specific /KNX know-how is transmitted through training centers
certified by the EIBA / KNX association (see www.eiba.com or www.knx.org)
13.1 Bus power supply
A bus power supply is required for KNX bus communications. Throttled voltage DC
29 V is used.
13.1.1 Internal KNX PL-Link power supply
The room automation stations have an internal bus power supply, which is
switched on by default.
DXR2: 50 mA to supply approx. 5 KNX PL-Link devices
PXC3: 160 mA to supply approx. 16 KNX PL-Link devices
If an external supply is used, the internal supply must be switched off
manually via tool, as parallel operation is not permitted.
DXR2: If third-party KNX devices are integrated, we recommend switching off the
internal bus power supply via tool and using an external bus power supply.