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Siemens
Desigo TRA Engineering, mounting and installation
CM111043en_09
Building Technologies
Ethernet network
2016-02-22
* Supply voltage and power depend on the type of PoE switch used and the number of connected room
operator units.
In PoE, power sourcing equipment (PSE) supplies power to powered devices (PD,
here: end devices). Voltage is supplied via the RJ45 plugs and a twisted-pair cable
(TP) to the devices either:
1. Via data transmission lines
2. Or via unused lines of the RJ45 connection.
PoE requires a star topology. Standard PoE switches have between 4 and 16
outputs. In large plants (e.g. different rooms in a hotel) require use of multiple
switches in a line topology.
Further topologies:
Some switches (mostly industrial types) feature an uplink, i.e. multiple switches
can be switched in series.
A single consumer can be supplied via PoE injector, a midspan power source,
contrary to direct sourcing (endspan) via PoE switch.
Standard Ethernet cable
min. category 5
Screened or unscreened
STP / UTP
STP (
S
hielded
T
wisted
P
air) or
UTP (
U
nshielded
T
wisted
P
air)
Distance between switch and room automation station
max. 100 m
Distance between switch and end unit
max. 100 m
Always use switches designed for industrial environment.
Speed 100 Mbit/s or 1 Gbit/s.
Suppliers: e.g. Siemens Scalance, Siemens Ruggedcom.
Required number of outputs
Required power
Operating voltage for switch
(DC 48 V is required for PoE; various switches, however, can be operated on
e.g. DC 18…24 V or AC 230 V
Mounting location (protection class)
Ethernet
PoE
AC 24 V
*
PoE switch
PoE
PoE switch
11
04
3z
2
0
Function
PoE topologies
Specifications
Suppliers
Selection criteria