User Manual

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Siemens Desigo Desigo Room automation - Engineering, mounting and installation CM111043en_14

Smart Infrastructure Ethernet network 2020-10-30

* 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 (Shielded Twisted Pair) or

UTP (Unshielded Twisted Pair)

· 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

Function

PoE topologies

Specifications

uppliers

Selection criteria