Description
3.2 Power over Ethernet (PoE)
SCALANCE X-300M PoE
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Compact Operating Instructions, 05/2016, A5E02630810-09
3.2
Power over Ethernet (PoE)
Power over Ethernet (PoE)
With PoE, the power for networked devices is carried via Ethernet. Here, there are two
methods of supplying power:
●
Alternative A
Here, the voltage is transferred on the data wires 1, 2, 3 and 6 of the Ethernet cable
Requirements for the Ethernet cable:
–
For 10Base-T/100Base-TX, a 4-wire cable is adequate for data transmission and
power supply.
–
With 1000BASE-T, an 8-wire cable is necessary for data transmission.
●
Alternative B
Power is transferred on the free wires 4, 5, 7 and 8 of the Ethernet cable.
Requirements for the Ethernet cable: For 10Base-T/100Base-TX/1000BASE-T, an 8-wire
cable is needed.
PoE-compliant devices can be divided into the following groups:
●
PSE - power sourcing equipment
These inject power onto the Ethernet cable.
●
PD - powered devices
These are supplied with power via Ethernet.
The PoE ports of the switch
As a PSE, the X308-2M PoE supplies PoE-compliant devices with power over Ethernet. The
48 V power required to supply the powered devices is generated internally on the switch, no
extra power supply unit is necessary.
The X308-2M PoE uses the "alternative A" for this. Per RJ-45 port, a maximum of 15.4 W
are available for supplying a PoE-compliant device. If a Cat5/Cat5e cable with a maximum
length of 100 m is used, the connected device can be supplied with a power of 12.95 W.
Note
The total power provided by the SCALANCE X308-2M PoE on all four PoE ports is a
maximum of 30.8 W.
The PoE ports meet the conditions listed in the IEEE 802.3af / IEEE 802.3at standard
(type 1) for environment A , in other words power supply over Ethernet within a power supply
system. For details of configuring and enabling PoE for individual ports, refer to the
configuration manual SCALANCE X-300 / X-400 on the accompanying CD.
