Siemens IEEE802.11 Instrucciones de operaciones descargar pdf (Pagina 25)

Description

2.7 Power over Ethernet (PoE)

SCALANCE W770/W730 to IEEE 802.11n Web Based Management

Configuration Manual, 11/2014, C79000-G8976-C323-03

Cable used for the power supply

●

Variant 1 (redundant wires)

In Fast Ethernet, the wire pairs 1, 2 and 3, 6 are used to transfer data. Pairs 4, 5 and 7, 8

are then used to supply power. If there are only four wires, the voltage is modulated onto

wires 1, 2 and 3, 6 (see variant 2). This alternative is suitable for a data transmission rate

of 10/100 Mbps. This type of power supply is not suitable for 1 Gbps because with gigabit

Ethernet, all 8 wires are used for the data transmission.

●

Variant 2 (phantom power)

With phantom power, the power is supplied over the pairs that are used for data transfer,

in other words, all eight (1 Gbps) or four (10/100 Mbps) wires are used both for the data

transfer and the power supply.

Whether a device supports variant 1 and variant 2 or only variant 2 can be found in the

operating instructions of the relevant device.

A PoE-compliant switch can supply the end device either using:

● Variant 1 or

● Variant 2 or

● Variant 1 and variant 2.

Endspan

With endspan, the power is supplied via a switch that can reach a device over an Ethernet

cable. The switch must be capable of PoE, for example a SCALANCE X108PoE,

SCALANCE X308-2M POE, SCALANCE XR552-12M.

Midspan

Midspan is used when the switch is not PoE-compliant. The power is supplied by an

additional device between the switch and end device. In this case, only data rates of 10/100

Mbps can be achieved because the power is supplied on redundant wires.

A Siemens power insert can also be used as the interface for the power input. Since a power

insert supports a power supply of 24 VDC, it does not conform with 802.3af or IEEE 802.3at.

The following restrictions relating to the use of power inserts should be noted:

WARNING

Operate the power insert only when the following conditions apply:

• with extra low voltages SELV, PELV complying with IEC 60364-4-41

• in USA/CAN with power supplies complying with NEC class 2

• in USA/CAN, the cabling must meet the requirements of NEC/CEC

• Power load maximum 0.5 A.

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Siemens IEEE802.11 Instrucciones de operaciones Pagina 25