Ethernet - Siemens SIMATIC NET SCALANCE W774-1 Operating Instructions Manual

Power over Ethernet
The two following variants are available for power supply via an Ethernet cable:
• IEEE 802.3at type 1 (IEEE 802.3af)
On an 8-wire Fast Ethernet cable, the power is supplied via the free data wires 4, 5, 7
and 8. This corresponds to alternative B according to IEEE 802.3af.
• IEEE 802.3 at type 2
The power supply is known as phantom power via the wire pairs carrying signals (1/2
and 3/6).
The SCALANCE W774/W734 RJ-45 devices support the standards IEEE 802.3at type 1
(IEEE 802.3af ) and IEEE 802.3.at type 2.
Note
Disabling the PoE power supply
Before you pull a plug via which the device is supplied with power using PoE, disable the
relevant PoE power supply.
Note
"Phantom power" only with SCALANCE W774 M12 EEC
The SCALANCE W774 M12 EEC device only supports the standard IEEE 802.3 at type 2.
With this device, the attachment to Ethernet is only possible using four-wire cables. For
this reason, no PSE (Power Sourcing Equipment) can be used that only supplies the
power via the free wire pairs.
Ethernet cables with M12 connectors for the SCALANCE W788-x M12 (Gigabit Ethernet,
eight-wire) cannot be used for the SCALANCE W774 M12 EEC.
Note
No power sourcing equipment (PSE)
The SCALANCE W774/W734 devices cannot be used as a PoE power supply for other
devices.
5.3

Ethernet

The SCALANCE W774/W734 devices have two Ethernet interfaces located on the
underside of the device. Depending on the version, either RJ-45 or M12 sockets are
available.
SCALANCE W774-1 /W734-1
Operating Instructions, 07/2020, C79000-G8976-C325-14
Connection
5.3 Ethernet
41