Glossary A–ZLetter P
Power over Ethernet (PoE)
Power over Ethernet is a method by which a device receives not only data but also its power over the network cable.
It is specified in the IEEE 802.3 family of standards. The power comes from a PoE-capable switch or an injector between switch and device.
In screen networks, PoE is common mainly for small devices: room signs next to meeting rooms, small tablets on doors, some players, sensors and cameras. A single cable is enough, and no socket is needed at the mounting point. This simplifies installation on walls, pillars and doors and allows devices to be restarted remotely via the switch.
Operators should check which power level a device needs and whether the switch can deliver it on each port and in total. The standard levels differ considerably; large displays generally cannot be powered over PoE. As with ordinary Ethernet, cable length is limited to 100 metres. If the switch fails, all devices connected to it go off; a UPS at the switch helps.