PoE, or Power over Ethernet, delivers power and data in one cable, so equipment doesn't require a separate cable for each need. For equipment that does not already have a power or data connection, PoE can be attractive when the power demand is modest. For example, PoE is useful for IP telephones, wireless access points, cameras with pan tilt and zoom, and remote Ethernet switches. PoE can provide long cable runs up to 330 ft and deliver 12 W of isolated power.
PoE technology follows the IEEE 802.3af and 802.3at standards. These standards dictate how equipment needs to work in order to achieve interoperability.
Depending on the application, Depending on the application, PoE-enabled systems are more cost-effective and efficient.
Some of the advantages of PoE equipment over other technologies may be:
The Universal Serial Bus (USB) provides both data and power, but it is designed for short network cables with a maximum length of 16 ft and provides less than 2.5 W of not isolated power. It is less expensive than PoE, and works well for low power peripherals such as a computer mouse, a headset/microphone, or a serial port. Some peripherals, such as speakers, scanners and printers, need more power than USB can provide.
IEEE 1394 (FireWire) is similar to USB but can provide substantially more power (45 W) at a distance of slightly over 14.5 feet. On the other hand, USB peripherals can operate using very little power; while maintaining an Ethernet connection uses a significant amount of power, Thunderbolt specifies up to 10W per port.
If a device already has power available but no data link, then PoE may not be attractive. A wireless data connection such as IEEE 802.11 may be more economical than running a data cable for the device. Alternatively, there are power line communication technologies that can use power cables for transmitting data. Using some power line modems may be more economical than running a cable.
When data rate and power requirements are both low, other approaches may be viable. Mobile phones, for example, use batteries for power and antennas for communication. Remote weather sensors use very low data rates, so batteries (sometimes supplemented with solar power) and custom wireless data links are used.
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