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APPENDIX (B): POWER OVER
ETHERNET
The Power over Ethernet (PoE) is designed to extract power from a conventional
twisted pair Category 5 Ethernet cable, conforming to the IEEE 802.3af Power-over-
Ethernet (PoE) standard.
IEEE 802.3af allows for two power options for Category 5 cables.
The IEEE 802.3af-2003 standard allows up to 15.4 W of power the device. However,
12.95W is the available power, as some power gets lost in the cable. The updated
IEEE 802.3at-2009 (PoE+) standard allows up to 25.5 W (Max 34.2 W) of power the
device.
PoE has advantages over conventional power in such places where AC powers cannot
be reached or expensive to wire.
Note: For proper activation of 12V PoE, the Category 5 cable must be shorter than
140m and conform the PoE standard.
PoE compatibility
With non-Power Sourcing Equipment (PSE)
When it is connected with non PSE, the power adaptor should be connected.
With power adaptor
Connecting both PSE and power adaptor does not do any harm to the product, but
power adaptor will be the only power source for the device as it has priority over PSE.
In this case, disconnecting power adaptor while it is operating will cause the device to
reboot. And PoE will be the power source for the device after the reboot.