What are the Differences Between Passive and Active PoE?

If your device uses 802.3af or 802.3at it is considered to use active POE.  What that means is that the PoE device (Camera/Radio/Telephone/etc.) will check the power coming in and if it doesn’t meet the device requirements it won’t power up.  802.3af/at does a handshake between the sending and receiving POE devices and won’t power up if the receiving device doesn’t provide the proper acknowledgment. 802.3 af/at PoE voltage will always be 44 to 57 volts DC.

-Passive POE usually refers to any device using POE to power that is not 802.3af/at.

-This includes things like cameras and radio antennas that run on 18-48V DC PoE.

-Passive POE does not do a handshake, so it is extremely important to know what POE voltage your device requires before plugging in the CAT5 cable and powering it up.

NOTE: If you connect the wrong voltage, you can easily burn up your device.