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.