A PoE system comprises a PSE (Power Sourcing Equipment)and a PD (Powered Device).
The PSE may either be an End-span (i.e. a layer 2 Ethernet Switch with integrated PoE) or a mid-span, while the PD is a PoE-enabled terminal, such as IP phone, Wireless LAN access pointand Network Security Camera.
The PoE Tester check your RJ-45 outlet for power and identify its source, Midspan or Endspan, i.e. IEEE 802.3af standard compliantMidspans/Switches and Cisco pre-standard Proprietary In-line Switches.