Tycon Power TP-DCDC-1248M Power over Ethernet Injector - 12 V DC, 24 V DC Input - 48 V DC, 500 mA Output - 10/100/1000Base-T Input Port(s) - 10/100/1000Base-T Output Port(s) - 24 W

The TP-DCDC Series of DC to DC converters offered by Tycon Power Systems are a low cost and high reliability solution for those requiring 18V to 48VDC Power Over Ethernet voltage from a 12 or 24V battery system. They have an integrated POE injector to apply the 48VDC to the CAT5 Ethernet cable. The output is regulated 18V, 24V or 48VDC from an input voltage between 9VDC and 36VDC. They have two isolated inputs for connecting 2 power sources, like a primary and backup power source. A metal enclosure model is available for industrial applications.

They accept data-in to a shielded RJ45 Jack and provide data-out and POE power on the shielded RJ45 output jack.
They work by supplying power on the unused Ethernet pins 4,5(V+) and 7,8(V-). An IEEE 802.3af compliant model is
available for those applications requiring 802.3af handshake.

They have various protections for surge, short circuit and overload. The units have power output up to 24W.