The DS1100 can be powered through its power jack, pin 9 of the DB9 (RS232) connector, or the optional Power over Ethernet (PoE) module (letter " P" in the model numbering scheme).
Pin 9 input has the same input voltage requirements as the power jack.
The optional PoE module should be powered by 48V (nominal), which is standard for PoE equipment. Your PoE-enabled hub will take care of this. The PoE module outputs 12VDC.
Internally, all three power sources are connected to the DS1100's power regulator through three diodes, as shown in the diagram below.