The DS1100 can be powered through its power jack, pin 9 of the DB9 (RS232) connector, or the optional PoE module (letter " P" in the model numbering scheme).
Pin 9 input has the same input voltage requirements as for the power jack.
Optional PoE module is supposed to 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 on the diagram below.