There are several options for powering the system.
1) AC Adapter / Wall-wart:
Connect power supply to one unit, TX2 or RX2.
Connect units using CAT-5/6/7 vis HDBT Ports on both side.
Both units should now be powered.
2) Use PRO Adapter or POE switch:
Connect POE to LAN1 on either side.
Connect units using CAT-5/6/7 via HDBT ports on both sides.
Both units should now be powered up.
If POE has ethernet, then ethernet is now available on the other 3 LAN ports.