Many thanks mkx
I have not been able to interact with one of these units, so I am still a little confused. If I interpret your reply correctly, if both the 48 volt supply and the 18 volt supply are simultaneously attached and functioning, the POE outs will ONLY be 48V?
If you plug in both 24V and 48V AC adapters into the device, then it can power 24V and 48V devices simultaneously on different ports. If either adapter fails or comes unplugged, the switch itself will still have power, but any devices that use that voltage that came unplugged will lose all power and not come back until the adapter is replaced or plugged back in. So the dual supplies really only provides redundancy for the switch itself (the switch will stay running even if either fails), but any devices that use the voltage that that power supply generated will be offline.