A duplex outlet is 115vac.
Yes, the feeder will have to be a three wire cable.
Two-du plex
Seeing that the question comes from North America the most common duplex receptacle has 110 - 120 volts potential to ground. The second most common potential difference is 220 - 240 volts. These voltages are obtained from a 120/240 volt system common to home connections from the local utility companies.
CAN is half-duplex. One differential pair means one message at a time.
duplex duplex
There are many companies that sell Duplex printers. Duplex printers are able to print on both sides of a piece of paper. Online purchasing options include companies like HP and Amazon. Retail stores such as Walmart will also carry a variety of Duplex capable printers.
Many do, some don't.
45 volts
TCP is usually used as full duplex, but in some case, half duplex can also be used in TCP.
Full Duplex
1000
230 Volts