The term full duplex describes simultaneous data transmission and receptions over one channel. A full duplex device is capable of bi-directional network data transmissions at the same time. Half duplex devices can only transmit in one direction at one time. With half duplex mode, data can move in two directions, but not at the same time. The term duplex, on its own, refers to the capability to send and receive data. Duplex is often used when talking about conversations over a telephone or computer. A full duplex Ethernet environment can use a pair of twisted cable for packet receiving and a pair of twisted cable for transmission.
Full/Half Duplex Devices
In data communications, the full/half-duplex device allows users to choose either full or half duplex modes. With half-or-full duplex devices, such as modems, a switch will be set to either full or half mode. The mode can be modified to correspond with each specific type of communication program. When set to a half duplex system, connections alternate use of the communication channel, and hardware can determine the time each data link in the system is allotted for transmissions.
Differences Between Full and Half Duplex Systems
There are distinct differences between full and half duplex systems. With half-duplex mode, each transmitted character is immediately displayed on a monitor. If a device is operating in full duplex mode, transmitted data does not appear on-screen until it is received and returned. Full-duplex Ethernet does save time when compared to half-duplex, because it alleviates collisions and frame retransmissions. Sending and receiving are separate functions, creating a system where there is full data capacity in each direction. In contrast, half-duplex can be used to conserve bandwidth.