bidirectional (BiDi)

Bidirectional is an operating mode of data communication. In bidirectional operation, two signals can be transmitted simultaneously in both directions over one transmission line.

There are two channels between the transmitter and receiver: an outward and a return channel. Each participant in a bidirectional connection can thus be either a transmitter or a receiver. In bidirectional operation, a distinction is made between those in which only one station can transmit and the other receive, i.e. half- duplex operation, and those in which both stations can transmit and receive simultaneously, i.e. duplex or full-duplex operation.

The opposite of bidirectional operation is unidirectional operation, also known as simplex operation.