what is duples and simples in communication?

Simplex communication is a communication channel that sends information in one direction only.
A "duplex" communication channel requires two simplex channels operating in opposite directions.
For example, in TV and radio broadcasting, information flows only from the transmitter site to multiple receivers. An RS 232 interface between a computer terminal and a modem is made up of multiple simplex control and data circuits, but information can flow both ways since channels are provided both to and from the terminal.

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