Transmission Modes/Ways/Methods:

There are three transmission modes for transmitting data from one point to another these are:

a. Simplex

b. Half Duplex

c. full Duplex

If transmission is simplex; communication can take place only one direction. Devices connected to such a circuit are either send only or receive only devices.

For example, a data collection terminal on factory floor (send only) or a line printer (receive only). simplex circuits are seldom used because a return path is generally needed to send acknowledgment, control, or error signals.

A half duplex system can transmit data in both directions but only in one direction at a time. Thus a half duplex line can alternately send and receive data.

In half duplex system the line must be turned around each time the direction is reversed. this involves a special switching circuit and require a small amount of time. But some applications require a simultaneous transmission in both directions, In such cases a full duplex system is used that allows information to flow simultaneously in both directions on the transmission path. Use of full duplex improves the efficiency.

Sender and	Full Duplex ←	Receiver and
Receiver	And →	Sender

 

Transmission Modes
Channel Type	Directionality
Simplex	Data can be transmitted in one direction
Half Duplex	Data can be transmitted in both directions, but only one direction at a time
Full Duplex	Data can be transmitted in both directions simultaneously

 

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