What is Simplex, Semi-Duplex and Full-Duplex?

In telecommunication, a duplex connection is a connection with which can be communicated simultaneously in two directions. This is also known as full-duplex. That is to be able to distinguish it from the semi-duplex. Semi-duplex is a two-way connection with which communication cannot take place simultaneously in two directions. Communication takes place from the one side or the other. A connection that only goes in one direction is called a simplex-connection.

Simplex communication connection

A radio remote control with a simplex-connection can only send signals to the receiver. This is the easiest communication link. For example, a remote control can transmit a command for a pump to start up. However, this will not receive a return signal and in this case it knows that the pump is actually on.

Semi-duplex communication connection

A radio remote control with a semi-duplex connection can send and receive signals to or from the radiographic receiver. However, at the moment that the signals are sent the remote control cannot receive any return signals from the receiver. As soon as the signal is sent, the “ears” of the remote control are open and listening for incoming signals from the specific receiver. With semi-duplex these signals are a “yes” or “no” which can be translated in a led light that goes on or off.

Full-duplex communication connection

The most advanced connection link is the full-duplex connection. Here the remote control can receive signals and at the same time transmit signals. For remote controls with a full-duplex connection it is possible, by means of a display, to receive values of all types which can be a great help for the operator. For example, consider a hoist that can measure the weight of an object. The weight on the hoist can then immediately be sent back to the remote control.

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