Datalink

In telecommunication a data link is the means of connecting one location to another for the purpose of transmitting and receiving digital information. It can also refer to a set of electronics assemblies, consisting of a transmitter and a receiver (two pieces of data terminal equipment) and the interconnecting data telecommunication circuit. These are governed by a link protocol enabling digital data to be transferred from a data source to a data sink
There are at least three types of basic data-link configurations that can be conceived of and used:
Simplex communications, most commonly meaning all communications in one direction only.
Half-duplex communications, meaning communications in both directions, but not both ways simultaneously.
Duplex communications, communications in both directions simultaneously. For more information http://www.datalinkindia.com/