A data communication system has 5 necessary components which are listed as below.
The message is the information (data) to be communicated. Popular forms of information include text, numbers, pictures, audio, and video.
The sender is the device that sends the data message. It can be a computer, workstation, telephone handset, video camera, and so on.
The receiver is the device that receives the message. It can be a computer, workstation, telephone handset, television, and so on.
- Transmission Medium
The transmission medium is the physical path by which a message travels from sender to receiver. Some examples of transmission media include twisted-pair wire, coaxial cable, fiberoptic cable, and radio waves.
A protocol is a set of rules that governs data communications. It represents an agreement between the communicating devices. Without a protocol, two devices may be connected but not communicating.
Data Flow Directions
The direction of flow are of 3 types
- Unidirectional, One-way
- A sender can only send but not receive, and a receiver can only receive but not send
- Radio, Television broadcast are of simplex type
- Uses the entire capacity of the channel to send the data in one direction
- Bi-directional, 2-way communication
- When one is sending, other can only receive or vice-versa
- Full capacity of channel is taken over by whichever of the xdevice is transm
- Bi-directional, 2 way communication
- Able to send and receive data simultaneously
- Signals going in one direction share the capacity of the link with the signals going in the other directions
- Sharing can occur in 2 ways
- Either the link must have 2 physically separate transmission paths
- Or the capacity of the channel is divided between the signals traveling in both directions
- Common example: Telephone Network