Data communication involves the exchange of data between two devices via a transmission medium like wired cables or radio waves. A successful data communication system depends on accurate and timely delivery of data. There are five key components of a data communication system: the medium that transmits the data, protocols that establish communication rules, and the direction of data flow which can be unidirectional, one direction at a time, or both directions simultaneously.

2. Data Communications
Data communication is the exchange of data between two devices via
some form of transmission medium (wire cable).
face to face over distance

3. Effectiveness of data communication system depends on:
Data Communications

4. Data Communications
Delivery Accuracy
Timeliness

5. Data Communications

6. Components
A data communication system is made up of five
components

7. Medium: The physical path by which a message
travels from sender to receiver
– twisted pair, coaxial cable, fiber-optic, radio
waves
Components
Medium

8. Protocol: a set of rules that govern data communications
– An agreement between the communicating devices
– Devices may be connected but not communicating (no
protocol)
– Arabic speaker with Japanese speaker
Components
Protocol

9. Data Flow
Communication between two devices can be:
Full Duplex
Simplex
Half Duplex

10. Data Flow
Simplex
The communication is unidirectionalThe communication is unidirectional.
Only one device on a link can transmit; the other can only receive

11. Data Flow
Half-Duplex
Each station can both transmit and receive, but not at the same time

12. Data Flow
Full-Duplex
Both stations can transmit and receive at same time