Serial Communication

• It is a method of conveying a single bit at a time i.e. only one bit of a word is transmitted at a time.
• It is slower.
• Hardware requirement is simple.
• E.g. RS-232C

Modes of serial data transfer

i) Simplex mode

• Data travel in only one direction. E.g. from computer to printer

ii) Half duplex mode

• Data travel in both directions but not at the same time.

iii) Full duplex mode

• Data travel in both directions at the same time.

Types of serial data transfer

i) Synchronous 

• Both transmitter and receiver are synchronized by same clock pulse.
• It is also called clock-oriented data transmission.
• Speed: >20 Kbps
• Always implemented with hardware.

ii) Asynchronous

• Both transmitter and receiver are synchronized by separate clock pulse.
• It is also called character-oriented data transmission.
• Speed: <20 Kbps.
• Always implemented with hardware and software.