Data communication involves the transfer of digital information between different points using various transmission modes and network configurations. Key aspects of data communication include serial and parallel transmission, simplex, half-duplex, and full-duplex transmission modes, and point-to-point and multipoint network configurations. Standards organizations like ISO, ITU-T, ANSI, IEEE, and EIA establish standards and recommendations for data communication systems and technologies.

1. Introduction to
Data
Communication

2. Introduction
•Data communications is the transfer of information from one point to
another. ‘Data’ refers to information that is represented by a sequence
of zeros and ones; the same sort of data that is handled by computers.
Many communications systems handle analog data; examples are the
telephone system, radio, and television. Modern instrumentation is
almost wholly concerned with the transfer of digital data.
•Any communications system requires a transmitter to send
information, a receiver to accept it and a link between the two. Types
of links include copper wire, optical fiber, radio, and microwave. Some
short distance links use parallel connections; meaning that several
wires are required to carry a signal.

3. Data Communications
• It is much like a regular communication among people , which
consists of the following parts;
• MESSAGE
• SENDER
• MEDIUM
• RECEIVER
https://www.youtube.com/watch?v=cxNxzJsyOfI&t=32s
https://www.youtube.com/watch?v=BnWn18qUYyA

4. Data
• information that has been processed and organized, it can be
alphabetical, numeric, or symbolic information, including
binary-coded alphanumeric symbols, microprocessor
op-codes, control codes, user addresses, program data, or
database information.

5. Brief History of Data
Communications
• Telegraph was invented and Samuel F.B. Morse developed Morse
code in 1837
• Emile Baudot invented a telegraph multiplexer, which allowed
signals from up to six different telegraph equipments in 1874
• Telephone was invented by Alexander Graham Bell in 1876

6. Standards Organizations
• International Standards Organization (ISO)
• Consultative Committee for International Telephony and
Telegraphy (CCITT)
• American National Standards Intitute (ANSI)
• Institute of Electrical and Electronics Engineers (IEEE)
• Electronics Industries Association (EIA)

7. ISO
(International Standards
Organization)
• the international organization for standardization
• creates the sets of rules and standards for graphics,
document exchange, and related technologies
• responsible for endorsing and coordinating the work of
the other standards organizations

8. ITU-T (CCITT) Consultative
Committee for International
Telephony and Telegraphy
• the standards organization for the United Nations and develops
the recommended sets of rules and standards for telephone
and telegraph communications
• developed three sets of specifications: the V series for modem
interfacing, the X series for data communications, and the I and
Q series for Integrated Services Digital Network (ISDN)

9. ANSI (American National
Standards Institute )
•official standards agency for the United
States
•US voting representative for ISO

10. IEEE (Institute of
Electrical and Electronics
Engineers )
• US professional organization of electronics, computer,
and communications engineers

11. EIA (Electronics
Industries
Association )
• Developed the RS (recommended Standard) series of
standards for data and telecommunications

12. Examples of DTE's are computers, printers, application servers,
file servers, routers and bridges, dumb terminals...etc. DTE do
not generally communicate with each other.
Data Terminal Equipment (DTE)
• A general term that describes the interface equipment used at
the stations to adapt the digital signals from the computers and
terminals to a form more suitable for transmission
• Any piece of equipment between the mainframe computer and
the modem or the station equipment and its modem

13. Data Communications
Equipment (DCE)
• A general term that describes the equipment that converts digital signals to
analog signals and interfaces the DTE to the analog transmission medium
• It is essentially a modem (modulator/demodulator)
https://www.youtube.com/watch?v=M4Nf2-g4LzE

14. The data transmission modes can be characterized in
the following two types based on the number of bits
sent simultaneously in the network:
1.Serial Data Transmission
2. Parallel Data Transmission
https://www.youtube.com/watch?v=ibiBj0irCtI

15. Serial Data
Transmission
• There is a single transmission line used
• Only one bit is transmitted at one time
• It is often called serial-by-bit transmission
• Used for long distance communications
This type of transmission mode is best suited
for long-distance data transfer, or the amount of
data being sent is relatively small.
For Example, Data transmission between two
computers using serial ports.

16. Following are the advantages of using a serial transmission mode:
1.It can be used for long-distance data transmission as it is
reliable.
2.The number of wires and complexity is less.
3.It is cost-effective.
Following are the disadvantages of using a serial transmission mode:
1.The Data transmission rate is slow due to a single transmission
channel.

17. Parallel Data
Transmission
To transfer data on a parallel link, a
separate line is used as a clock signal.
This serves to inform the receiver when
data is available.
In addition, another line may be used
by the receiver to inform the sender
that the data has been used, and its
ready for the next data.
For Example, Data transmission between computer and
printer.

18. Following are the advantages of using a parallel transmission mode:
1.It is easy to program or implement.
2.Data transmission speed is high due to the n-transmission channel.
Following are the disadvantages of using a parallel transmission mode:
1.It requires more transmission channels, and hence cost-ineffective.
2.Interference in data bits, likewise in video conferencing.

19. https://www.youtube.com/watch?v=g1Qyzi6vs8g

20. Data Communications Circuit
Configurations
• Two-point configuration involves only
two locations or stations; e.g. the
transfer of information between a
mainframe computer and a remote
computer terminal, two mainframe
computers, or two remote computer
terminals
• Multipoint configuration
involves three or more stations or
terminals; e.g. the interconnection
of a single mainframe computer to
many remote computer terminals

21. The data transmission modes can be characterized in the following three types based on the
direction of exchange of information:
1.Simplex
2. Half-Duplex
3. Full Duplex

22. Transmission
Modes
• Simplex (SX)
Simplex is when signals travel
in one direction and one
direction only.
It is like a one way street. It is
simple . That is why it is called
simplex
Examples of a simplex transmission
is everywhere in our daily life:
In this devices the communication
is only one direction
A radio or TV station usually sends
signals to the audience but never
receives signals from them,thus a radio
or TV signal transmission is considered
a simplex.

23. Following are the advantages of using a Simplex transmission mode:
1.It utilizes the full capacity of the communication channel during data
transmission.
2.It has the least or no data traffic issues as data flows only in one direction.
Following are the disadvantages of using a Simplex transmission mode:
1.It is unidirectional in nature having no inter-communication between
devices.
2.There is no mechanism for information to be transmitted back to the
sender(No mechanism for acknowledgement).

24. • Half-Duplex (HDX)
Half duplex transmission is when signals travel in both directions , but
one at a time.
One example is a walkie talkie.
Both transmitter and reciver can send signals , but they must take turns.
Transmission Modes

25. Following are the advantages of using a half-duplex transmission mode:
1.It facilitates the optimum use of the communication channel.
2.It provides two-way communication.
Following are the disadvantages of using a half-duplex transmission mode:
1.The two-way communication can not be established simultaneously at
the same time.
2.Delay in transmission may occur as only one way communication can be
possible at a time.

26. • Full-Duplex (FDX)
Full duplex is a two way communications and signals travel
in both directions simultaneously
Telephone call is an example.
Transmission
Modes

27. Following are the advantages of using a full-duplex transmission mode:
1.The two-way communication can be carried out simultaneously in
both directions.
2.It is the fastest mode of communication between devices.
Following are the disadvantages of using a half-duplex transmission mode:
1.The capacity of the communication channel is divided into two parts.
Also, no dedicated path exists for data transfer.
2.It has improper channel bandwidth utilization as there exist two
separate paths for two communicating devices.