What are Synchronous Protocols?

Synchronous protocols take the whole bitstream and drop it into the character of equal size. It is a data transfer approach in which it is a continual flow of information signals followed by computing signal.

These protocols facilitate the provision that the broadcaster and the receiver are integrated. This transmission approach is mainly used when vast amounts of record are needed to be moved from one area to another.

There are two types of synchronous protocol which are as follows −

Character Oriented Protocols

It is also called as the byte-oriented protocol to interpret a transition frame or packet as a character succession.

Binary Synchronous Communication (BSC)

It is a famous oriented data link protocol produced by computer hardware company IBM. It has specified half-duplex transmission with a stop-wait argument.

There are two types of BSC Frames as given below −

  • Control Frame

  • Data Frame

BISYNC or BSC was one of the most widely used protocols (data link control method) worldwide. It is applicable for half-duplex, point to point or point to multipoint lines. It is a Character Oriented protocol and uses the American Standard Code for Information Interchange (ASCII), Extended Binary Coded Decimal Interchange Code (EBCDIC), or Transcode.

The frame format is shown in the figure below −

Error Check Field
BSC Frame Format

Bit-Oriented Protocols

It can pack more information into the shorter frame and avoid the transparency problem of the character-oriented protocol. This frame or packet is interpreted as a series of bits. For example, High-level Data Link Control (HDLC) and Software Development Life Cycle (SDLC).

Working of Synchronous Protocol

  • It can separate the clocking lines when the area between the data terminal equipment (DTE) and data communications equipment (DCE) is precise.

  • This approach uses a clocking electrical system at both sending and receiving locations. This provides that the transmission procedure is synchronized.

  • It is a device that connects by using either separate clocking channels.


The advantages of Synchronous Protocol are as follows −

  • It helps us to transfer a huge amount of data.

  • It offers real-time transmission between linked machines.

  • Each byte is sent without an inconsistency between the next byte.

  • It is used to decrease the timing errors.


The disadvantages of Synchronous Protocol are as follows −

  • The efficiency of the received information relies on the receiver's capability to calculate the received bits correctly.

  • The sender and receiver are required to work together with an equal clock frequency.