A Comparison of Parallel Data Transmission and Serial Data Transmission

The data between two computers is exchanged in either of the two transmission modes – serial or parallel. Although most of us use computers, laptops, and several network devices,we are largely unaware of these data transmission types. These types are similar and dissimilar in many ways. This post introduces you to these types and also compares them to help you understand their differences.

Parallal data transmission Vs. Serial Data Transmission

Basic Definitions of Serial and Parallel Transmission

The following pointers will help you understand the differences between serial and parallel transmission.
  • Serial Transmission: In this type of transmission a single link is used to transmit data bits and only one bit is transferred at a time.
  • Parallel Transmission: In this transmission, data bits are transmitted simultaneously through multiple links, which are placed parallel to each other. Contrary to serial transmission where only one bit is transmitted at a time, eight bits of data can be transmitted simultaneously in parallel transmission.

Parallel vs. Serial Transmission: A Few Important Factors Compared

Is parallel communication effective or serial communication? The following pointers will help you make the decision.
  • Speed: As said before, the parallel communication channel may comprise multiple electrical conductors at the physical layer to send eight bits or bytes. When compared with serial transmission at the same speed, the parallel transmission will be eight times faster.
  • Disturbances: In serial transmission, multiple bits are simultaneously sent in one clock pulse, which produces noise and leaves scope for error. However, in serial transmission one bit is sent at a time, so there is no crowding and hence minimal chances of error and noise. This means electromagnetic interference is negligible or zero in case of serial transmission.
  • Transmission Distance: Parallel communication may witness electromagnetic interference in long distance transmission, which is why they are used in short distance transmission. Against this, serial transmission is ideal for long distance data transmission. Most computer networks use serial communication.
  • Converters: Serial transmission utilizes converters that enable data conversion from parallel to serial type, while parallel transmission requires no such data converters
  • Transmission Modes: In parallel data communication, although eight bits can be sent at a time, it has a half-duplex transmission mode. This is because the data can be either sent or received at a time. However, in serial transmission, the sender can receive and send the data simultaneously. Thus, it has a full-duplex transmission mode.
  • Affordability: Parallel communication has been used for integrated circuits as well as RAM and peripheral buses. However, serial communication is used in computer networks. By closely observing these examples, the integrity and complexity of different applications can be easily made out. On comparison, it can be rightly said that serial communication is cheaper compared to parallel communication.
  • Complexity of Connections: A parallel connection may require several devices and cables, which adds to its complexity. Against this, a serial connection requires fewer cables for interconnection, and requires less space, too. Its small footprint enables better isolation of the system from its surroundings.
  • Clock Skew: This is also known as timing skew, and it is a phenomenon in computers and other digital circuit systems where the same clock signal will report to different components with certain time differences. The difference between the clock readings is known as a skew. In parallel communication, the clock skew between different channels can be an issue, while in serial communication, this is not an issue.
  • Cable Lengths: The serial communication cables are longer, thinner, and economical when compared to parallel communication cables, and they run to several kilometers.
Knowing the similarities and differences between serial communication and parallel communication may not serve the purpose. You must use quality devices that enable conversion from serial-to-parallel or vice versa. VERSITRON provides serial to fiber converters, which serve as converters for serial RS-422, RS-232, RS-449, RS-485, and V.35 protocols. These modems can support a multidrop, a redundant ring, and a point-to-point link.

Rich Tull

R.W. Tull is the President of Versitron Inc. He works closely with clients to review layout diagrams and drawings in order to ensure that the best fiber optic solution is achieved for a particular project.

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