Definition
Serial transmission is a method of transferring data one bit at a time over a single communication channel or wire. It is commonly used for communication between computers and peripheral devices such as printers and terminals, particularly for devices with relatively slow data transfer requirements.
Overview
In serial transmission, data bits are sent sequentially, each occupying a single time slot. This is in contrast to parallel transmission, where multiple bits are transferred simultaneously over multiple wires. Serial transmission is favored in long-distance communication and for connecting devices that do not require high-speed data transfers.
Types of Serial Transmission
Synchronous Serial Transmission
In synchronous serial transmission, data bits are sent in a continuous stream, synchronized by a common clock signal shared by the sender and receiver. This type is typically faster and more efficient but requires more complex hardware.
Asynchronous Serial Transmission
Asynchronous serial transmission sends data bits with start and stop bits, allowing the sender and receiver to operate independently without a synchronized clock. It is more flexible and easier to implement but generally slower due to the additional control bits.
Special Considerations
Transmission Speed
Serial transmission is suitable for varying speed requirements, from low-speed connections like RS-232 to high-speed requirements such as USB and Ethernet.
Distance and Interference
Serial transmission is more reliable over long distances compared to parallel transmission, which is susceptible to electromagnetic interference and signal degradation over longer cable runs.
Examples
Computer Terminals to Mainframes
Serial transmission was historically used to link computer terminals to mainframe computers, enabling data input and output over telephone lines or serial cables.
Microcomputers to Printers
In the context of microcomputers and printers, serial ports, often using standards like RS-232, provide a straightforward method for sending print jobs to printers, particularly in scenarios where high speed isn’t crucial.
Modern Applications
Modern serial transmission examples include USB (Universal Serial Bus), which connects a variety of peripherals to computers, and RS-485, commonly used in industrial and automation systems.
Historical Context
Evolution
Serial transmission has evolved from early telegraph systems to contemporary USB technology. The development of integrated circuits and advances in clock synchronization have significantly improved the efficiency and speed of serial communication.
Applicability
Networking
Serial transmission forms the backbone of many networking technologies. For instance, Ethernet originally used serial transmission techniques before evolving into more complex protocols.
Embedded Systems
Embedded systems frequently rely on serial communication (e.g., SPI, I2C) due to its simplicity and efficiency.
Comparisons
Serial vs. Parallel Transmission
While a serial transmission uses fewer wires and is more cost-effective and reliable over long distances, parallel transmission can achieve higher speeds over short distances but is more expensive and prone to interference.
Related Terms
- Baud Rate: The number of signal changes per second in a communication channel. In serial transmission, it often equates directly to bits per second.
- RS-232: A standard protocol for serial communication, widely used for connecting computers and peripherals.
- UART: Universal Asynchronous Receiver/Transmitter, a hardware component that handles asynchronous serial communication.
FAQs
What are the advantages of serial transmission?
How does serial transmission differ from parallel transmission?
What are some common uses of serial transmission today?
References
- Stallings, William. “Data and Computer Communications.” Pearson.
- Tanenbaum, Andrew S. “Computer Networks.” Prentice Hall.
- Behrouz A. Forouzan. “Data Communications and Networking.” McGraw-Hill.
Summary
Serial transmission, with its method of sending data one bit at a time over a single wire, remains a fundamental technique in the realm of data communication. Its various types, historical significance, and modern applications underscore its lasting relevance and versatility in an ever-evolving technological landscape. Understanding the nuances of serial transmission is essential for IT professionals and enthusiasts alike.
