Hardware Handshaking


Hardware handshaking is a method of communication between devices, where physical or electronic signals are used to coordinate the transfer of data. This method ensures that both devices are ready to send and receive data before the actual transfer occurs. Also known as flow control, hardware handshaking helps prevent data loss or corruption by managing the pace at which data is exchanged.


The phonetic spelling of “Hardware Handshaking” using the International Phonetic Alphabet (IPA) is:/ˈhɑrdˌwɛr ˈhændˌʃeɪkɪŋ/Breaking it down:Hardware – /ˈhɑrdˌwɛr/Handshaking – /ˈhændˌʃeɪkɪŋ/

Key Takeaways

  1. Hardware handshaking is a communication mechanism that uses control signals to synchronize data transmission between devices, ensuring that there are no data collisions or lost data.
  2. It typically uses signal lines for Request to Send (RTS) and Clear to Send (CTS), which indicate when a device is ready to start sending or receiving data, preventing buffer overflow.
  3. Hardware handshaking increases the efficiency and reliability of data transfer and is commonly used in serial communications, including the RS-232 standard.


Hardware handshaking is an important technology term because it refers to the process of establishing and maintaining a reliable communication link between two hardware devices, ensuring that data is transmitted and received with minimal errors.

This is crucial in various computing systems, as it enables devices to synchronize their data transfer rates, prevent data loss or corruption, and manage resource allocation efficiently.

By employing hardware handshaking methods, such as the commonly used UART/USART-based protocol, computers, and peripherals can communicate effectively, enhancing the overall performance of the system and providing the foundation for a wide array of applications, including industrial automation, telecommunications, and smart devices, among others.


Hardware handshaking serves as a method of communication between two devices in a computer system, ensuring that data transfer occurs efficiently, accurately, and securely. This process allows these devices to coordinate and manage the flow of information by employing a set of specific signaling lines or control signals that are part of the communication interface. By using these signaling lines, the receiving device sends an acknowledgment signal back to the sending device, granting permission to send more data or indicating that the receiving device is currently unable to accept any more information.

Consequently, hardware handshaking supports the establishment of a harmonious data exchange and maintains an effective transfer rate by preventing the loss or corruption of important information during transmission. The primary purpose of hardware handshaking is the regulation of data flow, which is particularly crucial when the sender and receiver are operating at different speeds or with varied processing capabilities. This synchronization ensures that both devices share a common understanding of each other’s limitations and readiness for data transfer.

A practical example of hardware handshaking in action is the communication between a computer and a printer, where the printer might take longer to print a document than the computer requires to send the data. Through hardware handshaking, the printer alerts the computer about its readiness, thus preventing the computer from sending too much information and overwhelming the printer’s buffer capacity. In this way, hardware handshaking facilitates smooth and reliable device communication, enabling systems to function seamlessly in various technological applications.

Examples of Hardware Handshaking

Hardware handshaking is a process used in communication systems to establish and maintain a smooth data exchange between devices. Here are three real-world examples of hardware handshaking:

UART Communication: Universal Asynchronous Receiver/Transmitter (UART) is commonly used for serial communication between two devices. A common application is for Microcontroller-PC communication. Hardware handshaking in UART, also known as “flow control,” uses two dedicated pins—Clear To Send (CTS) and Ready To Send (RTS). The transmitting device asserts the RTS signal to indicate it is ready to send data, and the receiving device sends a CTS signal to acknowledge it is ready to receive the data. This handshake helps prevent data loss or buffer overflow by ensuring both devices are prepared to exchange data.

IEEE-1284 Parallel Port: The IEEE-1284 parallel port, also known as the Centronics port, was widely used for connecting printers and other devices to PCs in the 1990s. The 36-pin interface supports hardware handshaking using dedicated pins for strobe, acknowledge, busy, and other signals. This ensures smooth communication between the computer and peripheral devices—such as printers—preventing data corruption and ensuring accurate printing results..

RS-232 Serial Communication: The RS-232 standard is commonly used for serial communication between devices, particularly in industrial environments. The standard supports hardware handshaking using dedicated pins for CTS (Clear To Send) and RTS (Request To Send) signals, along with Data Terminal Ready (DTR) and Data Set Ready (DSR) signals. When using hardware handshaking in RS-232 communication, these signals synchronize the data transmission and establish error-free data exchange between devices, such as data loggers, industrial controllers, and programmable logic controllers (PLCs).

Hardware Handshaking FAQ

What is hardware handshaking?

Hardware handshaking is a communication mechanism between two devices that uses hardware signals to synchronize and regulate the transmission of data. It ensures that both devices are ready to send and receive data before proceeding with the communication process.

How does hardware handshaking work?

Hardware handshaking uses dedicated handshaking lines in addition to the data lines. The most common example is the RTS (Request to Send) and CTS (Clear to Send) signals in the RS-232 standard. The transmitting device sets the RTS signal to indicate it is ready to send data, and the receiving device sets the CTS signal when it is ready to receive data. Data transfer occurs only when both signals are active.

What are the advantages of hardware handshaking?

Hardware handshaking provides a reliable and efficient method of managing data transmission by ensuring that devices are ready to communicate before data transfer occurs. This prevents data loss or corruption due to overloading or buffer overflow in the receiving device. It also allows for flow control, enabling better communication between devices with varying data processing speeds.

What is the difference between hardware handshaking and software handshaking?

Hardware handshaking uses dedicated hardware signals to manage data transmission, whereas software handshaking relies on specific data characters or codes embedded within the transmitted data stream. Software handshaking is also known as XON/XOFF handshaking and uses the XON and XOFF characters to control the flow of data between devices.

Where is hardware handshaking typically used?

Hardware handshaking is commonly used in various communication interfaces and protocols, such as RS-232, RS-485, and parallel port communications. It is also used in modems, printers, and other peripheral devices to ensure reliable data transmission and prevent data loss or corruption.

Related Technology Terms

  • Serial Communication
  • Flow Control
  • Request to Send (RTS)
  • Clear to Send (CTS)
  • Data Terminal Ready (DTR)

Sources for More Information


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