Definition of DB-9

DB-9 refers to a type of connector commonly used in computer systems and electronic devices. It is a 9-pin, D-shaped connector, also known as a D-subminiature or D-sub, used for various types of data communication, such as serial port connections. These connectors are often found on older computers and peripherals, but have been largely replaced by newer connection standards.


D as in Delta, B as in Bravo, – (hyphen), 9 as in Nine

Key Takeaways

  1. DB-9 is a 9-pin connector commonly used for serial communication in computing devices and peripherals
  2. It is frequently used for RS-232 serial connections, allowing data transfer between devices such as computers, modems, and other peripherals
  3. DB-9 connectors have been largely replaced by USB and other more advanced connection types in modern devices, but they still remain in use for legacy systems and some industrial applications

Importance of DB-9

The term DB-9 refers to a type of connector commonly used in electronics and computer hardware for various applications, including serial communication.

It is important because it has been widely adopted and serves as the standard for connecting devices like computers, peripherals, and other equipment.

DB-9 connectors enable efficient data transfer and secure connections in a compact form factor, allowing easy integration into different systems.

They have played a critical role in the development of the technology industry, providing reliable connections in numerous applications such as personal computers, industrial machinery, and communication devices.


The DB-9 connector, also referred to as a DE-9 connector, is a widely-used type of connector designed to facilitate reliable and convenient data communication between various electronic devices and systems. Primarily utilized in serial communication, DB stands for “Data Bus” and the number 9 refers to the number of pins in the connector.

DB-9 connectors were commonly used in personal computers as serial ports, forming an interface to connect peripheral devices such as modems, mice, or other data equipment. They have served a pivotal role in ensuring synchronized and effective data transmission, fostering a seamless exchange of information across an array of electronic devices.

Despite the emergence of advanced connector technologies, such as USB and HDMI, the DB-9 connector is revered for its dependability and remains in use across numerous applications today. For instance, DB-9 connectors are still employed in the realm of industrial automation, where they may interface with programmable logic controllers, barcode scanners, or other critical equipment.

Moreover, in the telecommunications arena, the connector is often used on console ports of network equipment like routers and switches. The versatility and simplicity of the DB-9 connector, combined with its ability to maintain effective communication, make it a resilient technology that continues to thrive in the ever-changing landscape of data transmission.

Examples of DB-9

DB-9, also known as DE-9 or RS-232, is a type of connector commonly used for data transfer and serial communication. Here are three real-world examples of DB-9 technology in use:

Device-to-Device Communication: Many industrial and lab equipment use DB-9 connectors to facilitate communication between different devices. For example, older PLCs (Programmable Logic Controllers) used DB-9 connectors to establish communication with control panels or other machinery for data exchange and synchronization.

Networking Equipment: Some early network devices, such as Ethernet or token ring network adapters in older computer systems, used DB-9 connectors to establish a wired connection. Routers, switches, and hubs also incorporated DB-9 connectors for configuration and management purposes, allowing administrators to connect to the equipment using a serial cable.

Personal Computer Peripherals: In the past, DB-9 connectors were commonly used to connect computer peripherals such as mice, modems, and joysticks. Mice with DB-9 connectors were typically seen in IBM PC-compatible systems, while the modems allowed for dial-up internet connectivity. Similarly, joysticks using DB-9 connectors facilitated gaming and other interactive applications on home computers.


What is a DB-9 connector?

A DB-9 connector is a 9-pin D-sub miniature connector used for various computer and communication purposes. It is commonly used for serial communication between devices such as computers, modems, and other peripherals.

What are some common uses of DB-9 connectors?

DB-9 connectors are typically used for serial communication, particularly RS-232 applications, which include connecting devices like computers, modems, printers, and other peripherals. They can also be utilized in video game controllers, instrumentation, and industrial machinery.

How do I identify a DB-9 connector?

A DB-9 connector can be identified by its unique D-shaped profile and its arrangement of 9 pins, separated into two rows of 5 and 4 pins. It is typically smaller than the 25-pin DB-25 connector commonly used for parallel communication.

Is a DB-9 connector the same as RS-232?

No, a DB-9 connector is not the same as RS-232. The DB-9 connector is a type of hardware connector, whereas RS-232 is a standard for serial communication. A DB-9 connector can be used for RS-232 communication, but not all RS-232 connections utilize the DB-9 connector.

Are there different types of DB-9 connectors?

Yes, there are different types of DB-9 connectors. The most common types are male and female DB-9 connectors, with male connectors having protruding pins and female connectors featuring corresponding sockets. Additionally, there are right-angle DB-9 connectors and DB-9 connectors with integrated strain relief for more specialized applications.

How do I wire a DB-9 connector for serial communication?

When wiring a DB-9 connector for serial communication, it is essential to follow the specific pin assignments for your application. For RS-232 communication, pin assignments typically include TxD (Transmit Data) on pin 3, RxD (Receive Data) on pin 2, and GND (Ground) on pin 5. Always refer to the documentation for your specific devices and connection standards to ensure correct wiring.

Related Technology Terms

  • Serial Communication
  • RS-232 Interface
  • D-subminiature Connectors
  • 9-pin Connector
  • COM Port

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