Serial Communication Basics

Serial connectors are generally found on older computers known as legacy systems.

Serial ports are full-duplex communication channels that send and receive data synchronously between your system and other attached devices. This means your serial port simultaneously receives data from the connected device while it sends out packets of information.

Function

Serial ports are device communication channels found mostly on older computers. Serial communication is not only used for computing, but is also a common communication protocol for various instruments and devices that come with an EIA-232 port. EIA-232 ports are also referred to as RS-232.

Developer

The Electronics Industries Association (EIA), along with other interested parties, developed the RS-232 standard communication protocol. The main purpose of RS-232 is to distinctly identify the serial interface between Data Communication Equipment (DCE) and Data Terminal Equipment (DTE).

Connection Types

There are three types of RS-232 (serial) connectors: DB9 male, DB9 female and DB-25 male/female plug. The DB9 male socket is used on DTE (data terminal equipment), such as a computer. The DB9 female plug is utilized on DCE (data communication equipment), such as a modem. The DB-25 is somewhat unique in that it serves as a serial connector to your computer while it also provides a parallel interface for your printer.

References

• National Instruments: Serial Communication Overview
• Connexions: Serial Port Communication
• Siong Boon: Serial Communication
• Null Modem: DB-25 Connector

Resources

• TALTech: Introduction to Serial Communications