What is a serial port for a computer

They are asynchronous interfaces that can transmit one bit of data at a time when connected to a serial device. In traditional personal computers, COM1 and COM2 were often used to connect a serial port device such as a modem or mouse. Serial devices are pieces of electronic equipment that are characterized by the way they transmit data.

Information is sent and received one bit at a time, which provides for a simple and reliable method of communication. Serial ports are not standard equipment on the majority of newly manufactured desktop and laptop computers. This does not mean that you cannot connect a serial port device to a new computer. You can use a USB to serial adapter which can provide single or multiple COM ports to machines that do not have any installed serial interfaces.

There are many solutions available, and most are inexpensive and easy to implement. The adapters work by installing a device driver on a Windows computer. The driver is a program that enables the computer to use the USB to RS adapter as a replacement for a serial interface. USB interfaces have largely replaced COM ports as a faster way of performing serial data transmission.

Most computers are equipped with internal modems, eliminating the need for external serial devices. Similarly, COM connected mice are no longer widely used to input data. Null-modem cables can be used with serial interfaces to connect two computers, but this method is rarely used anymore. Serial ports are still used in many specialized situations. Some examples are surveillance cameras and equipment used for industrial automation implementations.

They employ the RS interface which is still supported by the hardware on many modern computers. Since many cost-efficient serial over Ethernet software and hardware solutions enable COM ports to be used on machines that are not equipped with any, we can expect the RS protocol to be around for a while.

A COM port also has the advantage of being able to power 15 meters of shielded cable. A comparable USB cable would be limited to a length of 5 meters. Serial ports come in two standard configurations. They are usually male connectors with either 9 or 25 pins. Parallel ports that are used to connect a partner cable are 25 pin female connectors.

Each pin is used for a particular function such as sending and receiving data or sending a terminal ready message. Essentially, any interface that is compliant with the RS protocol is a serial port. The RS protocol is used by many device manufacturers. You will find serial connectivity built into devices like GPS receivers, industrial automation sensors, barcode scanners, and computer monitors, to name just a few. Hence, DE-9 was developed for RS based serial communication while DB was rarely used as a serial port and often used as a parallel printer port as a replacement of the Centronics Parallel 36 pin connector.

DE-9 is the main port for RS serial communication. It is a D-sub connector with E shell and is often miscalled as DB Some of the applications of DE-9 port are serial interface with mouse, keyboard, modem, uninterruptible power supplies UPS and other external RS compatible devices.

Parallel port is an interface between computer and peripheral devices like printers with parallel communication. The Centronics port is a 36 pin port that was developed as an interface for printers and scanners and hence a parallel port is also called as a Centronics port. Before the wide use of USB ports, parallel ports are very common in printers. The Centronics port was later replaced by DB port with parallel interface. Audio ports are used to connect speakers or other audio output devices with the computer.

The audio signals can be either analogue or digital and depending on that the port and its corresponding connector differ. It is the most commonly found audio port that can be used to connect stereo headphones or surround sound channels. A 6 connector system is included on majority of computers for audio out as well as a microphone connection. These 6 connectors can be used for a surround sound configuration of up to 8 channels. It is a D-sub connector consisting of 15 pins in 3 rows. The connector is called as DE VGA carries analogue video signals up to a resolution of X Some laptops are equipped with on-board VGA ports in order to connect to external monitors or projectors.

The pinout of a VGA port is shown below. DVI is a high speed digital interface between a display controller like a computer and a display device like a monitor. It was developed with an aim of transmitting lossless digital video signals and replace the analogue VGA technology.

The digital signals can be either single link or dual link where a single link supports a digital signal up to X resolution and a dual link supports a digital signal up to X resolution.

It is smaller than a regular DVI port. The following image shows a Mini-DVI port and its compatible cable. Display Port is a digital display interface with optional multiple channel audio and other forms of data. The Display Port has a 20 pin connector, which is a very less number when compared to DVI port and offers better resolution. The pin out diagram of a Display Port is shown below.

Update: DisplayPort 1. An improved DisplayPort version 2. Even though Mini DisplayPort has 20 pins, the physical size of the connector is smaller than a regular DisplayPort and the pin out is also different. RCA Connector can carry composite video and stereo audio signals over three cables.

Composite video transmits analogue video signals and the connector is as yellow colored RCA connector. The video signals are transmitted over a single channel along with the line and frame synchronization pulses at a maximum resolution of i standard resolution. The red and white connectors are used for stereo audio signals red for right channel and white for left channel. Component Video is an interface where the video signals are split into more than two channels and the quality of the video signal is better that Composite video.

Like composite video, component video transmits only video signals and two separate connectors must be used for stereo audio. Used commonly with older computers, however, is also commonly used for its ease of use. Network - One of the original uses of the serial port, which allowed two computers to connect together and allow large files to be transferred between the two. Printer - Today, this not a commonly used device for serial ports. However, was frequently used with older printers and plotters.

Below is a listing of each of the pins on the DB9 connector, their purpose, and signal name. With many computers, the serial port is labeled as " " which are ones and zeros to represent binary. As shown above, pin one is in the top-left portion of the port and pin 9 is in the bottom right.

Most of today's computers are eliminating the serial port in favor of USB ports. Where is the serial port on a computer?