In Computers, communication ports can be divided into two types based on the type or protocol used for communication. They are Serial Ports and Parallel Ports. A serial port is an interface through which peripherals can be connected using a serial protocol which involves the transmission of data one bit at a time over a single communication line.
The most common type of serial port is a D-Subminiature or a D-sub connector that carry RS signals. A parallel port, on the other hand, is an interface through which the communication between a computer and its peripheral device is in a parallel manner i.
Printer port is an example of parallel port. The article gives a brief introduction to different types of ports along with their applications. There are two types of serial ports that are commonly found on a computer: DB and DE DB is a variant of D-sub connector and is the original port for RS serial communication. They were developed as the main port for serial connections using RS protocol but most of the applications did not require all the pins.
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.
Originally, the primary use of a serial port was to connect a modem to your computer. The pin assignments reflect that. Let's take a closer look at what happens at each pin when a modem is connected. Voltage sent over the pins can be in one of two states, On or Off.
An important aspect of serial communications is the concept of flow control. This is the ability of one device to tell another device to stop sending data for a while. Let's look at an example of how flow control works: You have a modem that communicates at 56 Kbps. The serial connection between your computer and your modem transmits at Kbps, which is over twice as fast.
This means that the modem is getting more data coming from the computer than it can transmit over the phone line. Even if the modem has a K buffer to store data in, it will still quickly run out of buffer space and be unable to function properly with all that data streaming in. With flow control, the modem can stop the flow of data from the computer before it overruns the modem's buffer.
The computer is constantly sending a signal on the Request to Send pin, and checking for a signal on the Clear to Send pin. If there is no Clear to Send response, the computer stops sending data, waiting for the Clear to Send before it resumes. This allows the modem to keep the flow of data running smoothly.
Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Computer Hardware. How Serial Ports Work. This is more a theoretical concept.
There are also cables with a handshaking simulation on a «stub» and partial handshaking without the ability to control the data transmission at the «hardware level». The following is the RS cable wiring with full handshaking recommended by Microsoft. At one point, the RS 9-pin Serial Port used to be a common connector on the back of every computer.
But with USB being a much better protocol and easier to use, the serial port has just about disappeared from modern desktop computers.
If you want to know more about how I discovered this and the differences, then continue reading. When using the Keyspan adapter, the only caveat is that communication with the UPS is configured as using a serial cable instead of a USB cable. This caused a bit of a problem for me. For a typical USB configuration, apcupsd. This is because apcupsd will try all the known USB ports until it succeeds. However, when using the Keyspan USB-to-serial adapter, apcupsd. The next time the server rebooted, it could have been ttyUSB1.
This was unreliable, so I wanted to figure out what the problem was with my serial connection. After a bit of research, I learned that there were two pinout conventions used for the IDC10 header on motherboards. Once I discovered that there were two industry standard conventions in use for the IDC COM header connector pinout, my problem was solved.
A quick fix was to buy the correct adapter.
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