What is a serial port?
Sewell InstaCOM USB to Serial Adapter 2 ft, with Posts,
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The Serial Port is a data communication port that has been widely replaced by USB at this point. Serial is still used in legacy applications, mostly with industrial equipment. Serial communication means that it sends one bit at a time. Many popular data connections use the serial communication method. The term Serial Port, however, most commonly refers to a port that communicates using the RS-232 standard.
Some of the most common uses for the serial port have been to connect external data/fax modems, old mice, label printers, PDAs, and various manufacturing and testing equipment. Lots of A/V equipment including audio receivers, cable boxes, DVRs, TVs, etc, include an RS-232 serial port on them which can be used to update or reconfigure the equipment if needed.
There are a few different standards that are commonly used with a serial port.
- RS-232 - The most common serial communication standard for Serial Ports
- RS-422 - A high-speed system similar to RS-232 but with differential signaling
- RS-423 - A high-speed system similar to RS-422 but with unbalanced signaling
Running serial a long distance can cause problems with degradation in the signal quality. To resolve this issue you can use serial extenders which will run the signal over CAT5 cable and allow you to make much longer runs.
Another common issue people run into is the fact that newer computers do not generally have serial ports on them. If your computer does not have serial, but you need to communicate with a serial device you can use a USB to Serial adapter to add a serial port to that computer. This will allow you to communicate with serial equipment as if you had a true serial port on the computer.
There are several physical ports that have been used for serial communication. Here are a few of the most common:
- DB-25 - The original port used for the RS-232 Serial Port
- DE-9 - This port is commonly mislabeled as a DB-9 port and is the most commonly used port
- Mini Din-8 - This port was used primarily by the companies Apple and SGI as a serial port on their systems
See more data connection types