Editing RS-232 (section)

==Role in modern personal computers==
{{Main|Serial port}}
[[File:RS232 PCI-E.jpg|thumb|[[PCI Express]] x1 card with one RS-232 port on a nine-pin connector]]

In the book ''[[PC 97]] Hardware Design Guide'',<ref name="pc 97">{{cite book |title=PC 97 Hardware Design Guide |date=1997 |publisher=[[Microsoft Press]] |location=Redmond, Washington, USA |isbn=1-57231-381-1}}</ref> [[Microsoft]] deprecated support for the RS-232 compatible serial port of the original IBM PC design. Today, RS-232 has mostly been replaced in personal computers by [[USB]] for local communications. Advantages compared to RS-232 are that USB is faster, uses lower voltages, and has connectors that are simpler to connect and use. Disadvantages of USB compared to RS-232 are that USB is far less immune to [[electromagnetic interference]] (EMI) and that maximum cable length defined by standards is much shorter (15 meters for RS-232 versus 3&ndash;5 meters for USB, depending on the USB version and use of active cables). RS-232 cable lengths of 2000 meters are possible with appropriate line drivers.<ref>{{Cite web|url=https://www.tldp.org/HOWTO/Remote-Serial-Console-HOWTO/serial-distance.html|title=Lengths of serial cables|website=www.tldp.org|access-date=2020-01-01}}</ref><ref>{{Cite book|title=CompTIA A+ Guide to IT technical support|last=Andrews|first=Jean|publisher=Cengage Learning|others=Dark, Joy, West, Jill|year=2020|isbn=978-0-357-10829-1|edition=Tenth|location=Boston, MA, USA|pages=267|oclc=1090438548}}</ref>

In fields such as laboratory automation or surveying, RS-232 devices continue to be used. Some types of [[programmable logic controller]]s, [[variable-frequency drive]]s, [[servo drive]]s, and [[computerized numerical control]] equipment are programmable via RS-232. Computer manufacturers have responded to this demand by re-introducing the [[DE-9M]] connector on their computers or by making adapters available.

RS-232 ports are also commonly used to communicate to [[headless system]]s such as [[server (computing)|server]]s, where no monitor or keyboard is installed, during boot when an [[operating system]] is not yet running and therefore no network connection is possible. A computer with an RS-232 serial port can communicate with the serial port of an [[embedded system]] (such as a [[router (computing)|router]]) as an alternative to monitoring over Ethernet.