Editing NMEA 0183 (section)

==Details==
The electrical standard that is used is [[EIA-422]], also known as RS-422, although most hardware with NMEA-0183 outputs are also able to drive a single [[EIA-232]] port. The standard calls for optically isolated inputs. There is no requirement for isolation for the outputs.

The NMEA 0183 standard uses a simple [[ASCII]], [[serial communications]] protocol that defines how data are transmitted in a "sentence" from one "talker" to multiple "listeners" at a time. Through the use of intermediate expanders, a talker can have a unidirectional conversation with a nearly unlimited number of listeners, and using [[multiplexers]], multiple sensors can talk to a single computer port.

At the [[application layer]], the standard also defines the contents of each sentence (message) type, so that all listeners can parse messages accurately.

While NMEA 0183 only defines an RS-422 transport, there also exists a de facto standard in which the sentences from NMEA 0183 are placed in [[User Datagram Protocol|UDP]] datagrams (one sentence per packet) and sent over an IP network.

The NMEA standard is proprietary and sells for at least US$2000 (except for members of the NMEA) as of September 2020.<ref name="NMEA0183">{{cite web |url=http://www.nmea.org/content/nmea_standards/nmea_0183_v_410.asp |title=Publications and Standards from the National Marine Electronics Association (NMEA) / NMEA 0183 |publisher=NMEA |date=November 2008 |access-date=2013-10-21 |archive-url=https://web.archive.org/web/20131021183159/http://www.nmea.org/content/nmea_standards/nmea_0183_v_410.asp |archive-date=2013-10-21 |url-status=dead }}</ref><ref>{{Cite web|title=National Marine Electronics Association - NMEA|url=https://www.nmea.org/content/STANDARDS/NMEA_0183_Standard|access-date=2020-09-24|website=www.nmea.org|archive-date=2022-03-31|archive-url=https://web.archive.org/web/20220331214516/https://www.nmea.org/content/STANDARDS/NMEA_0183_Standard|url-status=dead}}</ref> However, much of it has been reverse-engineered from public sources.<ref name="NMEA revealed">{{Cite web |url=https://gpsd.gitlab.io/gpsd/NMEA.html |title=NMEA Revealed |last=Raymond |first=Eric S. |date=March 2019}}</ref><ref>{{cite web|url=http://www.gpsinformation.org/dale/nmea.htm|title=NMEA data |author=Dale DePriest |archive-url=https://web.archive.org/web/20201020015948/http://www.gpsinformation.org/dale/nmea.htm |access-date=2020-10-20|archive-date=2020-10-20 }}</ref>