Editing Data circuit-terminating equipment

{{Short description|Communications system component}}

[[File:Terminaladapter X.21.jpg|thumb|Terminal adapter for X.21]]
[[File:RS-232 POTS DTE DCE.svg|thumb|Two ''data stations'' (''terminals'', ''stations'') each comprising a DCE and a DTE, connected via a network.]]

A '''data circuit-terminating equipment'''<ref name="TIA_1997_232F"/> ('''DCE''') is a device that sits between the [[data terminal equipment]] (DTE) and a [[data transmission circuit]]. It is also called '''data communication(s) equipment'''<ref name="EIA_1969_RS232C"/><ref name="DIN_44302"/><ref name="MIL-STD-188-100"/> and '''data carrier equipment'''.{{citation needed|date=May 2013|reason=The definition of DCE I have seen most often over the decades is Data Communication Equipment. I would like to see more *historic* references for the various definitions.}} Usually, the DTE device is the [[Terminal (telecommunication)|terminal]] (or [[computer]]), and the DCE is a [[modem]].

In a ''data station'', the DCE performs functions such as [[signal]] conversion, [[Channel coding|coding]], and line clocking and may be a part of the DTE or intermediate equipment.<ref name="DIN_44302"/> Interfacing equipment may be required to couple the DTE into a transmission circuit or [[Communication channel|channel]] and from a transmission circuit or channel into the DTE.

==Usage==
Although the terms are most commonly used with [[RS-232]], several data communication standards define different types of interfaces between a DCE and a DTE. The DCE is a device that communicates with a DTE device in these standards. Standards that use this nomenclature include:
* [[Federal Standard 1037C]], [[MIL-STD-188]]
* [[RS-232]]
* Certain [[ITU-T]] standards in the V series (notably [[ITU-T V.24|V.24]] and [[V.35 (recommendation)|V.35]])
* Certain [[ITU-T]] standards in the X series (notably [[X.21]] and [[X.25]])

A general rule is that DCE devices provide the clock signal (internal clocking) and the DTE device synchronizes on the provided clock (external clocking). [[D-sub]] connectors follow another rule for pin assignment. DTE devices usually transmit on pin connector number 2 and receive on pin connector number 3. DCE devices are just the opposite: pin connector number 2 receives and pin connector number 3 transmits the signals.

When two devices, that are both DTE or both DCE, must be connected together without a modem or a similar media translator between them, a [[crossover cable]] must be used, e.g. a [[null modem]] for RS-232<!--<ref>[http://www.svbug.com/
https://support.google.com/googleplay/thread/[REDACTED]2?hl=arhttps://support.google.com/googleplay/thread/619119484442?hl=arhttps://www.3ssem.com/2019/07/whatsapp-gold.htmlN96]</ref>--> or an [[Ethernet]] crossover cable.

==See also==
* [[Networking hardware]]
* [[Network interface device]]

== References ==
{{reflist|refs=
<ref name="DIN_44302">{{cite book|title=DIN 44302 Datenübertragung - Begriffe |periodical=It - Information Technology|volume=8|number=1–6|year=1966|pages=244–246|doi=10.1524/itit.1966.8.16.244}}</ref>
<ref name="EIA_1969_RS232C">{{cite book|title=EIA standard RS-232-C: Interface between Data Terminal Equipment and Data Communication Equipment Employing Serial Binary Data Interchange |year=1969|publisher=Electronic Industries Association. Engineering Dept|location=Washington|oclc=38637094}}</ref>
<ref name="MIL-STD-188-100">[https://books.google.com/books?id=Xqj6VxVvWXEC&pg=PA24 MIL-STD-188-100, pg. 24, Fig 4.3-1, 1972.]</ref>
<ref name="TIA_1997_232F">{{cite book|title=TIA-232-F Interface Between Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange|year=1997}}</ref>
}}

== External links ==
{{commons category|DCE (Data Circuit-Terminating Equipment)}}
* [https://www.ibm.com/support/knowledgecenter/ssw_aix_71/com.ibm.aix.networkcomm/asynch_modems_dataterm.htm Data Terminating Equipment or Data Circuit-Terminating Equipment speeds], IBM

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[[Category:Data transmission]]
[[Category:Telecommunications equipment]]