View source for Data terminal equipment

{{Short description|Communications system equipment}}
{{More citations needed|date=July 2013}}
{{Use American English|date = March 2019}}

[[Image:DEC VT100 terminal.jpg|thumb|The [[Digital Equipment Corporation|DEC]] [[VT100]], a widely emulated computer terminal]]
[[File:RS-232 POTS DTE DCE.svg|thumb|DCE and DTE network.]]

'''Data terminal equipment''' ('''DTE''') is an end instrument that converts [[user information]] into signals or reconverts received signals. It is also called '''data processing terminal equipment'''<ref name="DIN_44302"/> or '''tail circuit'''.{{citation needed|date=May 2023}} A DTE device communicates with the [[data circuit-terminating equipment]] (DCE), such as a [[modem]]. The DTE/DCE classification was introduced by [[IBM]].

A DTE is the [[functional unit]] of a data station (''station'', ''terminal'')<ref name="DIN_44302"/> that serves as a data source or a data [[Sink (computing)|sink]] and provides for the [[data communication]] control function to be performed in accordance with the [[link protocol]].

Usually, the DTE device is the [[computer terminal|terminal]] (or a [[computer]] emulating a terminal), and the DCE is a modem or another carrier-owned device. The data terminal equipment may be a single piece of equipment or an interconnected subsystem of multiple pieces of equipment that perform all the required functions necessary to permit users to communicate. A user interacts with the DTE (e.g. through a [[human-machine interface]]), or the DTE may be the user.

==Connections==
Two different types of devices are assumed on each end of the interconnecting cable for a case of simply adding DTE to the topology (e.g. to a [[Ethernet hub|hub]], DCE), which also brings a less trivial case of interconnection of devices of the same type: DTE-DTE or DCE-DCE. Such cases need [[crossover cable]]s, such as for the [[Ethernet]] or [[null modem]] for [[RS-232]].<ref>EIA standard RS-232-C: Interface between Data Terminal Equipment and Data Communication Equipment Employing Serial Binary Data Interchange. Washington: Electronic Industries Association. Engineering Dept. 1969. {{OCLC|8250964307}}.</ref>

[[D-sub]] connectors follow another rule for [[RS-232#Connectors|pin assignment]].
* 25 pin DTE devices transmit on pin 2 and receive on pin 3. 
* 25 pin DCE devices transmit on pin 3 and receive on pin 2.
* 9 pin DTE devices transmit on pin 3 and receive on pin 2. 
* 9 pin DCE devices transmit on pin 2 and receive on pin 3.

==Networking==
A general rule is that DCE devices provide the [[clock signal]] (internal clocking) and the DTE device synchronizes on the provided clock (external clocking).

This term is also generally used in the [[telephone company|Telco]] and [[Cisco]] equipment context to designate a network device, such as terminals, personal computers but also routers and bridges, that's unable or configured not to generate clock signals. Hence a direct PC to PC [[Ethernet]] connection can also be called a DTE to DTE communication. This communication is done via an [[Ethernet crossover cable]] as opposed to a PC to DCE (hub, switch, or bridge) communication which is done via an Ethernet straight cable.

V.35 is a high-speed serial interface designed to support both higher data rates and connectivity between DTEs (data-terminal equipment) or DCEs (data-communication equipment) over digital lines.

== See also ==
{{div col|colwidth=30em}}
* [[Communication endpoint]]
* [[Data circuit-terminating equipment]]
* [[End system]]
* [[Federal Standard 1037C]], [[MIL-STD-188]]
* [[Host (network)]]
* [[Node (networking)]]
* [[Terminal (telecommunication)]]
* [[Serial port]], in depth description of pinouts
{{div col end}}

==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>}}

== External links ==
* [http://www.cisco.com/en/US/docs/internetworking/technology/handbook/Frame-Relay.html Internetworking Technology Handbook, Frame Relay, Cisco Systems] {{Webarchive|url=https://web.archive.org/web/20140202071653/http://www.cisco.com/en/US/docs/internetworking/technology/handbook/Frame-Relay.html |date=2014-02-02 }}

{{Authority control}}

[[Category:Telecommunications equipment]]