Data terminal equipment (DTE) is an end instrument that converts

user information User information is information transferred across the functional interface between a source user and a telecommunications system for delivery to a destination user. In telecommunications systems, user information includes user overhead informat ...

into signals or reconverts received signals. These can also be called tail circuits. A DTE device communicates with the

data circuit-terminating equipment A data circuit-terminating equipment (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 and data carrier equipment. Usually, the DTE device i ...

(DCE). The DTE/DCE classification was introduced by IBM. A DTE is the

functional unit In computer engineering, an execution unit (E-unit or EU) is a part of the central processing unit (CPU) that performs the operations and calculations as instructed by the computer program. It may have its own internal control sequence unit (not ...

of a data station that serves as a data source or a data

sink A sink is a bowl-shaped plumbing fixture for washing hands, dishwashing, and other purposes. Sinks have a tap (faucet) that supply hot and cold water and may include a spray feature to be used for faster rinsing. They also include a drain t ...

and provides for the

data communication Data transmission and data reception or, more broadly, data communication or digital communications is the transfer and reception of data in the form of a digital bitstream or a digitized analog signal transmitted over a point-to-point or ...

control function to be performed in accordance with the link protocol. Usually, the DTE device is the

terminal Terminal may refer to: Computing Hardware * Terminal (electronics), a device for joining electrical circuits together * Terminal (telecommunication), a device communicating over a line * Computer terminal, a set of primary input and output dev ...

(or a

computer A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...

emulating a terminal), and the DCE is a

modem A modulator-demodulator or modem is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits data by Modulation#Digital modulati ...

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 In the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine fr ...

), 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 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 A crossover cable connects two devices of the same type, for example DTE-DTE or DCE-DCE, usually connected asymmetrically (DTE-DCE), by a modified cable called a crosslink. Such a distinction between devices was introduced by IBM. The cross ...

s, such as for the

Ethernet Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...

null modem Null modem is a communication method to directly connect two DTEs (computer, terminal, printer, etc.) using an RS-232 serial cable. The name stems from the historical use of RS-232 cables to connect two teleprinter devices or two modems in orde ...

for

RS-232 In telecommunications, RS-232 or Recommended Standard 232 is a standard originally introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ''DTE'' (''data terminal equipment'') such a ...

.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. .

D-sub The D-subminiature or D-sub is a common type of electrical connector. They are named for their characteristic D-shaped metal shield. When they were introduced, D-subs were among the smallest connectors used on computer systems. Description, no ...

connectors follow another rule for 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 In electronics and especially synchronous digital circuits, a clock signal (historically also known as ''logic beat'') oscillates between a high and a low state and is used like a metronome to coordinate actions of digital circuits. A clock sign ...

(internal clocking) and the DTE device synchronizes on the provided clock (external clocking). This term is also generally used in the Telco and

Cisco Cisco Systems, Inc., commonly known as Cisco, is an American-based multinational digital communications technology conglomerate corporation headquartered in San Jose, California. Cisco develops, manufactures, and sells networking hardware, ...

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

connection can also be called a DTE to DTE communication. This communication is done via an

Ethernet crossover cable An Ethernet crossover cable is a crossover cable for Ethernet used to connect computing devices together directly. It is most often used to connect two devices of the same type, e.g. two computers (via their network interface controllers) or two ...

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.

References

External links

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 Telecommunications equipment

Connections

Networking

See also

References

External links