Data terminal equipment
Encyclopedia
Data Terminal Equipment (DTE) is an end instrument
that converts user information
into signals or reconverts received signals. These can also be called tail circuits. A DTE device communicates with the data circuit-terminating equipment
(DCE). The DTE/DCE classification was introduced by IBM
.
Basically, 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.
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
s, such as for the Ethernet
or null modem
for RS-232
.
A DTE is the functional unit of a data station that serves as a data source or a data sink
and provides for the data communication control function to be performed in accordance with the link protocol
.
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.
Usually, the DTE device is the terminal
(or a computer
emulating a terminal), and the DCE is a modem
or another carrier-owned device.
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.
This term is also generally used in the 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 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.
End instrument
In telecommunications an end instrument is an equipment connected to the wires at the end of a telecommunications link. In most cases, this is a telephone. End instruments that relate to DTE include Printers, Computers, barcode readers, Automated Teller Machines and the console ports of routers....
that converts user information
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 information....
into signals or reconverts received signals. These can also be called tail circuits. A DTE device communicates with the data circuit-terminating equipment
Data circuit-terminating equipment
A data circuit-terminating equipment is a device that sits between the data terminal equipment and a data transmission circuit. It is also called data communications equipment and data carrier equipment...
(DCE). The DTE/DCE classification was introduced by IBM
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
.
Basically, 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.
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
Ethernet hub
An Ethernet hub, active hub, network hub, repeater hub or hub is a device for connecting multiple Ethernet devices together and making them act as a single network segment. A hub works at the physical layer of the OSI model. The device is a form of multiport repeater...
, 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
Crossover cable
A crossover cable connects two devices of the same type, for example DTE-DTE or DCE-DCE, usually connected asymmetrically , by a modified cable called a crosslink...
s, such as for the Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
or null modem
Null modem
Null modem is a communication method to connect two DTEs directly using an RS-232 serial cable. The name stems from the historical use of the RS-232 cable to connect two teleprinter devices to modems in order to communicate with one another; null modem communication was possible by instead using...
for RS-232
RS-232
In telecommunications, RS-232 is the traditional name for a series of standards for serial binary single-ended data and control signals connecting between a DTE and a DCE . It is commonly used in computer serial ports...
.
A DTE is the functional unit of a data station that serves as a data source or a data sink
Sink (computing)
In computing, a sink or event sink is a class or function designed to receive incoming events from another object or function. This is commonly implemented in C++ as callbacks. Object-oriented languages, such as Java and C#, have built-in support for sinks by allowing events to be fired to...
and provides for the data communication control function to be performed in accordance with the link protocol
Link protocol
In communications, a link protocol is a method and specification for transmission of data from one node on a local network or network link to another node on the same link...
.
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
Human-machine interface
Human-machine interface is the part of the machine that handles the Human-machine interaction- Overview :In complex systems, the human-machine interface is typically computerized. The term Human-computer interface refers to this kind of systems....
), or the DTE may be the user.
Usually, the DTE device is the terminal
Computer terminal
A computer terminal is an electronic or electromechanical hardware device that is used for entering data into, and displaying data from, a computer or a computing system...
(or a computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
emulating a terminal), and the DCE is a modem
Modem
A modem is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data...
or another carrier-owned device.
A general rule is that DCE devices provide the clock signal
Clock signal
In electronics and especially synchronous digital circuits, a clock signal is a particular type of signal that oscillates between a high and a low state and is utilized like a metronome to coordinate actions of circuits...
(internal clocking) and the DTE device synchronizes on the provided clock (external clocking). D-sub 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.
This term is also generally used in the Telco
Telephone company
A telephone company is a service provider of telecommunications services such as telephony and data communications access. Many were at one time nationalized or state-regulated monopolies...
and Cisco
Cisco
Cisco may refer to:Companies:*Cisco Systems, a computer networking company* Certis CISCO, corporatised entity of the former Commercial and Industrial Security Corporation in Singapore...
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 PC to PC Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
connection can also be called a DTE to DTE communication. This communication is done via an Ethernet crossover cable
Ethernet crossover cable
An Ethernet crossover cable is a type of Ethernet cable used to connect computing devices together directly. Normal straight through or patch cables were used to connect from a host network interface controller to a network switch, hub or router.A cable with connections that "cross over" was used...
as opposed to a PC to DCE (hub, switch, or bridge) communication which is done via an Ethernet straight cable.
See also
- Federal Standard 1037CFederal Standard 1037CFederal Standard 1037C, titled Telecommunications: Glossary of Telecommunication Terms is a United States Federal Standard, issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended....
, MIL-STD-188MIL-STD-188MIL-STD-188 is a series of U.S. military standards relating to telecommunications.-Purpose:Faced with “past technical deficiencies in telecommunications systems and equipment and software…that were traced to basic inadequacies in the application of telecommunication standards and to the lack of a... - RS-232RS-232In telecommunications, RS-232 is the traditional name for a series of standards for serial binary single-ended data and control signals connecting between a DTE and a DCE . It is commonly used in computer serial ports...
- Data circuit-terminating equipmentData circuit-terminating equipmentA data circuit-terminating equipment is a device that sits between the data terminal equipment and a data transmission circuit. It is also called data communications equipment and data carrier equipment...
- Terminal (telecommunication)Terminal (telecommunication)In the context of telecommunications, a terminal is a device which is capable of communicating over a line. Examples of terminals are telephones, fax machines, and network devices - printers and workstations....
- Internetworking Technology Handbook, Frame Relay, Cisco Systems