What is DTE & DCE and its Definition?

Definition: DTE & DCE

DTE

DTE is acronym for Data Terminal Equipment.

Examples of DTE is computers, printers & terminals.

DCE

DCE is acronym for Data Communication Equipment.

Examples of DCE is modems.

Wiring

Wiring a cable for DTE to DCE communication is easy. All wires goes straight from pin x to pin x.

But wiring a cable for DTE to DTE (null modem) or DCE to DCE requires that some wires are crossed. A signal should be wire from pin x to the opposite signal at the other end. With opposite signals I mean for example Transmit & Send.

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DCE equipment is typically a modem or other type of communication device. The DCE sits between the DTE (data terminal equipment) and a transmission circuit such as a phone line. Originally, the DTE was a dumb terminal or printer, but today it is a computer, or a bridge or router that interconnects local area networks. In an IBM mainframe environment, a communication controller and a link-attached cluster controller are examples of DTEs.

A DCE provides a connection for the DTE into a communication network and back again. In addition, it terminates and provides clocking for a circuit. When analog telephone lines are the communication media, the DCE is a modem. When the lines are digital, the DCE is a CSU/DSU (channel service unit/data service unit).

DTE and DCE interfaces are defined by the physical layer in the OSI (Open Systems Interconnection) model. The most common standards for DTE/DCE devices are EIA (Electronic Industries Association) RS-232-C and RS-232-D. Outside the United States, these standards are the same as the V.24 standard of the CCITT (Consultative Committee for International Telegraphy and Telephony). Other DTE/DCE standards include the EIA RS-366-A, as well as the CCITT X.20, X.21, and V.35 standards. The later standards are used for high-speed communication over telephone lines.

DTE and DCE devices send and receive data on separate wires that terminate at a 25-pin connector. It is useful to know that DTE devices transmit on pin connector 2 and receive on pin 3. DCE devices are just the opposite-pin 3 transmits and pin 2 receives.