Any device is configured as either a DTE or a DCE device.Ĭables between DTE and DCE are different from cables between DCE andĭCE devices. This difference determines, which signal a device expects on which regular computer) is normally equipped with a male D-Sub connector, Data Communications Equipment -DCE- equipment with a female connector. Hubs and Routers could be either DTE or DCE. DCE (Data Communications Equipment) devices are: modems and other equipment. DTE-DTE and DCE-DCE cables are cross cables.ĭCE - DCE is called a 'Tail Circuit Cable'ĭTE (Data Terminal Equipment) devices are: computers, terminals, printers, CSU/DSU, Multiplexers. All DTE-DCE cables are straight through, the pins are connected one to one. The most important difference between these types of devices is that the DCE device supplies the clock signal that paces the communications on the bus. logical '0' (Space) is represented by a positive voltageĭevices that communicate over a serial interface are divided into two classes: DTE and DCE. logical '1' (Mark) is represented by a negative voltage The interface is single ended (connecting only two devices withĮach other), the data rate is less than 20 kbps. Maximum serial cable length is defined: 75 feetĪt 9,600 bps, but today cables up to 1,000 feet are used successfully. A common ground between the PC and the associatedĭevice is necessary. RS232 is a voltage loop interface for two-way (full-duplex)Ĭommunication represented by voltage levels with respect to system

RS 232 serial port (9-pin) DTE-device (PC) RS232 is identical to the standards CCITT V.24/V.28, X.20bis/X.21bis and ISO IS2110. The fourth revision was in 1987(RS-232D also known as EIA-232D). The standard evolved over the years and had the third revision in Standards are now generally indicated as 'EIA' standards. 'RS' means that it is a recommended standard, but the The Electronics Industry Association (EIA) hasĭeveloped standards for data communication.

9 pin serial connection