Serial port Wikipedia. In computing, a serial port is a serial communication interface through which information transfers in or out one bit at a time in contrast to a parallel port. Throughout most of the history of personal computers, data was transferred through serial ports to devices such as modems, terminals, and various peripherals. While such interfaces as Ethernet, Fire. Wire, and USB all send data as a serial stream, the term serial port usually identifies hardware more or less compliant to the RS 2. Modern computers without serial ports may require serial to USB converters to allow compatibility with RS 2. Serial ports are still used in applications such as industrial automation systems, scientific instruments, point of sale systems and some industrial and consumer products. Server computers may use a serial port as a control console for diagnostics. Network equipment such as routers and switches often use serial console for configuration. Serial ports are still used in these areas as they are simple, cheap and their console functions are highly standardized and widespread. A serial port requires very little supporting software from the host system. HardwareeditSome computers, such as the IBM PC, use an integrated circuit called a UART. This IC converts characters to and from asynchronous serial form, implementing the timing and framing of data in hardware. Very low cost systems, such as some early home computers, would instead use the CPU to send the data through an output pin, using the bit banging technique. UNIX Serial Port Resources Serial Port Cable Pinouts This content was originally created, collected, and maintained by Stokely Consulting. Say that you take a new Cisco router, switch, or firewall out of the box and hook it up. Does it work No. It isnt like a Linksys or Netgear router. It has no DHCP. Before large scale integration LSI UART integrated circuits were common, a minicomputer or microcomputer would have a serial port made of multiple small scale integrated circuits to implement shift registers, logic gates, counters, and all the other logic for a serial port. Early home computers often had proprietary serial ports with pinouts and voltage levels incompatible with RS 2. Inter operation with RS 2. Low cost processors now allow higher speed, but more complex, serial communication standards such as USB and Fire. Wire to replace RS 2. These make it possible to connect devices that would not have operated feasibly over slower serial connections, such as mass storage, sound, and video devices. Many personal computer motherboards still have at least one serial port, even if accessible only through a pin header. Small form factor systems and laptops may omit RS 2. RS 2. 32 has been standard for so long that the circuits needed to control a serial port became very cheap and often exist on a single chip, sometimes also with circuitry for a parallel port. IBM PC Serial Card with 2. ISA card. A four port serial RS 2. PCI Express 1 expansion card with an octopus cable that breaks the cards DC 3. DE 9 connectors. A converter from USB to an RS 2. IBM XT compatible serial port hardware. SWhAdDNLMG5zdGFuVGlWenmLbJDGd3CABhjZermgcystANA4T6nd0pzV0fSzBRRGOd17A4b8ZLwi6-HESbXI0lDvH6cCGIzAXbYNk-TafNLMvtKyYpMW42W64zoOBqRZQewusrXhL3S25Olu0RBOFA==.png' alt='Console Serial Cable Pinout' title='Console Serial Cable Pinout' />DTE and DCEeditThe individual signals on a serial port are unidirectional and when connecting two devices the outputs of one device must be connected to the inputs of the other. Devices are divided into two categories data terminal equipment DTE and data circuit terminating equipment DCE. A line that is an output on a DTE device is an input on a DCE device and vice versa so a DCE device can be connected to a DTE device with a straight wired cable. Conventionally, computers and terminals are DTE while modems and peripherals are DCE. If it is necessary to connect two DTE devices or two DCE devices but that is more unusual a cross over null modem, in the form of either an adapter or a cable, must be used. Male and femaleedit. DE 9 gender changers, showing both male visible on the left and female DE 9 connectors visible on the rightGenerally, serial port connectors are gendered, only allowing connectors to mate with a connector of the opposite gender. With D subminiature connectors, the male connectors have protruding pins, and female connectors have corresponding round sockets. Either type of connector can be mounted on equipment or a panel or terminate a cable. Connectors mounted on DTE are likely to be male, and those mounted on DCE are likely to be female with the cable connectors being the opposite. However, this is far from universal for instance, most serial printers have a female DB2. DTEs. 3ConnectorseditWhile the RS 2. D type connector, many designers of personal computers chose to implement only a subset of the full standard they traded off compatibility with the standard against the use of less costly and more compact connectors in particular the DE 9 version used by the original IBM PC AT. The desire to supply serial interface cards with two ports required that IBM reduce the size of the connector to fit onto a single card back panel. A DE 9 connector also fits onto a card with a second DB 2. Starting around the time of the introduction of the IBM PC AT, serial ports were commonly built with a 9 pin connector to save cost and space. However, presence of a 9 pin D subminiature connector is not sufficient to indicate the connection is in fact a serial port, since this connector is also used for video, joysticks, and other purposes. Some miniaturized electronics, particularly graphing calculators and hand held amateur and two way radio equipment, have serial ports using a phone connector, usually the smaller 2. Many models of Macintosh favor the related RS 4. German mini DIN connectors, except in the earliest models. The Macintosh included a standard set of two ports for connection to a printer and a modem, but some Power. Book laptops had only one combined port to save space. Since most devices do not use all of the 2. For example, the 9 pin DE 9 connector is used by most IBM compatible PCs since the IBM PC AT, and has been standardized as TIA 5. More recently, modular connectors have been used. Virtual Villagers 5 Full Version Pc. Most common are 8. P8. C connectors, for which the EIATIA 5. Yost Serial Device Wiring Standard4 invented by Dave Yost and popularized by the Unix System Administration Handbook is common on Unix computers and newer devices from Cisco Systems. P1. 0C connectors can be found on some devices as well. Digital Equipment Corporation defined their own DECconnect connection system which is based on the Modified Modular Jack MMJ connector. This is a 6 pin modular jack where the key is offset from the center position. As with the Yost standard, DECconnect uses a symmetrical pin layout which enables the direct connection between two DTEs. Another common connector is the DH1. DE 9 connector and frequently mounted on a free slot plate or other part of the housing. D type adapter cable. A Hirose 3. 56. 0 1. S used for RS 2. Tatung TWN 5. CU tablet computer. Below is a mating 3. P CV connector. PinoutseditThe following table lists commonly used RS 2. Signal. Direction. Connector pin. Name. V. 2. 4 de circuit. Abbreviation. DTEDCEDB 2. DE 9TIA 5. 74MMJ8. P8. C RJ4. 51. P1. C RJ5. 0EIATIA 5. Yost DTEYost DCECyclades6Digi ALTPIN option7National Instruments8Cyclades6Digi9Transmitted Data. Tx. DOut. In. 23. Received Data. 10. Rx. DIn. Out. 32. Data Terminal Ready. DTROut. In. 20. 41. Data Carrier Detect. DCDIn. Out. 81. NA2. Data Set Ready. 10. DSRIn. Out. 66. 61. NA5. 92. Ring Indicator. RIIn. Out. 22. 9NANANANANA2. Request To Send. 10. RTSOut. In. 47. NA8. Practicing Power Now Pdf. Clear To Send. 10. CTSIn. Out. 58. NA7. Signal Ground. 10. GCommon. 75. 3, 4. Protective Ground. PGCommon. 1NANANANANANA3.