 A male DE-9 connector used for a serial port on a PC style computer. In computing, a serial port is a serial communication physical interface through which information transfers in or out one bit at a time (contrast parallel port). Throughout most of the history of personal computers, data transfer through serial ports connected the computer to devices such as terminals or modems. Mice, keyboards, and other peripheral devices also connected in this way. Image File history File linksMetadata Download high resolution version (1310x982, 279 KB) Summary Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Serial port Metadata This file contains additional information, probably added from the digital camera or scanner...
Image File history File linksMetadata Download high resolution version (1310x982, 279 KB) Summary Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Serial port Metadata This file contains additional information, probably added from the digital camera or scanner...
In electrical and mechanical trades and manufacturing, each of a pair of mating connectors or fasteners is conventionally assigned the designation male or female. ...
It has been suggested that DE-9 be merged into this article or section. ...
This article or section does not cite its references or sources. ...
RAM (Random Access Memory) Look up computing in Wiktionary, the free dictionary. ...
In telecommunications and computer science, serial communications is the process of sending data one bit at one time, sequentially, over a communications channel or computer bus. ...
This article is about the unit of information. ...
It has been suggested that LPT, Centronics and IEEE 1284 be merged into this article or section. ...
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. ...
A modem (from modulate and demodulate) 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. ...
Operating a mechanical 1: Pulling the mouse turns the ball. ...
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It has been suggested that this article or section be merged into Computer hardware. ...
While such interfaces as Ethernet, FireWire, and USB all send data as a serial stream, the term "serial port" usually identifies hardware more or less compliant to the RS-232 standard, intended to interface with a modem or with a similar communication device. Ethernet is a large, diverse family of frame-based computer networking technologies that operates at many speeds for local area networks (LANs). ...
The 6-pin and 4-pin FireWire Connectors The alternative ethernet-style cabling used by 1394c FireWire is Apple Inc. ...
Note: USB may also mean upper sideband in radio. ...
In computing, the term stream is used in a number of ways, in all cases referring to a succession of data elements made available over time. ...
RS-232 (also referred to as EIA RS-232C or V.24) is a standard for serial binary data interchange between a DTE (Data terminal equipment) and a DCE (Data communication equipment). ...
A modem (from modulate and demodulate) 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. ...
For many computer peripheral devices the USB interface has replaced the serial port — as of 2007, most modern computers are connected to devices through a USB connection, and often don't even have a serial port. The serial port is omitted for cost savings, and is considered to be a legacy port. However serial ports can still be found in industrial automation systems and some industrial and consumer products. Network equipment (such as routers and switches) often have serial ports for configuration. Serial ports are still used in these areas as they are simple, cheap and allow interoperability between devices. The disadvantage is that setting up serial connections may require expert knowledge and complex commands if poorly implemented. A USB Series “A†plug, the most common USB plug Universal Serial Bus (USB) is a serial bus standard to interface devices. ...
2007 is a common year starting on Monday of the Gregorian calendar. ...
A legacy port is a port or connector on a PC that is considered fully or partially obsolete. ...
Hardware
Some computers, such as the IBM PC, used an integrated circuit called a UART, that converted characters to (and from) asynchronous serial form, and automatically looked after the timing and framing of data. 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 so-called bit-banging technique. IBM PC (IBM 5150) with keyboard and green screen monochrome monitor (IBM 5151), running MS-DOS 5. ...
Integrated circuit of Atmel Diopsis 740 System on Chip showing memory blocks, logic and input/output pads around the periphery Microchips with a transparent window, showing the integrated circuit inside. ...
A UART or universal asynchronous receiver-transmitter is a piece of computer hardware that translates between parallel bits of data and serial bits. ...
It has been suggested that this article or section be merged with Start-stop transmission. ...
The asynchronous start-stop is the more common of two basic modes of teletypewriter operation, allowing a common means of encoding characters over a serial link such as RS-232. ...
Children playing on a Amstrad CPC 464 in the 1980s. ...
Die of an Intel 80486DX2 microprocessor (actual size: 12×6. ...
Energy Input: The energy placed into a reaction. ...
Bit-banging is a technique for serial communications to use software instead of dedicated hardware such as a UART or shift register. ...
While the RS-232 standard originally specified a 25-pin 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). Presence of a nine pin D-subminiature connector is neither necessary nor sufficient to indicate use of a serial port. It has been suggested that DE-9 be merged into this article or section. ...
The D-subminiature or D-sub is a common type of electrical connector used particularly in computers (i. ...
IBM PC (IBM 5150) with keyboard and green screen monochrome monitor (IBM 5151), running MS-DOS 5. ...
It has been suggested that DE-9 be merged into this article or section. ...
Many models of Macintosh favored the related (but faster) RS-422 standard, often using German Mini-DIN connectors. The first Macintosh computer, introduced in 1984, upgraded to a 512K Fat Mac. The Macintosh or Mac, is a line of personal computers designed, developed, manufactured, and marketed by Apple Computer. ...
EIA-422 (formerly RS-422) is a serial data communication protocol which specifies 4-wire, full-duplex, differential line, multi-drop communications. ...
The mini-DIN connectors are a family of multi-pin Electrical connectors used in a variety of applications. ...
Some miniaturized electronics, particularly graphing calculators and to a lesser extent handheld amateur and two-way radio equipment, have serial ports using a jack plug connector, usually the smaller 2.5 or 3.5mm connectors. A typical graphing calculator. ...
Amateur radio station with modern solid-state transceiver featuring LCD display and DSP capabilities Amateur radio, often called ham radio, is a hobby that uses various types of radio broadcasting equipment to communicate with other radio amateurs for public service, recreation and self-training. ...
Motorola HT1000 hand-held two-way radio A two-way radio is a radio that can both transmit and receive (a transceiver), unlike a broadcast receiver which only receives content one way. ...
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In recent years, advanced electronics has made economical higher-speed serial communications possible, so newer serial communication standards such as USB and FireWire have started to supplant RS-232. These make it possible to connect devices that would not have operated feasibly over slower serial connections, such as storage devices, sound devices, and video devices. A USB Series “A†plug, the most common USB plug Universal Serial Bus (USB) is a serial bus standard to interface devices. ...
The 6-pin and 4-pin FireWire Connectors The alternative ethernet-style cabling used by 1394c FireWire is Apple Inc. ...
Operating systems usually use a symbolic name to refer to the serial ports of a computer. Unix-like operating systems usually label the serial port devices /dev/tty* (tty an abbreviation for teletype) where * represents a string identifying the terminal device; the syntax of that string depends on the operating system and the device. The Microsoft MS-DOS and Windows environments refer to serial ports as COM ports: COM1, COM2, etc. Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ...
Microsofts disk operating system, MS-DOS, was Microsofts implementation of DOS, which was the first popular operating system for the IBM PC, and until recently, was widely used on the PC compatible platform. ...
Windows redirects here. ...
COM is the original, yet still common, name of the serial port interface on IBM PC-compatible computers. ...
When a laptop does not have a serial port, two popular substitutes are USB adapters and PCMCIA cards. USB adapters often fail to work with older "legacy" devices. A more expensive PC card adaptor provides a real (hardware) serial port. If communication with RS 232 devices is critical, a physical RS 232 port will generally provide better compatibility with "legacy" software. The PCMCIA is the Personal Computer Memory Card International Association, an industry trade association that creates standards for notebook computer peripheral devices. ...
Settings A multitude of software settings are required for serial connections used for asynchronous start-stop communication, most commonly setting speed, number of data bits per character, parity, and number of stop bits per character. In modern serial ports using a UART integrated circuit, all settings are usually software-controlled; hardware from the 1980s and earlier may require setting switches or jumpers on a circuit board. One of the simplifications made in such serial bus standards as Ethernet, FireWire, and USB is that many of those parameters have fixed values so that users can not and need not change the configuration; the speed is either fixed or automatically negotiated. The asynchronous start-stop is the more common of two basic modes of teletypewriter operation, allowing a common means of encoding characters over a serial link such as RS-232. ...
A UART or universal asynchronous receiver-transmitter is a piece of computer hardware that translates between parallel bits of data and serial bits. ...
Speed Serial ports use two-level (binary) signalling, so the data rate in bits per second is equal to the symbol rate in baud. Common bit rates per second for asynchronous start/stop communication are 300, 1200, 2400, 9600, 19200 baud, etc. These rates are based on multiples of the rates for electromechanical teleprinters. The port speed and device speed must match, though some devices may automatically detect the speed of the serial port. Though the RS-232 standard is formally limited to 20,000 bits per second, serial ports on popular personal computers allow settings up to 115,200 bits per second; the capability to set a bit rate does not imply that a working connection will result. Not all bit rates are possible with all serial ports. Some special-purpose protocols such as MIDI for musical instrument control, or OBD diagnostics for automobiles, use serial data rates other than the above series. In telecommunications and electronics, baud (pronounced unit symbol Bd), is a measure of the symbol rate; that is, the number of distinct symbol changes (signalling events) made to the transmission medium per second in a digitally modulated signal. ...
Teletype machines in World War II A teleprinter (teletypewriter, teletype or TTY for TeleTYpe/TeleTYpewriter) is a now largely obsolete electro-mechanical typewriter which can be used to communicate typed messages from point to point through a simple electrical communications channel, often just a pair of wires. ...
Musical Instrument Digital Interface, or MIDI, is a system designed to transmit information between electronic musical instruments. ...
On-Board Diagnostics, or OBD, in an automotive context, is a generic term referring to a vehicles self-diagnostic and reporting capability. ...
The speed includes bits for framing (stop bits, parity, etc.) and so the effective data rate is lower than the bit transmission rate. For example for 8-N-1 encoding only 80% of the bits are available for data (for every eight bits of data, two more framing bits are sent). 8-N-1 is a common shorthand notation for a Serial port parameter setting or configuration in asynchronous mode, in which there are eight (8) data bits, no (N) parity bit, and one (1) stop bit. ...
Data Bits The number of data bits in each character can be 5 (for Baudot Code), 6 (rarely used), 7 (for true ASCII), 8 (for any kind of data, as this matches the size of a byte), or 9 (rarely used). 8 data bits are almost universally used in newer applications. 5 or 7 bits generally only make sense with older equipment such as teleprinters. The Baudot code, named after its inventor Émile Baudot, is a character set predating EBCDIC and ASCII and used originally and primarily on teleprinters. ...
Image:ASCII fullsvg There are 95 printable ASCII characters, numbered 32 to 126. ...
In computer science a byte (pronounced bite) is a unit of measurement of information storage, most often consisting of eight bits. ...
Teletype machines in World War II A teleprinter (teletypewriter, teletype or TTY for TeleTYpe/TeleTYpewriter) is a now largely obsolete electro-mechanical typewriter which can be used to communicate typed messages from point to point through a simple electrical communications channel, often just a pair of wires. ...
Most serial communications designs send the data bits within each byte LSB (Least Significant Bit) first. This standard is also referred to as "little endian". Also possible, but rarely used, is "big endian" or MSB (Most Significant Bit) first serial communications (see Endianness). The order of bits is not usually configurable. In computing, endianness is the byte (and sometimes bit) ordering in memory used to represent some kind of data. ...
Parity Parity is a method of detecting some errors in transmission. Where parity is used with a serial port, an extra data bit is sent with each data character, arranged so that the number of 1 bits in each character, including the parity bit, is always odd or always even. If a byte is received with the wrong number of 1 bits, then it must have been corrupted. If parity is correct there may have been no errors or an even number of errors. Electromechanical teleprinters were arranged to print a special character when received data contained a parity error, to allow detection of messages damaged by line noise. A single parity bit does not allow implementation of error correction on each character, and communication protocols working over serial data links will have higher-level mechanisms to ensure data validity and request retransmission of data that has been incorrectly received. Look up Parity in Wiktionary, the free dictionary Parity is a concept of equality of status or functional equivalence. ...
A parity bit is a binary digit that indicates whether the number of bits with value of one in a given set of bits is even or odd. ...
In computer science and information theory, error correction consists of using methods to detect and/or correct errors in the transmission or storage of data by the use of some amount of redundant data and (in the case of transmission) the selective retransmission of incorrect segments of the data. ...
In the field of telecommunications, a communications protocol is the set of standard rules for data representation, signalling, authentication and error detection required to send information over a communications channel. ...
The parity bit in each character can be set to none (N), odd (O), even (E), mark (M), or space (S). None means that no parity bit is sent at all. Mark parity means that the parity bit is always set to the mark signal condition (logical 1) and likewise space parity always sends the parity bit in the space signal condition. Aside from uncommon applications that use the 9th (parity) bit for some form of addressing or special signalling, mark or space parity is uncommon, as it adds no error detection information. Odd parity is more common than even, since it ensures that at least one state transition occurs in each character, which makes it more reliable. The most common parity setting, however, is "none", with error detection handled by a communication protocol.
Stop bits Stop bits sent at the end of every character allow the receiving signal hardware detect the end of a character and to resynchronise with the character stream. Electronic devices usually use one stop bit. Occasionally, and especially if slow electromechanical devices are used, such as teleprinters, one-and-one half or two stop bits are required. Teletype machines in World War II A teleprinter (teletypewriter, teletype or TTY for TeleTYpe/TeleTYpewriter) is a now largely obsolete electro-mechanical typewriter which can be used to communicate typed messages from point to point through a simple electrical communications channel, often just a pair of wires. ...
Conventional notation The D/P/S conventional notation specifies the framing of a serial connection. The most common usage on microcomputers is 8/N/1 (8N1). This specifies 8 data bits, no parity, 1 stop bit.
In this notation, the parity bit is not included in the data bits. 7/E/1 (7E1) means that an even parity bit is added to the seven data bits for a total of eight bits between the start and stop bits. If a receiver of a 7/E/1 stream is expecting an 8/N/1 stream, half the possible bytes will be interpreted as having the high bit set.
Flow control A serial port may use signals in the interface to pause and resume the transmission of data. For example, a slow printer might need to handshake with the serial port to indicate that data should be paused while the mechanism advances a line. Common hardware handshake signals use the RS-232 RTS/CTS, DTR/DSR signal circuits. See the separate article on transmit flow control. In information technology, telecommunications, and related fields, handshaking is an automated process of negotiation that dynamically sets parameters of a communications channel established between two entities before normal communication over the channel begins. ...
pwned like a n00b on crack In data communications systems, transmit flow control is control of the rate at which data are transmitted from a terminal so that the data can be received by another terminal. ...
Another method of flow control may use special characters such as XON/XOFF to control the flow of data. The XON/XOFF characters are sent by the receiver to the sender to control when the sender will send data, that is, these characters go in the opposite direction to the data being sent. The XON character tells the sender that the receiver is ready for more data. The XOFF character tells the sender to stop sending characters until the receiver is ready again. XON/XOFF is software data flow communications protocol for controlling the flow of data between computers and other devices. ...
If the control characters are part of the data stream, they must be sent as part of an escape sequence to prevent data from being interpreted as flow control. Since no extra signal circuits are required, XON/XOFF flow control can be done on a 3 wire interface. To meet Wikipedias quality standards, this article or section may require cleanup. ...
Software A virtual serial port is an emulation of the standard serial port. This port is created by software which enable extra serial ports in an operating system without additional hardware installation (such as expansion cards, etc.). Unlike a physical serial port the virtual one can be assigned any name (COM255, VSP33, etc.). It is possible to create unlimited number of virtual serial ports in your PC. The only limitation is the computer performance, as it may require a substantial amount of resources to emulate large numbers of serial ports. The current version of the article or section reads like an advertisement. ...
Fitting an expansion card into a motherboard An expansion card in computing is a printed circuit board that can be inserted into an expansion slot of a computer motherboard to add additional functionality to a computer system. ...
Virtual serial port emulates all serial port functionality, including Baud rate, Data bits, Parity bits, Stop bits, etc. Additionally it allows controlling the data flow, emulating all signal lines (DTR/DSR/CTS/RTS/DCD/RI) and customizing pinout. The current version of the article or section reads like an advertisement. ...
In telecommunications and electronics, baud (pronounced unit symbol Bd), is a measure of the symbol rate; that is, the number of distinct symbol changes (signalling events) made to the transmission medium per second in a digitally modulated signal. ...
Virtual serial port emulation can be useful in case there is a lack of available physical serial ports or they do not meet the current requirements. For instance, virtual serial ports can help you share data between several applications from one GPS device connected to serial port. Another option is to communicate with any other serial devices via internet or LAN as if they are locally connected to computer (Serial-over-Ethernet technology). You can establish connection between two computers or applications via emulated null-modem link. Most of the available virtual serial port emulators are compatible with recent versions of Microsoft Windows and some of them run under Windows CE, Windows Mobile and Pocket PC. Over fifty GPS satellites such as this NAVSTAR have been launched since 1978. ...
See also - RS-232 This page describes the details of the standard including pin assignments.
- Parallel port
- Teleprinter describes the history of the devices that the serial port was developed to drive.
Image File history File links Wikibooks-logo-en. ...
Wikibooks logo Wikibooks, previously called Wikimedia Free Textbook Project and Wikimedia-Textbooks, is a wiki for the creation of books. ...
RS-232 (also referred to as EIA RS-232C or V.24) is a standard for serial binary data interchange between a DTE (Data terminal equipment) and a DCE (Data communication equipment). ...
It has been suggested that LPT, Centronics and IEEE 1284 be merged into this article or section. ...
Teletype machines in World War II A teleprinter (teletypewriter, teletype or TTY for TeleTYpe/TeleTYpewriter) is a now largely obsolete electro-mechanical typewriter which can be used to communicate typed messages from point to point through a simple electrical communications channel, often just a pair of wires. ...
External links - Serial interfaces ports of modern and obsolete computers
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