|
In telecommunications, RS-232 is a standard for serial communication transmission of data. It formally defines the signals connecting between a ''DTE'' (''data terminal equipment'') such as a computer terminal, and a ''DCE'' (''data circuit-terminating equipment'', originally defined as ''data communication equipment''〔), such as a modem. The RS-232 standard is commonly used in computer serial ports. The standard defines the electrical characteristics and timing of signals, the meaning of signals, and the physical size and pinout of connectors. The current version of the standard is ''TIA-232-F Interface Between Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange'', issued in 1997. An RS-232 serial port was once a standard feature of a personal computer, used for connections to modems, printers, mice, data storage, uninterruptible power supplies, and other peripheral devices. However, RS-232 is hampered by low transmission speed, large voltage swing, and large standard connectors. In modern personal computers, USB has displaced RS-232 from most of its peripheral interface roles. Many computers do not come equipped with RS-232 ports and must use either an external USB-to-RS-232 converter or an internal expansion card with one or more serial ports to connect to RS-232 peripherals. Nevertheless, RS-232 devices are still used, especially in industrial machines, networking equipment and scientific instruments. ==Scope of the standard== The Electronic Industries Association (EIA) standard RS-232-C as of 1969 defines: * Electrical signal characteristics such as voltage levels, signaling rate, timing and slew-rate of signals, voltage withstand level, short-circuit behavior, and maximum load capacitance. * Interface mechanical characteristics, pluggable connectors and pin identification. * Functions of each circuit in the interface connector. * Standard subsets of interface circuits for selected telecom applications. The standard does not define such elements as the character encoding or the framing of characters, or error detection protocols. The character format and transmission bit rate are set by the serial port hardware which may also contain circuits to convert the internal logic levels to RS-232 compatible signal levels. The standard does not define bit rates for transmission, except that it says it is intended for bit rates lower than 20,000 bits per second. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「RS-232」の詳細全文を読む スポンサード リンク
|