RS-232

(communications) A standard developed by the Electronic Industries Association that governs the interface between data processing and data communications equipment, and is widely used to connect microcomputers to peripheral devices.

RS-232

EIA-232

RS-232

(Recommended Standard-232) A TIA/EIA standard for serial transmission. Although employed for numerous other purposes, the RS-232 serial port was widely used on earlier personal computers prior to USB (see serial port). The RS-232 cable limitation of 50 feet can be extended to several hundred feet with high-quality cable.

Although RS-232 defines the signals for 25 lines, many applications use less than a dozen, which is why both DB-25 and DB-9 connectors are used. RS-232 transmits positive voltage for a 0 and a negative voltage for a 1. In 1984, RS-232 was officially renamed TIA/EIA-232-E. See RS-232/485.

Pin Settings for Plug(Reverse order for socket.) ______________________________________ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 _________________ 1 2 3 4 5 6 7 8 9 25 pin 9 pin 1 - PG Protective ground 2 - TD Transmitted data 3 3 - RD Received data 2 4 - RTS Request to send 7 5 - CTS Clear to send 8 6 - DSR Data set ready 6 7 - SG Signal ground 5 8 - CD Carrier detect 1 9 - + voltage (testing) 10 - - voltage (testing) 11 - 12 - SCD Secondary CD 13 - SCS Secondary CTS 14 - STD Secondary TD 15 - TC Transmit clock 16 - SRD Secondary RD 17 - RC Receiver clock 18 - 19 - SRS Secondary RTS 9 pin 20 - DTR Data terminal ready 4 21 - SQD Signal quality detector 22 - RI Ring indicator 9 23 - DRS Data rate select 24 - XTC External clock 25 -