This article details the connections (pinouts) of EIA standard RS-232C. This connector consists of a D-shaped plug with 25 pins in two rows: 13 pins in the upper row and 12 in the lower. This interface is commonly used by devices that require a serial interface to a computer; these devices include modems, terminals, serial printers, and such specialized devices as bar-code scanners. In addition, this articles gives the pinouts of the nine-pin DB-9P connector, which is a nine-pin version of the RS-232 that is commonly used in AT and AT-compatible computers.
+o Nine-pin DB-9P convention
+o Common abbreviations of signal names
+o Abbreviations of RS-232 signal names
+o Equivalent CCITT signal-number designations
+o Signal direction (as appropriate)
+o Signal description
Please note that in this table, DTE stands for ``data terminal equipment'' and refers to terminal-type equipment such as a PC or a terminal, whereas DCE stands for ``data communications equipment'' and refers to modems and modem-type equipment. _D_B_-_2_5 _D_B_-_9 _C_o_m_m_o_n _P_i_n _# _P_i_n _# _N_a_m_e _E_I_A _C_C_I_T_T_D_T_E_-_D_C_E_D_e_s_c_r_i_p_t_i_o_n 1 FG AA 101 -- Frame ground 2 3 TD BA 103 -> Transmitted data 3 2 RD BB 104 <- Received data 4 7 RTS CA 105 -> Request to send 5 8 CTS CB 106 <- Clear to send 6 6 DSR CC 107 <- Data set ready 7 5 SG AB 102 -- Signal ground 8 1 DCD CF 109 <- Data carrier detect 9 -- -- -- -- Positive DC test voltage 10 -- -- -- -- Negative DC test voltage 11 QM -- -- <- Equalizer mode 12 SDCD SCF 122 <- Secondary carrier detect 13 SCTS SCB 121 <- Secondary clear to send 14 STD SBA 118 -> Secondary transmitted data 15 TC DB 114 <- Transmitter clock 16 SRD SBB 119 <- Secondary receiver clock 17 RC DD 115 -> Receiver clock 18 DCR -- -- <- Divided clock receiver 19 SRTS SCA 120 -> Secondary request to send 20 4 DTR CD 108.2 -> Data terminal ready 21 SQ CG 110 <- Signal quality 22 9 RI CE 125 <- Ring indicator 23 -- CH 111 -> Data rate selector 24 TC DA 113 <- Transmitted clock 25