FILE: RS232.TXT IBM-PC ====== RS-232 address table is found at offset 00H in the BIOS data area BIOS serial-port service routines are accessed through interrupt 14H COM1 3F8H IRQ4 COM2 2F8H IRQ3 COM3 3E8H IRQ4 COM4 2E8H IRQ3 IBM PC Serial Ports: ==================== PC, XT 25-pin serial port DB-25P connector configured as DTE (Data- Terminal-Equipment) RS-232c standard: Pin Description Direction 1 Chassis ground - 2 Transmit data TX Out 3 Receive data RX In 4 Request to send RTS Out 5 Clear to send CTS In 6 Data set ready DSR In 7 Signal Ground SG - 8 Data Carrier detect DCD In 9 [+Transmit Current loop] 11 [-Transmit Current loop] 18 [+Rec.Current loop 20ma] 20 Data terminal ready DTR Out 22 Ring indicator RI In 25 [-Rec.Current loop 20ma] A modem or printer would have a DCE (Data-Communication-Equipment) connector, with the functions of pins 2-3, 4-5, and 6-20 reversed; and the directions of DCD and RI reversed as well. AT 9-pin serial port connector (DB-9P) configured as DTE device: Pin Description Direction 1 Data carrier detect DCD In 2 Receive data RX In 3 Transmit data TX Out 4 Data terminal ready DTR Out 5 Signal Ground SG - 6 Data Set Ready DSR In 7 Request to send RTS Out 8 Clear to send CTS In 9 Ring indicator RI In DEC Serial Ports: ================== 25 Pin Pin Function Abr FDXA FDXB FDXC ------------------------------------------------------------------------------- 1 Protective Ground PGND X X X 2 Transmit Data TXD X X X 3 Receive Data RXD X X X 4 Request to Send RTS X X X 5 Clear to Send CTS X X X 6 Data Set Ready DSR X X X 7 Signal Ground SGND X X X 8 Carrier Detect CD X X 9 Reserved 10 Reserved 11 Unassigned 12 Secondary Carrier Detect SI X (Speed Indicator) 13 Secondary Clear to Send SCTS X 14 Secondary Transmit Data STXD X 15 Transmit Clock TSET X 16 Secondary Receive Data SRXD 17 Receiver Clock RSET X 18 Unassigned 19 Secondary Request to Send SRTS X 20 Data Terminal Ready DTR X X X 21 Signal Quality Detect 22 Ring Indicater RI - - - 23 Data signal rate select SPDS X (Speed Select) 24 Transmit clock 25 Unassigned ------------------------------------------------------------------------------- Pin Abr RS232c IBMPC VT220 VT320 ------------------------------------------------------------------------------- 1 PGND x x 2 TXD x x x x 3 RXD x x x x 4 RTS x x x x 5 CTS x x x x 6 DSR x x x x 7 SGND x x x x 8 CD x x x x 9 +TXD Curlp x 10 11 -TXD Curlp x 12 SI x x 13 SCTS 14 STXD 15 TSET 16 SRXD 17 RSET 18 +RXD.Crtlp x 19 SRTS 20 DTR x x x x 21 22 RI x x 23 SPDS x x 24 25 -RXD.Crtlp x ------------------------------------------------------------------------------- 9 Pin Printer Serial Port (VT220) Pin Function Abr -------------------------------------- 1 Protective Ground PGND 2 Transmit Data TXD 3 Receive Data RXD 4 Request to Send RTS 5 Data Terminal Ready DTS 6 Data Set Ready DSR 7 Signal Ground SGND 8 9 -------------------------------------- 6 Pin Serial Port +------------+ |1 2 3 4 5 6 | +-------+ +-+ +--+ Pin Function Abr -------------------------------------- 1 Data Terminal Ready DTS 2 Transmit Data TXD+ 3 Transmit Signal Ground TDX- 4 Receive Signal Ground RXD- 5 Receive Data RXD+ 6 Data Set Ready DSR -------------------------------------- 20ma Port Interface Signals Pin Function ---------------- 1 -12v 2 Transmit - 3 Receive - 5 Transmit + 7 Receive + 8 Ground ---------------- SERIAL CABLES ============= FX DATA TRANSFER CABLES P1 For Toshiba T1000se ======================= ========================== FEMALE CONNECTORS 9-PIN 25-PIN 25-PIN 9-PIN PC TERMINAL CABLE --------------------------- ---------------------- 5 7 - 7 5 GND - GND 9 PIN 25 PIN 3 2 - 3 2 TRX - RCX FEMALE MALE 7 4 - 5 8 RTS - CTS ------ ------ 6 6 - 20 4 DSR - DTR 2 ----------- 3 2 3 - 2 3 RCX - TRX 3 ----------- 2 8 5 - 4 7 CTS - RTS 5 ----------- 7 4 20 - 6 6 DTR - DSR P2 FOR CRACK MONITOR - AMSTRAD P3 FOR CRACK MONITOR - TOSHIBA ================================== ================================== DATATAKER PC DATATAKER PC --------------------- --------------------- 9 PIN 25 PIN 9 PIN 9 PIN MALE FEMALE MALE FEMALE ------ ------ ------ ------ 1,2 ----------- 1,7 1,2 ----------- 5 3 ----------- 3 3 ----------- 2 4 ----------- 2 4 ----------- 3 5,7 5,7 4,5 7,8 6,8,20 1,4,6 G206U MAGNETOMETER CABLE => PC ============================== 18 PIN 9 PIN 25 PIN CONNECTOR RS232 RS232 ------------------------------- A B C D 5 7 E F G 7+8 4+5 H J K L M N T 2 3 U 3 2 S R TERM PRINTER COMS PRN VT220 9PIN to EPSON 6PIN DIN to PC100B 25PIN to PC100B 25PIN FEMALE MALE FEMALE MALE -------------------------------------------------------------------- 1 - 6 - 1 - 1 2 - 3 - 2 - 3 3 - 1 - 3 - 2 4 5 - 2 - 5 - 4 6 - 2 - 6 - 20 7 - 5 - 7 - 7 EPSON MALE PLUG 1. 5. 6. 2. 4. 3. 9 PIN FEMALE - 25 PIN MALE SERIAL PLUG FOR HP PLOTTER TO PC -------------------------------------------------------------- 1 ------ 4 2 ------ 2 3 ------ 3 4 ------ 5,6 5 ------ 7 6,8 ------ 20 7 ------ 8