RS232 Serial Communications Cables

Here are some typical cable diagrams used in serial communications.

XON/XOFF 25 - 25

25 Way 25 Way
TX 2 ---------> 3 RX
RX 3 <--------- 2 TX
SG 7 ---------- 7 SG

XON/XOFF 25 - 9

25 Way 9 Way
TX 2 ---------> 2 RX
RX 3 <--------- 3 TX
SG 7 ---------- 5 SG

XON/XOFF 9 - 9

9 Way 9 Way
TX 3 ---------> 2 RX
RX 2 <--------- 3 TX
SG 5 ---------- 5 SG

Full Hardware Handshaking 25 - 25

25 Way 25 Way
TX 2 ---------> 3 RX
RX 3 <--------- 2 TX
RTS 4 ---------> 5 CTS
CTS 5 <--------- 4 RTS
DSR 6 <---O----- 20 DTR
DCD 8 <--/
SG 7 ---------- 7 SG
DTR 20 -----O---> 6 DSR
\--> 8 DCD

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