Interconnection of 2 DB-25 connectors as a null-modem cable.

7 GND	--	7 GND

2 TxD	--	3 RxD

3 RxD	--	2 TxD

4 RTS	--	5 CTS

5 CTS	--	4 RTS

6 DSR	\_	20 DTR
8 CD	/

20 DTR	_/	6 DSR

	 \	8 CD

Interconnection of 2 DB-9 connectors as a null-modem cable.

5 GND	--	5 GND

2 TxD	--	3 RxD

3 RxD	--	2 TxD

7 RTS	--	8 CTS

8 CTS	--	7 RTS

6 DSR	\_	4 DTR
1 CD	/

4 DTR	_/	6 DSR

	 \	1 CD

There's also a complete pinout of the PC's communication ports available. [an error occurred while processing the directive]