

as someone else already mentioned, don't "carry thru" the other 23 pins.

plan A, minimal null modem:
	SG(7)   -  SG(7)
	TD(2)   -  RD(3)
	RD(3)   -  TD(2)
if you're transfering files betwen 2 PCs, this ought to work (unless
you have a persnickity comm program).

plan B, null modem with modem control:
	SG(7)   -  SG(7)
	TD(2)   -  RD(3)
	RD(3)   -  TD(2)
	DCD(8)  -  DTR(20)
	DTR(20) -  DCD(8)
some comm software will wait for DCD before transferring anything.
such software will raise DTR to enable the modem to accept a call.
with this cable, each side's DTR will drive the other's DCD.

plan C, null modem with hardware flow control:
	SG(7)   -  SG(7)
	TD(2)   -  RD(3)
	RD(3)   -  TD(2)
	RTS(4)  -  CTS(5)
	CTS(5)  -  RTS(4)
for high-speed transfers, you want the flow control.

plan D, deluxe null modem (combine B and C):
	SG(7)   -  SG(7)
	TD(2)   -  RD(3)
	RD(3)   -  TD(2)
	RTS(4)  -  CTS(5)
	CTS(5)  -  RTS(4)
	DCD(8)  -  DTR(20)
	DTR(20) -  DCD(8)
this one is ideal.  it leaves out DSR and RI (rarely used anymore).
if you're really paranoid, or you just have an 8th wire to spend,
you might add:
	FG(1)   -  FG(1)

the pin numbers above are (obviously) for 25-pin connectors.
i don't have a 9-pin pinout handy.
