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Support Forum » Serial or null-modem

May 08, 2009
by brian
brian's Avatar

I'm trying to connect my USB Nerdkit directly to a serial port on a computer without using the USB-Serial adapter. Will I need a null-modem cable or a straight-through cable?

May 19, 2009
by mrobbins
(NerdKits Staff)

mrobbins's Avatar

Hi Brian,

You'll want to use a straight-through cable, and make sure it's really an extension cable -- male on one end and female on the other. A null-modem cable is used when you're connecting two computers back-to-back, and it switches the Transmit (TD) and Receive (RD) wires, so that the TD of one connects to the RD of the other, and vice versa. This is not needed here -- our serial setup already has the correct TD/RD sense as-is.


May 23, 2009
by brian
brian's Avatar

Thanks. I have a regular pass-through serial cable. I tested continuity between pins on each side with a multimeter before using.

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