Cable to send DirectRT TTL signal to a BNC input

I'm trying to find a cable that can SEND a TTL signal from a computer running DirectRT to an external data acquisition system that take a voltage input (up to 10 mV) with a BNC connection (we do not need to receive any information in DirectRT - we're just marking when stimuli are presented to sync up behavioral and physiological responses). I can go out of my computer via either USB or a 9-pin serial connection, but this overall connection seems to be pretty odd because I haven't found anybody who stocks anything like it. Does anybody know of any retailers who have this type of cable? Any and all advice/comments would be appreciated. Thanks!

-David

That's a tricky one...

USB cables contain a high speed bus which wouldn't really work for you.

It would be possible, with some trickery, to get a regular signal out of your serial port. However, it would require an external adapter of some sort.

Can you confirm that your 10 mV value isn't really 10 volts?

Hi John,

10mV is the minimum input - sorry for the confusion. Does that make the problem any easier to solve?

There are tech specs for the other DAQ at [url]http://www.dataq.com/support/documentation/pdf/datasheets/720_730b.pdf[/url] (the lab I'm collaborating with on this project is using the DI-730).

David