OBDII vehicle speed acquisition

I am working on a small project that doesn't seem to be so simple anymore.

I have a data acquisition (USB-1408FS) unit hooked up to a laptop.
I would like to record vehicle speed from the OBDII port, and input it into the data acq.

The vehicle is a 2005 Ford truck.

What is the most efficient way of doing this? There has to be a way, but I can not seem to find a simple way.

Thanks in advance for your reply.
Steve

Depends on what you are connecting to the OBDII with

here is a VB6 class for the ELM

http://www.mp3car.com/vbulletin/engi...vb6-class.html

Not entirely sure what you mean by "inputting it into the data acq", but your best bet for reading speed would be to buy an OBD2 tool, such as those sold by http://www.obdpros.com/(This is an ELM unit, which is compatable with all programs supporting the ELM327 and most programs supporting the ELM323) , and connecting via serial (or via a program), and as you can see from http://en.wikipedia.org/wiki/OBD-II_PIDs that list, 010D is the command to send to retrieve vehicle speed.

I have an existing data acq unit that I am trying to feed vehicle speed into. The data acq measures a voltage, that is it. I could use one of the many existing components and input vehicle speed into the laptop, however I was initially trying to input the information into the data acq module I already have, even if it would be slightly more work.

Basicly here is my ideal setup even though it is not efficient.

OBDII port > Cable > Module that sends command to OBDII and recieves speed data, then outputs the data as a voltage > Cable > Data Acq > Cable > Laptop running software I already have.

I don't know if this can be done easily or not.
Thanks,
Steve