I am trying to display the speed of my car on a computer screen.

I have installed a sensor on the wheel axle that gives 6 pulses per
revolution of the shaft (14" inches per pulse.)

The DI-194RS can count these pulses.

Counting the pulses produced in 500 milliseconds does not give me
enough resolution or accuracy at slow speeds, so I thought I could
instead measure the time period between 2 pulses and then calculate
the speed.

I am having trouble doing this in Visual Basic. I have been using
UltimaSerial.TransitionCounter(0, Low2High)

Can anyone suggest which of the UltimaSerial "properties" I should
use and / or suggest how to best do this?

Thank you in advance.

Dave