Do-More Calculate Velocity from Distance Sensor HELP

I'm using a Do-More and a Leuze Electronic ODSL 9 sensor to monitor a large hydraulic cylinder. I have to calculate and log the velocity. I have tried to capture a reading based on a 50ms or 100 ms clock the move that to a R location then capture a second and move to another R location then do the math between the two and do the calculation. I cant get it to work. Does anyone have a suggestion on how to get there. The fastest the cylinder could be moving is 17'/sec. The stroke is 5'.

Can you post what you have so far?
The moves must be done with an One-Shot Contact.

Regards,