Rafal is right. Which Pin on which Display do you want to use and what kind of signal do you have from your rotary encoder?
My excample works, if you connect it to a MF input and create a toggling signal with a compare component (e.g. "your" 0 line is at 0.5V, just compare the voltage input with 500(mV) and connect it to my "frq_in".
@Rafal:
Your calculation is excatly, what I did in my excample, just using the diameter instead of the radius and multiplying with 314 instead of pi because of the extraordinaly good floating point performance of Plus1