[DonRotolo]

Ah. OK.
You are seeing the pot value change, right? If so...
Then you multiply it by 100. So 1 volt = 100, 2 volts = 200... Remember the max range ofr a Victor for example is 0 to 254 - do you see a scaling issue here?

OK. Find the minimum value of your pot (say it is zero) and the maximum value (say it is 5.1). Then find the min and max valuse you can send to the Victor or Jaguar (say it is 0 and 254) (NOTE: Your values may be different, deoends on how you do it)

Then 0 = 0, and 5.1 = 254. Multiply the pot by (254/5.1 = 49.8 and it should be OK.

This assumes that you can control the speed of the motor manually - that is, set the output to 200 and it goes one speed, and 230 it goes another speed. That has to be working!