"P"s will most likely be the easiest for you. The difference is really simple. The "D" model uses a 0-10v analog input. The "P" model uses a pwm input. Converting pwm to analog isn't really easy (it's not impossible), so the "D" model isn't that helpful when building your own controller. Just keep in mind that you need to supply the driver 10v, not the 5v that the Arduino outputs. You will need to use something like a FET to do the switching duties between the Arduino and a 10v regulated source.