I am trying to set up a closed loop control system to synchronize the speed of 2 different sized rollers. The large roller is driven by the Product "web" and would be my master. The smaller roller is driven by an AC motor controlled by a Powerflex 4 VFD. The small roller needs to match the speed of the product (surface speed of the large roll) as it applies a painted pattern on the web. Too fast or too slow and the painted image will smear. I am not a controls engineer so I need a little help. I am wondering if I can get my 0-10VDC analog speed signal for the drive from a tach generator that rides on the master roll and use feedback from a similar tach on the smaller slave roll? I am sure these signals will have to go through a comparator of some sort to make the speed correction. What components are required for this?