I am building what equates to a two axis CNC machine (x and z). The x-axis is a rack and pinion setup using Ahren's parts. The z-axis is a metal cable that is wound by a servo to place constant torque on a rover below.

We are trying to get the carriage to follow the rover below using a potentiometer attached to the cable to detect when it breaks 90 degrees. I am thinking that this would just be set up as one axis of a joystick controlling the jog function in EMC2, but I'm concerned about the stepper chattering back and forth trying to get it perfect. So I have 2 questions: What is the simplest way to get the potentiometer data to EMC2? Is there any PID control for jogging in EMC2?

~Will