And I'm not using PWM to +/- speed. I am using roboteq Ax500 motor driver communicating over the RS232 serial port. In order to increase or decrease speed, it understands a formated string of characters such as "!a3F".
where !a stands for left wheel forward and the next two characters are hex.(00 > 0% Speed and 7F stands for 100% speed).
How do I increase the number from 00 --> 7F until the optical encoder records 100ticks, then it stops speed increment.