controlling 2 servos via usbserial

Other Hardware Robotics
4

I need to switch to an Arduino with a hardware serial port

Your Uno HAS a hardware serial port.

        strcpy(tempChars, receivedChars);
            // this temporary copy is necessary to protect the original data
            //   because strtok() used in parseData() replaces the commas with \0

But, you never use the original data, so it is NOT necessary to copy it. Save time; stop copying.

What, EXACTLY, are you sending to the Arduino?