Rotary encoder DRO. Inexpensive! fitted to RF30 Mill CNC,

#include <Wire.h> 
#include <LiquidCrystal_I2C.h>
#include <Encoder.h>// Encoder library.
Encoder myEnc(2,3);// Connected to Digital pins 2 and 3.
LiquidCrystal_I2C lcd(0x27,20,4);  

void setup() {
  lcd.init();                      // initialize the lcd 
  lcd.backlight();
  
}
long oldPosition = -999;


void loop()
 {
  const float Wv = (.1 * PI*.9848) / 600; // Math formula for 20 tooth pulley
                                    //and 600 pulse/revolution encoder.

  lcd.setCursor(7, 0); // (Column 7,ROW 0) (Column #0-19,Row #0-3
  lcd.print("Z Axis");
  lcd.setCursor(2, 1);
  lcd.print("inch");
  lcd.setCursor(14, 1);
  lcd.print("mm");
  lcd.setCursor(5, 2);
  lcd.print("Z Axis DRO");// Graphic symbols for a Z axis left and right travel.
  long newPosition = myEnc.read();
  if (newPosition != oldPosition)
  lcd.setCursor (0, 0);
  lcd.print (newPosition); // Display number of pulses, 1"~=1902.2 pulses.                       
  lcd.setCursor(2, 3);
  lcd.print(Wv * newPosition, 3);//Math formula * Encoder reading ,3 decimals
  lcd.setCursor(9, 1);
  lcd.print("|");// Graphic symbol to separate imperial and metric display.
  lcd.setCursor(9, 3);
  lcd.print("|");
  lcd.setCursor(11, 3);
  lcd.print(Wv * newPosition * 25.4, 2); // Formula to convert imperial
                                         // and metric, 2 decimals.
}