 
 A Vernier Photogate should also be connnected to the second BTD 1 connector.
 The sketch monitors this photogate and Controls a stepper motor (unipolar or 
-bipolar) via a Vernier Digital Control Unit (DCU) connected to the second BTD 
+bipolar) via a Vernier Digital Control Unit (DCU) connected to the BTD 2 
 connector.
 
 This sketch will continuously check the photogate and start the stepper

    } ;//end of for
};// end of Step
 
void DCU (int output)
{
  switch (output) 
  {

int Direction =0;//direction 0 =CW
int x;
int StepValue;
const int Pin1 = 6;
const int Pin2 = 7;
const int Pin3 = 8;
const int Pin4 = 9;
int photogate =2; //This is the input for a photogate on the BTD 1 connector
int LEDpin =13;/// line for LED to turn on when photogate is blocked
int output; //number sent to DCU
