Jan,

Thanks for that link. I have read up on this info before I posted and believe that I understand what you are saying, but I am seeing my output stay at a constant "1", regardless of what my external input is doing.

I have a motion detector connected to my input. It is a NC output, so no motion it ouputs 0V to my input. When it seeing motion I get 5v on my input, for about 2.5 sec. When I reset my device, I see 0V on the input after it dectects motion for the first time the input stays at a "1" regardless if there is 0V or 5V on the input. Below is my code and circuit diagram. I hope this clears up any questions.

void read_din1 (void)
{

   DIGITAL_IN1 = 1;
   delay_10ms();

   return DIGITAL_IN1;

}