title: How can send and receive +5 volt through usb port D+ and D- pin
body: <p>I have made an image comparing software. which start processing after clicking on a button.
  But I want to get 5 volt signal from usb port using white(D-) and green(D+) pins for a millisecond and want to receive this signal in my c# code for initiating the process.</p>
  
  <p>if image found difference then i want to send back a 5 volt signal to switch on an alarm.
  is it better to send back a signal by using RS232 Pin no. 4?</p>
  
  <p>by using</p>
  
  <p>serialPort.DtrEnable = true;</p>
  
  <p>Any idea please?????</p>