title: Access to the port 'COM4' is denied
body: <p>I am using arduino (some micro-controller), and I made an ASP.net page to communicate with it. I connected arduino to serial-port COM4. When I run the ASP.net website, I get the following error:</p>
  
  <p>Exception Details: System.UnauthorizedAccessException: Access to the port 'COM4' is denied. </p>
  
  <p>ASP.NET is not authorized to access the requested resource. Consider granting access rights to the resource to the ASP.NET request identity. ASP.NET has a base process identity (typically {MACHINE}\ASPNET on IIS 5 or Network Service on IIS 6 and IIS 7, and the configured application pool identity on IIS 7.5) that is used if the application is not impersonating. If the application is impersonating via , the identity will be the anonymous user (typically IUSR_MACHINENAME) or the authenticated request user. </p>
  
  <p>To grant ASP.NET access to a file, right-click the file in Explorer, choose "Properties" and select the Security tab. Click "Add" to add the appropriate user or group. Highlight the ASP.NET account, and check the boxes for the desired access.</p>
  
  <p>now i know it may sound like the solution is right there: " to grant asp.net access to..." but i don't know what file they are talking about!
  So please can anybody point out the solution ?
  PS: I first did a windows form application and it worked. So there is nothing else using the COM4.</p>
  
  <p>Thanks in advance.</p>