PRB: Accessing WINMODEM with MSComm Control Can Hang Application

MORE INFORMATION

Steps to Work Around Behavior

1. Create a new Standard EXE project. Form1 is created by default.
2. Choose Components from the Project menu, check the "Microsoft Comm Control," and click OK.
3. Add an MSComm control to the form.
4. Add the following code to Form1's code window:

         Private Sub Form_Load()
   
            With MSComm1
               .Handshaking = 2 - comRTS
               .RThreshold = 1
               .RTSEnable = True
               .Settings = "9600,n,8,1"
               .SThreshold = 1
               ' Leave all other settings as default values.
            End With
            ' These next 2 lines avoid the problem
            MSComm1.PortOpen = True
            MSComm1.Output = "AT"
         End Sub
   
   						

5. Run the program. Without the MSComm1.Output line, the application will consume resources and may hang. With this line, the application runs fine, as expected.