B4J Question com port busy error trapping

Sub btnopen_MouseClicked (EventData As MouseEvent)
    If btnopen.Text = "Open" Then
        sp.Open(cmbport.Value)
        sp.SetParams (BaudRate , DataBits , StopBits , Parity )
        sp.PurgePort(8)
        astream.Initialize(sp.GetInputStream, sp.GetOutputStream, "astream")      
        btnopen.text = "Close"
        lblstatus.Text = "Status: Connected"
    Else
        AStream_Terminated
    End If  
End Sub

Try
 sp.Open(...)
Catch
 Log("Error opening port: " & Exception)
 Return
End Try
...