Line 13 attempts to construct a QextSerialPort with a port of "" because at line 12 the combo box will possibly have no meaningful value. You haven't given the user a chance to enter anything in that widget yet. I expect that the port is not open after this but, even if it were, you will close it at line 24.
Once you get past opening the port you should reconsider using a polling mechanism and use the readyRead() signal to trigger handling when data is available.
Last edited by ChrisW67; 27th May 2011 at 09:38.
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