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Getting Error 57 when opening COM port on XP system RRS feed

  • Question

  • I have a VB .Net 2005 application that attempts to open a COM port that is configured as a USB port.  During the open I get a "Error 57 occurred (in my open port routine) and was generated by System."  I also get the following message: "A device attached to the system is not functioning".  Device Manager shows a working USB port.  This problem can happen when my application is being started for the first time and the device that has the USB port is just powered on.  The problem can be reported during a close port operation as well as any time between the open and close.  Disconneting the USB cable and reconnecting restores the USB port but not everytime.  The problem is intermittent and can happen when running in the Visual Studio environment or not.  The USB device I am communicating with has a MicroChip 18F4550 processor with USB support.  The VB application is using the same COM port each time it  is run and the USB cable is not being accidently disconnected. Has anyone seen this type of problem before?
    Thursday, September 17, 2009 6:39 PM

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