c#串口打开报错System.IO.IOException: 函数不正确

Question

1，第一次打开串口报错：System.UnauthorizedAccessException: Access to the port 'COM1' is denied.
2，然后通过设备管理器，禁用串口，在启动串口后
3再次打开串口，报错，System.IO.IOException: 函数不正确。

at System.IO.Ports.InternalResources.WinIOError(Int32 errorCode, String str)
at System.IO.Ports.InternalResources.WinIOError()
at System.IO.Ports.SerialStream.SetBufferSizes(Int32 readBufferSize, Int32 writeBufferSize)
at System.IO.Ports.SerialPort.Open()

Answer 1

http://blog.csdn.net/jimfire/article/details/41598201