C# Definition:

struct COMMTIMEOUTS {
   public TODO;
}

VB Definition:

Public Structure COMMTIMEOUTS
    Public ReadIntervalTimeout As Int32
    Public ReadTotalTimeoutMultiplier As Int32
    Public ReadTotalTimeoutConstant As Int32
    Public WriteTotalTimeoutMultiplier As Int32
    Public WriteTotalTimeoutConstant As Int32
End Structure

User-Defined Field Types:

None.

Notes:

If an application sets ReadIntervalTimeout and ReadTotalTimeoutMultiplier to MAXDWORD and sets ReadTotalTimeoutConstant to a value greater than zero and less than MAXDWORD, one of the following occurs when the ReadFile function is called:

->If there are any bytes in the input buffer, ReadFile returns immediately with the bytes in the buffer.

->If there are no bytes in the input buffer, ReadFile waits until a byte arrives and then returns immediately.

->If no bytes arrive within the time specified by ReadTotalTimeoutConstant, ReadFile times out.

http://msdn2.microsoft.com/en-us/library/aa363190.aspx