Comtrol Multiport Modems Windows 98 - Manual (Page 51)

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Opening Ports Higher Than COM10
Opening Ports Higher Than COM10
To open up COM ports higher than COM10 a special named format is used with
CreateFile(): \\.\COM10 (when using the C language you need to double up the
backslashes: \\\\.\\COM10. This works only for 32-bit programs running under
Windows NT, 98/SE, or ME. 16-bit applications running under Windows NT, 98/
SE or ME also have this restriction.
COMMTIMEOUTS : GetCommTimeouts() and SetCommTimeouts() Structure
These features are implemented in a standard part of the operating system and
not in the port-driver, although it does rely on callback facilities built into the
driver. These timeouts should be used to avoid getting stuck forever in a read or
write operation when using the standard (non-overlapped) mode of operation.