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HOWTO: Specify Serial Ports Larger than COM9
Article ID: 115831 - View products that this article applies to.
This article was previously published under Q115831
CreateFile() can be used to get a handle to a serial port. The "Win32 Programmer's Reference" entry for "CreateFile()" mentions that the share mode must be 0, the create parameter must be OPEN_EXISTING, and the template must be NULL.
CreateFile() is successful when you use "COM1" through "COM9" for the name of the file; however, the message
is returned if you use "COM10" or greater.
If the name of the port is \\.\COM10, the correct way to specify the serial port in a call to CreateFile() is as follows:
NOTES: This syntax also works for ports COM1 through COM9. Certain boards will let you choose the port names yourself. This syntax works for those names as well.
CreateFile( "\\\\.\\COM10", // address of name of the communications device fdwAccess, // access (read-write) mode 0, // share mode NULL, // address of security descriptor OPEN_EXISTING, // how to create 0, // file attributes NULL // handle of file with attributes to copy );
Article ID: 115831 - Last Review: March 1, 2005 - Revision: 3.3