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I have an 8 port serial communications card in a WindowsNT system installed as COM3, COM4, ... COM10. I can use any of the eight ports using the WindowsNT hyperterminal utility



I am using Visual C++ 6.0 with MFC and attempting to open different ports with the following statement



m_commhandle = CreateFile((LPCTSTR)m_port, GENERIC_READ|GENERIC_WRITE,0, NULL, OPEN_EXISTING, 0,NULL)



This statement works for all of the ports EXCEPT COM10. GetLastError() returns a 2 (ERROR_FILE_NOT_FOUND). In DEBUG, m_port contains "COM10", but the CreateFile(...) still fails. Hyperterminal is not running when I a making these tests, but when I am not debugging my code, and hyperterminal is loaded, it has no problem opening and communicating over COM10, too



Is this a BUG in VC++C6.0


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"TLNA" <anonymous@discussions.microsoft.com>wrote in message

the WindowsNT hyperterminal utility.

the CreateFile(...) still fails. Hyperterminal is not running when I a

making these tests, but when I am not debugging my code, and hyperterminal

is loaded, it has no problem opening and communicating over COM10, too!

TLNA,



The string should be "COM10:" not "COM10".





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"COM10:" fails with a GetLastError() of 123 (ERROR_INVALID_NAME

"COM10" still fails with a GetLastError() of 2 (ERROR_FILE_NOT_FOUND



For reference

"COM6" succeeds in opening and running properl

"COM6:" also succeeds in opening and running properly

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No it shouldn't!



To access COM ports past 9 you must specify the name like this \\.\COM10,

which becomes "\\\\.\\COM10" when specified in C++. This works for COM 1 to

9 as well, so there is no need to special case it.



Best Regards

Julian N.



"Trevor" <trevor@nospam.com>wrote in message



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Hi,

MSDN says in article Q115831 how to specify COM ports larger than 10.



Use this format in your CreateFile:

CreateFile("\\\\.\\COM10",fdwAccess...

This also works for COM ports 0 to 9.



HTH,

Wolfgang



"TLNA" <anonymous@discussions.microsoft.com>schrieb im Newsbeitrag



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Julian,

Your suggestion works! Fantastic

Thank you very much

Tom

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Wolfgang

Thank you for the information. It solved my problem! Also, thank you for the MSDN article number

Regards

Tom

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