Serial Port Communication in MFC

[QuickDeveloper]

Hi I Wrote a program to Communicate with a Serial Port in MFC.The problem is if i use WriteFile and ReadFile immediately i get the correct data.But if i Start a thread and use WaitCommEvent then the Program gets stuck up in WriteFile. I hav filled the DCB structure too. what could be the problem with WriteFile?? PS:I am not using Overlapped I/O Any Links Would do Fine.

"Every morning I go through Forbes list of 40 richest people in the world. If my name is not in there, I go to work..!!!"

[CPallini]

I think you have to post the relevant code. :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.

[Roger Stoltz]

QuickDeveloper wrote:

if i Start a thread and use WaitCommEvent then the Program gets stuck up in WriteFile.....I am not using Overlapped I/O

If you're not using overlapped I/O, you can only issue one request at any given time to the driver. If you issue another it will block waiting for the previously issued request, which is exactly what happens in your case: ::WaitCommEvent() is waiting for something to happen before returning while blocking the ::WriteFile() call. If you're writing an application that is supposed to issue both read and write requests, you should only consider the overlapped alternative. Have a look at an example on overlapped I/O here[^].

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[QuickDeveloper]

Thanks Roger ...i am using Overlapped I/O and it's Working Fine.

"Every morning I go through Forbes list of 40 richest people in the world. If my name is not in there, I go to work..!!!"