Asynchronously writing and callback function

hi everybody,
i am working on an asynchronous write operation as described in
'Asynchronously Reading and Writing with the NI-DAQmx Visual C++ Class Library'
in the Visual Studio .NET documentation.
I've worked with asynchronous read functions and callbacks (the OnEvent function in this example) before, and it worked
well.
Atm i am doing output to 16 digital outputs on my PCI6259 card. I want to output a waveform stored in a vector containing about 1000 samples.
So i installed the event handler for my writer object, and started the output by calling
'WriteMultiSamplePortAsync'.
The problem is, that the callback function 'OnEvent' is called after the first sample of my vector is sent, and not after the complete vector.
i need to know when my whole buffer is through, because i have to recalculate it and send it again...
Anyone has an idea where the problem is?
Thx in advance
markus

Well i've attached a somehow simplified code of my problem.
First i start two tasks, one counter, which acts as sample clock for my digital output, and the digital output task itself.
In this example i use a output frequency of 100kHz.
Then an event handler for my digital write operation is installed.
Next, i create a vector with size 1000, fill it with some data and write it out calling 'WriteMultiSamplePortAsync'
What i would expect now, is that the OnEvent-function is called, as soon as all of the 1000 samples of my output vector have been sent.
But what really happens is that OnEvent is called after the first of the 1000 samples has been written.
As i said before, the same procedure works fine with analog input tasks.
Regards
Markus
Attachments:
AsyncDigitalOut.cpp ‏3 KB

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Hello hemm,
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Maybe you could add some Message Tags so that people that are following specific tags might be able to detect your question and help you.
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If this is the case then it might be interesting to note that many of the Arduino users over here are using the NI LabVIEW Interface for Arduino Toolkit:
http://sine.ni.com/nips/cds/view/p/lang/en/nid/212478
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Thierry C - Applications Engineering Specialist Northern European Region - National Instruments
CLD, CTA
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Asynchronously writing and callback function

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