continuous analog acquisition with DAQmxBaseReadAnalogF64 reads only 2 values in buffer

[elisabeth]

I want to continuously acquire an analog signal, to process it real time.

I therefore use the code given in the example /usr/local/natinst/nidaqmxbase/examples/ai, but change the DAQmxBaseReadAnalogF64

pointsToRead to -1 so that I get all the signal up to the current time :

DAQmxBaseReadAnalogF64(taskHandle,-1,timeout,DAQmx_Val_GroupByScanNumber,data,bufferSize,&pointsRead,NULL));

I tried to increase the buffer size, reduce the frequency, whatever I do, there is always only 2 points acquired in the buffer.

Any idea where the problem comes from ?

Thanks a lot for your help,

Elisabeth

[Marc L.]

the forum has been posted twice :

http://forums.ni.com/ni/board/message?board.id=250&message.id=18205

Marc L.

NIF