DAQ ANSI C callback function

[Minal]

I am trying to read data from NIhardware using NIdaqmx.h & lib files.

Code is in Vc++2005 .

I am able to read data when it is configured for Finite samples, but when configured for continuos ,call back function is not getting called.

I am using "C:\Program Files\National Instruments\NI-DAQ\Examples\DAQmx ANSI C\Analog In\Measure Voltage\Cont Acq-Int Clk" example.

Output of DAQmxRegisterEveryNSamplesEvent function is zero which indicates success.

I have breakpoint in call back function & after registering call back function my program is not going to that breakpoint.

Callback is registered as DAQmxRegisterEveryNSamplesEvent(taskHandle,DAQmx_Val_Acquired_Into_Buffer,1000,0,EveryNCallback,NULL);

Please if some one can help me solving this problem.

Regards,

Minal

[Elizabeth W]

Hi Minal,

Do you get any sort of error message?  Or does DAQmx just never return any samples but also never give an error code?

You could try creating a simulated device and see if the same problem occurs with the simulated device.  What device are you using?

Also, one other question for you -- have you modified the example code at all or is it just the original example?

[PSchlup]

Dear Minal,

I experienced a similar issue using C++ VisualStudio .NET: The callback function registered by DAQmxRegisterEveryNSamplesEvent was only called when the sampleMode parameter in DAQmxCfgSampClkTiming was set to DAQmx_Val_FiniteSamps, but not for DAQmx_Val_ContSamps.

I eventually tracked the issue down to the sampsPerChanToAcquire parameter in DAQmxCfgSampClkTiming: The callback is only called for values below 10000.

Since you have sampsPerChanToAcquire = 1000 in your code, this may not be relevant to your problem, but I recommend starting from National Instruments' ContAcq-IntClk.c example and changing parameters one at a time to find the issue.

Good luck!
Philip

[Minal]

Hey thanks guys.

By upgrading the version to DAQ8.5 my problem was solved.

Minal