Analog discovery 2 continuous data acquisition

[Ting]

Hello all!

I am doing a university project which needs to use AD2 to do continuous data aquisition on analog signals. I need 12.8 kHz sampling frequency to record about 10 seconds data.

This project is implemented on labview. I found the existing libraries ('Digilent WF VIs' and 'AD2 toolkit') seem not having the continuous DAQ feature. I would like to ask, how I can set AD2 to continuous acquisition mode (acqmodeRecord) of in labview.

Any help would be appreciated! Thanks!

 

 

 

 

[attila]

Hi @Ting

See the following: Digilent_WaveForms_Stimulus Response (MSO and FGEN)_001.vi

The sample argument should be "pointer to value" and I have also rewired error path.

[attila]

Hi @Ting

The Digilent WF VIs with newer WF version will perform record if the number of samples (time x rate) is higher than the device buffer size.
https://forum.digilentinc.com/topic/8908-waveforms-beta-download/

In MSO Read.vi make sure the allocated analog and/or digital data size suffice, adjust these to be at least the required number of samples.
Like here 200000 is suffice for 128000 (12.8kHz x 10)

 

[Ting]

Hello Attila,

Thanks for your information!

I am also wondering if immediate sampled data outputs are available in the labview vi? 

[attila]

Hi @Ting

No but you can use the FDwfAnalogInStatusSample C function after calling the FDwfAnalogInStatus or MSO QueryAcquisitionStatus.vi
For the function hdwf argument the VI instrument handle can be used.

[Ting]

Hello attila,

I added the 2 C functions in the Labview vi,  but I cannot read data from FDwfAnalogInStatusSample. 
Could you take a look please? Thanks!

 

Digilent_WaveForms_Stimulus Response (MSO and FGEN)_001.vi

[Ting]

Hello @attila

Thanks for your help！
When I record the output of 'pdVoltSample', sample lost will happen.
The picture  is a 1Hz signal I recorded with this program, and the sample lost exceeds 50%.
I would like to ask, how I can get the immdiate sample output without sample lost?

Thanks!

 

Digilent_WaveForms_Stimulus Response (MSO and FGEN)_010.vi

[attila]

Hi @Ting

The FDwfAnalogInStatus/Sample can be used to retrieve one sample for each channel.
The MSO Read.vi can be used to capture up to device buffer size (AD 8k) of samples at up to 100MHz or to record more samples at lower rate, up to about 1MHz.

[Ting]

Hi attila,

So I can't retrieve multiple samples output on Labview like C and Python?

In my project, AD2 is used to collect samples of a reference signal for phase locked loop. If it is possible, I hope AD2 can read immediate data output without losing samples.
In this case, I can directly do phase locked loop and measurement in real time.

Is there a way I can do it? Thanks!