Using write function of Data Acquisition Toolbox won't generate a continuous wave.

Hello everyone, I'm trying to build a GUI in matlab that enables me to read a signal from an input channel of my DAQ device (Rogadaq2) which I managed to do already. Additionally, I'm trying to write a desired sin wave to the output channel using the "write" function, however, the signal written is not really continuous. This is a big problem, especially because I need to compute the FFT of this signal. The figure with the signal should corresponde to a a sine wave with Amplitude = 1 and Frequency = 10Hz. I am quite new to this toolbox and haven't found usefull information in the package's documentation. I would appreciate if anyone knows what is causing this and how I can make it a perfect continuous sine wave. Thanks in advance!

function GeneratingStartButtonPushed(app, event)
            % Disable DAQ device, channel properties, and start acquisition UI components
            setAppViewState(app, 'Outputacquisition');    
             
            t = linspace(0,1,app.DAQoutput.Rate);
            frequency = app.GeneratingSignalFrequency.Value;
            Amplitude = app.GeneratingSignalAmplitude.Value;
            output = Amplitude*sin(2*pi*frequency*t); 
            
            try
                %Create and start DAQouput object
                start(app.DAQoutput,"RepeatOutput")
%                     write(app.DAQoutput, [output' ;  ones(1*size(output))']); 
                      write(app.DAQoutput, [ones(1*size(output))' ;  output']);
            catch exception
                % In case of error show it and revert the change
                uialert(app.LiveDataAcquisitionUIFigure, exception.message, 'Start error');   
                setAppViewState(app, 'OutputConfiguration'); 
            end
            % Clear Log status text
            app.LogStatusText.Text = '';app.AcquiringStartButton
            plot(app.LiveAxes_2, t, output); 
        end

[chrisw23]

try the "Continuous" option instead of "RepeatOut"

[Mario Malic]

I will be posting an app that does some of the stuff you mentioned soon, and it's preety neat.

Try also preload.

Check Rate property of https://uk.mathworks.com/help/daq/daq.interfaces.dataacquisition.html object, maybe it has something to do with it, as the Rate is set to be minimum when you initialize the object.

[Ivo Bastos]

@Mario Malic Thank you so much! Actually preloading solved my problem. I'm looking forward to seeing that app, best of luck working on that

[Mario Malic]

I have posted my app here, unfortunately it is not yet applicable for the output, but it shouldn't be an issue to add that functionality. https://uk.mathworks.com/matlabcentral/fileexchange/128118-daqx

Answer 1

[Vanshika Vaishnav]

Preloading the function solves the problem.

Also check Rate property of https://uk.mathworks.com/help/daq/daq.interfaces.dataacquisition.html object, as the Rate is set to be minimum when the object is initialised.