Getting current time on x-axis using Design app - GUI

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Teresa Carneiro 2021-7-2

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/870573-getting-current-time-on-x-axis-using-design-app-gui

编辑： Teresa Carneiro 2021-7-9

Hello! I'm trying to use GUI app to plot real-time data and I can only get the x-axis to show the elapsed time in seconds, but I would like to get the current clock time, like 13:48:17. I've tried a few things but nothing seems to work, I would really appreciate your help. Also I would like the plot to update every 1sec rather than constantly, but don't know if that is defined on the hGui function or on the dataCapture function.

I'm using the code in this page https://www.mathworks.com/help/daq/software-analog-triggered-data-capture.html, and I think I've got to edit the hGui function somewhere in this part:

hGui.Axes1 = gca;
hGui.LivePlot = plot(0, zeros(1, numel(s.Channels)));
xlabel('Time (s)');
ylabel('Voltage (V)');
title('Continuous data');
legend({s.Channels.ID}, 'Location', 'northwestoutside')
hGui.Axes1.Units = 'Pixels';
hGui.Axes1.Position = [207 391 488 196];
% Turn off axes toolbar and data tips for live plot axes
hGui.Axes1.Toolbar.Visible = 'off';
disableDefaultInteractivity(hGui.Axes1);

This is how I'm acquiring data:

[eventData, eventTimestamps] = read(src, src.ScansAvailableFcnCount,'OutputFormat', 'Matrix');

If I could change evenTimestamps to the current time in the format 'HH:MM:SS', I think that would do it, because in the matrix instead of the miliseconds I would be getting the current time.

Or maybe I've got to edit the dataCapture function in this part:

% Update x-axis limits
xlim(hGui.Axes1, [dataBuffer(firstPoint,1), dataBuffer(end,1)]);
% Live plot has one line for each acquisition channel
for ii = 1:numel(hGui.LivePlot)
    set(hGui.LivePlot(ii), 'XData', dataBuffer(firstPoint:end, 1), ...
                           'YData', dataBuffer(firstPoint:end, 1+ii))
end

It may not have anything to do with editing either of this code parts so I would really like someones help :)

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Geoff Hayes 2021-7-2

Teresa - so you want to show the current time along the x-axis? Where is the time data that corresponds to the buffered data?

Teresa Carneiro 2021-7-5

I don't know what that means

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采纳的回答

Cris LaPierre 2021-7-2

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在 MATLAB Online 中打开

The same way you would do it in MATLAB. If your duration corresponds to daytime, then you can just set the format of your xdata using xtickformat.

x=seconds(4800:50:5900);

y = rand(size(x));

plot(x,y)

xtickformat('hh:mm:ss')

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Teresa Carneiro 2021-7-6

在 MATLAB Online 中打开

What do you mean "how does your elapsed time compare to time-of-day?" I need it to show me the current time every second. This was my code using just matlab, maybe it can make you understand what I want a little better, and I didn't need to make any calculations on this code, it just showed me the current time I started recording data:

clear
close all
time = 0;
data = 0;
% Set up the plot
figure(1)
plotGraph = plot(time,data,'-r' ); 
title('DAQ data log','FontSize',15);
xlabel ('Elapsed Time (s)','FontSize',10)
ylabel('Voltage (V)','FontSize',10);
h = animatedline;
ax = gca;
ax.YGrid = 'on';
ax.XGrid = 'on';
% Set up the data acquisition
dq = daq("ni");
ch1 = addinput(dq, "Dev1", "ai0", "Voltage");
dq.Rate = 1000;
% Start the data acquisition
start(dq, "Duration", seconds(20))
n = ceil(dq.Rate/10);
% Open the text file
data = read(dq, n);
writetimetable(data,'data.txt','Delimiter','bar');
type 'data.txt';
while ishandle(plotGraph)
    data = read(dq, n)
    writetimetable(data,'data.txt','Delimiter','bar','WriteMode','append');
    type 'data.txt';
    voltage1 = data.Dev1_ai0;
    
    t = datetime('now');
    
    for i = 1:100
    % Add points to animated line
        if isvalid(h)
        addpoints(h, datenum(t), voltage1(i))
        end
    end
    % Update axes
    ax.XLim = datenum([t-seconds(15) t]);
    datetick('x','keeplimits')
    drawnow
end
disp('Plot Closed')

And I don't know where I should insert this code you just gave me. In the function where I acquire the data or in the function that creates the GUI? Sorry for the trouble but I'm very new in matlab

Cris LaPierre 2021-7-7

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I'm not sure your code is doing what you want. For example, I think the for loop in this code will plot all 100 points at the same x location, so it will look like a vertical line rather than a continous stream of data.

while ...
...
t = datetime('now');
    
for i = 1:100
% Add points to animated line
    if isvalid(h)
    addpoints(h, datenum(t), voltage1(i))
    end
end
...
end

In app designer, I would likely make an approach similar to what you have done. Perhaps with the following changes.

hGui.LivePlot = plot(hGui.Axes1, 0, seconds(zeros(1, numel(s.Channels))));
xlabel('Time (s)');
ylabel('Voltage (V)');
title('Continuous data');
xtickformat('hh:mm:ss')
legend({s.Channels.ID}, 'Location', 'northwestoutside')
hGui.Axes1.Units = 'Pixels';
hGui.Axes1.Position = [207 391 488 196];
% Turn off axes toolbar and data tips for live plot axes
hGui.Axes1.Toolbar.Visible = 'off';
disableDefaultInteractivity(hGui.Axes1);
...
% Update x-axis limits
xlim(hGui.Axes1, [dataBuffer(firstPoint,1), dataBuffer(end,1)]);
% Live plot has one line for each acquisition channel
for ii = 1:numel(s.Channels)
    hGui.LivePlot(ii).XData = dataBuffer(firstPoint:end, 1);
    hGui.LivePlot(ii).YData = dataBuffer(firstPoint:end, 1+ii));
    drawnow
end

Note that this approach will add the entire buffer of data to the plot all at once. If you want to add it point by point, you will need to add another loop.

for r = firstPoint:size(dataBuffer,1)
    for ii = 1:numel(s.Channels)
        hGui.LivePlot(ii).XData = dataBuffer(r, 1);
        hGui.LivePlot(ii).YData = dataBuffer(r, 1+ii));
    end
    drawnow
end

Cris LaPierre 2021-7-8

在 MATLAB Online 中打开

Not perfect, but this works for what I was trying to create. You will likely have to modify to get it to do exactly what you want.

Main changes:

1. in createDataCaptureUI, create the plot using a time for your x value instead of 0. I used datetime("now"). You'll want to add this value to hGui so it is available to adjust your time data in dataCapture. This is where you set xtickformat as well. Here is just the subset with all 3 changes.

...
hGui.t0 = datetime("now");
% Create the continuous data plot axes with legend
% (one line per acquisition channel)
hGui.Axes1 = axes;
hGui.LivePlot = plot(hGui.t0, zeros(1, numel(s.Channels)));
xlabel('Time (s)');
ylabel('Voltage (V)');
title('Continuous data');
xtickformat('HH:mm:ss');
...

2. In dataCapture, I've assumed your XData is elapsed time in seconds. To make it day time, I need to convert the first column of dataBuffer to seconds and add hGui.t0 to it. The xlim command is setting what data is displayed. I don't know what you want, so I set it to just show the new data. You can modify this to meet your requirements.

...
% Update x-axis limits
xlim(hGui.Axes1, hGui.t0 + seconds(dataBuffer([firstPoint end], 1)'));
% Live plot has one line for each acquisition channel
for ii = 1:numel(hGui.LivePlot)
    hGui.LivePlot(ii).XData =  hGui.t0 + seconds(dataBuffer(firstPoint:end, 1));
    hGui.LivePlot(ii).YData = dataBuffer(firstPoint:end, 1+ii);
end
...