Having issue in plotting live data of three channels in a single UI Axes

I am having issue in ploting real time data in UI Axes of 3 channels. I am able to plot the data of one channel but when i try for two or three channels it show an error or plots only one channel and the stops in between .Can anyone help me out where i am going wrong or at what thing i am missing to add in my code. The two values i wanna show are trip and alarm line which i want to fetch from app. Plz any one can guide me with the code.

i=1;

ii=1;

while strcmp(app.Switch.Value, 'On')

clear m

m = modbus('serialrtu','COM5',BaudRate=9600);

m.Timeout = 0.275;

% Rack 1 Slot 1 Module 1

serverId1 = 2;

tripM1A = read(m,"holdingregs",1,1,serverId1,"uint16");

alarmM1A = read(m,"holdingregs",6,1,serverId1,"uint16");

fullscaleM1A = read(m,"holdingregs",11,1,serverId1,"uint16");

processM1A = read(m,"holdingregs",44,1,serverId1,"uint16");

% Data of channels

app.ALARM.Value = alarmM1A;

app.TRIP.Value = tripM1A;

app.CHA.Value= processM1A;

% To plot data in UI Axes

data1A(i)=app.CHA.Value;

% data1T(ii)= app.TRIP.Value;

if i<=60

plot(app.UIAxes,data1A,'LineWidth',1.5);

% plot(app.UIAxes,data1T,'LineWidth',1.5);

else

plot(app.UIAxes,data1A(end-60:end),'LineWidth',1.5);

end

title(app.UIAxes,'Live Trend Module 2 Channel A');

xlabel(app.UIAxes,'Time in seconds','Color','k');

ylabel(app.UIAxes,'Amplitude','Color','k')

ylim(app.UIAxes,[0 fullscaleM1A]);

grid(app.UIAxes, "on");

pause(0.1)

i= i+1;

end

Answer 1

[Pratyush Swain]

Hi Aditya,

Your current code is structured to plot only one channel of data ("data1A") on your UI Axes. To plot multiple channels including trip and alarm lines, its important to use "hold on" and "hold off" to ensure that all the lines are plotted without erasing the previous ones. Here's a modified version of your code which demonstrates plotting for trip and alarm values.

i = 1;
data1A=[];
data1T=[];
data1Al=[];
while strcmp(app.Switch.Value, 'On')
    % Generating random values for trip,alarm & process
    tripM1A = 80 + rand(1)*20; 
    alarmM1A = 50 + rand(1)*10; 
    processM1A = rand(1)*100; 
    fullscaleM1A = 100; 
    
    % To plot data in UI Axes
    data1A(i) = processM1A;
    data1T(i) = tripM1A;
    data1Al(i) = alarmM1A;
    
    if i <= 60
        plotRange = 1:i;
    else
        plotRange = (i-59):i;
    end

    % Ensuring previous plots are not erased
    hold(app.UIAxes, 'on');
    
    plot(app.UIAxes, plotRange, data1A(plotRange), 'LineWidth', 1.5, 'Color', 'b'); % Process data
    plot(app.UIAxes, plotRange, data1T(plotRange), '--', 'LineWidth', 1.5, 'Color', 'r'); % Trip line
    plot(app.UIAxes, plotRange, data1Al(plotRange), ':', 'LineWidth', 1.5, 'Color', 'g'); % Alarm line
    
    % Hold off after plotting
    hold(app.UIAxes, 'off');
    
    title(app.UIAxes, 'Simulated Live Trend');
    xlabel(app.UIAxes, 'Time in seconds', 'Color', 'k');
    ylabel(app.UIAxes, 'Amplitude', 'Color', 'k');
    ylim(app.UIAxes, [0 fullscaleM1A]);
    grid(app.UIAxes, "on");
    
    pause(0.1);
    i = i + 1;
end            

Please note I have used random data values since I do not have access to Modbus serial connection.Also the "hold" commands need the axes as a parameter. I have also attached the demo app containing the above implemention for your reference.For more information please refer to:

1-https://www.mathworks.com/help/matlab/ref/hold.html

Hope this helps.

[Aditya]

The app is working fine. But it is not deleting the previous data . It keeps it in small chunks. I want it to clear the data after 60 seconds. Is it possible. I want to delete the previous plots after 60 seconds of like sometime.