How do i create multiple plots in one diagram?

Hello guy im working currently with a robot and i need to visualize the measurements of the robot as a live plot.

I got a matlab script but i just creates one plot.

Here is my script:

function[out]=test_liveplot()
p.dev= '/dev/ttyUSB0';
p.baudrate = 57600;
p.terminator = 10;
s = serial(p.dev, ...
'BaudRate', p.baudrate, ...
'StopBits', 2, ...
'Terminator', p.terminator, ...
'TimeOut',5);
fopen_extended(s);
figure('Name','Live-Plot'); hold on; grid on;
ylabel('velocity [tics/100ms]'); xlabel('time/s');
hl=plot(nan,'r-');
hr=plot(nan,'b-');
out=zeros(0,4);
active=true;

while active
    data=fscanf(s, ... 
        '%d %d %d %d');
    if isempty(data)
        active=false;
        continue;
    end
    out(end+1,:)=data';
    set(hl,'XData', double(out(:,1) )/1000, ...
        'YData', out(:,4));
    set(hr,'XData', double(out(:,1))/1000, ...
        'YData', out(:,4));
    
    drawnow
end
disp('No data left, loop ended.');
fclose(s);
    
function fopen_extended(s)
try 
    fopen(s);
catch err
    if(strcmp(err.identifier,'MATLAB:serial:fopen:opfailed'))
        try
            ports=instrfind('Port', s.Port);
            fclose(ports);
            fopen(s);
        catch err
            disp('couldnt open connection');
            disp('no rights')
            rethrow(err);
        end
    else
        rethrow(err);
    end
end

the robots sends all 4 values to matlab but matlab only creates the plot of one of those values but i need all of them in the live plot.

what do i have to change to get it working?

[Lucademicus]

Do I understand it correctly that of the 4 values, one should represent the x-axis and the remaining 3 are values of the y-axis, hence you want 3 plots?

[Julozert]

@Lucademicus

yes exactly. I want the time as x-axis and the speed value of the right and left motor as y-value

Answer 1

[Lucademicus]

This parts reads the data, the 4 %d's suggests it are 4 doubles which are read:

    data=fscanf(s, ... 
        '%d %d %d %d');

This part sets the dynamic data sources of the X- and the Y-axis:

        set(hl,'XData', double(out(:,1) )/1000, ...
        'YData', out(:,4));
    set(hr,'XData', double(out(:,1))/1000, ...
        'YData', out(:,4));

I'm not sure if 'hl' should be the 'left motor', and 'hr' should be the 'right motor', but the 'YData' is both out(:,4) so these plots are equal.

I am assuming out(:,1) is the x-data, out(:,2), out(:,3) and out(:,4) are pointing to the relevant y-data (your motor speeds):

function[out]=test_liveplot()
p.dev= '/dev/ttyUSB0';
p.baudrate = 57600;
p.terminator = 10;
s = serial(p.dev, ...
'BaudRate', p.baudrate, ...
'StopBits', 2, ...
'Terminator', p.terminator, ...
'TimeOut',5);
fopen_extended(s);
figure('Name','Live-Plot'); hold on; grid on;
ylabel('velocity [tics/100ms]'); xlabel('time/s');
plotA=plot(nan,'r-');
plotB=plot(nan,'b-');
plotC=plot(nan,'g-');
out=zeros(0,4);
active=true;
while active
    data=fscanf(s, ... 
        '%d %d %d %d');
    if isempty(data)
        active=false;
        continue;
    end
    out(end+1,:)=data';
    set(plotA,'XData', double(out(:,1) )/1000, ...
        'YData', out(:,2)); % plotting the 2nd double of the 'out'-matrix
    set(plotB,'XData', double(out(:,1))/1000, ...
        'YData', out(:,3)); % plotting the 3rd double of the 'out'-matrix
    set(plotB,'XData', double(out(:,1))/1000, ...
        'YData', out(:,4)); % plotting the 4th double of the 'out'-matrix
    
    drawnow
end
disp('No data left, loop ended.');
fclose(s);
    
function fopen_extended(s)
try 
    fopen(s);
catch err
    if(strcmp(err.identifier,'MATLAB:serial:fopen:opfailed'))
        try
            ports=instrfind('Port', s.Port);
            fclose(ports);
            fopen(s);
        catch err
            disp('couldnt open connection');
            disp('no rights')
            rethrow(err);
        end
    else
        rethrow(err);
    end
end