Code Error When Trying to Plot Scope to Matlab Graph

What would cause the code "plot(ScopeData.time,ScopeData.signals.values,'or')" to have an error and how to fix it. This is my code:

x0 = -1;
A = -2;
B = 1;
C = 1;
D = 0;
t = linspace(0,10);
u = 2 +3*sin(3*t);
[y,~]=lsim(A,B,C,D,u,t,x0);
plot(t,y);
hold on
plot(ScopeData.time,ScopeData.signals.values,'or');
xlabel('time(s)');
ylabel('x(t)');
legend('lsim','simulink','Location','northwest');

This is my Simulink

[Walter Roberson]

Your code does not assign to ScopeData and does not call sim() so we have no expectation that something in the model might have assigned to ScopeData .

[Kassandra Krinke]

How do I fix that? I don't know Matlab or Simulink well.

[Aghamarsh Varanasi]

Hi Kassandra,

You are trying to plot ScopeData. ScopeData, which seems to be a structure, doesn't seem to be defined in the current scope. Could you please share your Simulink (.slx) file, pertaining to your model.

[Kassandra Krinke]

I have attached my Simulink and MatlabCode

Answer 1

[Aghamarsh Varanasi]

Hi Kassandra,

It seems that you want to plot the Simulink Scope Data in MATLAB. Data Import/Export from Simulink can be set using the Configuration Parameters dialogue box. You could open the dialogue box from Simulation > Model Configuration Parameters, or press Ctrl+E. In the Data Import/Export Tab, you can select the variable in which you want to export the Simulink data. By default, the data is exported into a variable named ‘out’.

Hence your matlab code would be,

x0 = -1;
A = -2;
B = 1;
C = 1;
D = 0;
t = linspace(0,10);
u = 2 +3*sin(3*t);
[y,~]=lsim(A,B,C,D,u,t,x0);
plot(t,y);
hold on
xlabel('time(s)');
ylabel('x(t)');
legend('lsim','simulink','Location','northwest');
 
%The output of simulink is stored in a variable 'out'
%Access Scope data from out variable
 
time = out.ScopeData.time;
signals = out.ScopeData.signals.values;
 
plot(time, signals, '*g');

Make sure that you simulate the Simulink model before running the MATLAB Code.

Hope this helps.

[Kassandra Krinke]

Thank you so much! That helped a lot.