How can I obtain the data from the scope for a waveform

Hi, I need data from the scope at a certain time. The waveform obtained is sinusodial. I've connected "To simulink" from where I want to get the data. I need to get the value of the waveform at time 4.85. I think this is one of the basic questions. I am not so sure of syntax of the command. Please help.

[John D'Errico]

It looks like you got an answer, but you are not using it properly. Your issue, not that of the person who answered the question.

[Shivakumar]

No, I didn't get the answer. I tried his example to my problem. I am not able to get solution to my problem. If I got the answer, I have accepted his answer. Please check that my question is explained in the last two comments. I am still in need of the solution.

[Mischa Kim]

I have to concur with John, I believe I did provide an answer. One which you even got to work. I believe so especially because I am confident in your ability to check out your simout1 object, identify its time vector component and adapt the syntax I showed you accordingly.

I am sure you did not mean to, but you might come across as one of those constantly dissatisfied users that eventually are flagged (figuratively) in the contributors community.

[Shivakumar]

Kim, Please don't take me wrong. I flagged it because I want to make the question active and to get the answer. I don't have any dissatisfaction or complaints on your given answer. There are no other wrong intentions, Kim. I thank you for taking time to answer my question. If you go throw my comments, you will understand my problem of not getting the required solution.

Answer 1

[Mischa Kim]

One option would be to add a Digital Clock block as shown below and set the sampling time to 4.85. This way this time stamp is automatically added to your time vector that is saved in the workspace.

In MATLAB you can then simply search for the data point at t=4.85, e.g.,

 hold on 
 plot(tout,simout(:,2))
 plot(tout(tout==4.85), simout(tout==4.85,2),'rs') % for the above model

[Shivakumar]

Hi, I dont want to plot the data. I want the value at 4.85 seconds to be stored as a variable A in the M-file.

[Shivakumar]

This is the syntax I have to get the maximum value of a waveform.

for i = 1: length(simout1.time(:,1))
  if simout1.time(i,1) == 0.1
     j = i;
     break;
  end
end
j
max_val = max(simout1.signals.values(j:end,1))

In the same way, I need a code to get the data exactly at 4.85 seconds.

[Mischa Kim]

Just as shown above, I'd assume (since I do not know the exact structure of your data)

 val_485 = simout1.signals.values(simout1.time(simout1.time(:,1)==4.85),1);

[Shivakumar]

First I am trying the same kind of solution for the model example you gave above. This is the error I got when I used the above command.

??? Attempted to access simout1.time(:,1); index out of bounds because size(simout1.time)=[0,0].

[Mischa Kim]

If you are using my example model you also need to use the attached code and variable names. In this case

 val_485 = simout(tout==4.85,2);

will work. In my last comment I was trying to guess your data structure and come up with a solution. Notice that your workspace variable is called simout1 whereas mine is simout. So the following command "should" work for your model (and not mine)

 val_485 = simout1.signals.values(simout1.time(simout1.time(:,1)==4.85),1);

[Shivakumar]

For the command

val_485 = simout(tout==4.85,2); This is the error I got.

??? Index exceeds matrix dimensions.

[Mischa Kim]

Double-click the simout block and set Save Format to Array. You probably have a different setting there. When I run the model I get in the MATLAB command window

 val_485 = simout(tout==4.85,2)
 val_485 =
  -0.990546535966713

[Shivakumar]

I got the same answer. But I tried the same to my model but I am not getting the result. Instead, it is showing that the matrix is empty. I've attached the model here. I need to find the value of both simouts at 4.85. I've tried different formats in simout. Please help. Thanks in advance.

[Shivakumar]

The data format is structure with time

[John D'Errico]

My guess is that testing for t == 4.85 is a problem. Testing for (abs(t-4.85)<10*eps) might be a better idea. It might also resolve why the poster failed to get it to work.

[Mischa Kim]

John, with the Digital Clock you can set an exact time stamp in the tout vector.

Shivakumar, what needs to be done (initialized) to run your model?

[Shivakumar]

I've attached the model, Kim. I initialize the model by setting torque.

[Mischa Kim]

In this particular case only (there is a time stamp at t = 4.85) you can simply find the value with

 simout.signals.values(find(simout.time==4.85))

The Digital Clock block is not necessary.

[Shivakumar]

 simout.signals.values(find(simout.time==4.85))

ans =

Empty matrix: 0-by-1

This is the result I got, Kim

[Mischa Kim]

Shivakumar, I downloaded the model you attached in your last comment, and ran it. I get

 simout.signals.values(find(simout.time==4.85))
 ans =
    1.6031

[Shivakumar]

I still get the same problem. I use MATLAB 7.6.0. Do you think different versions is making the difference here?

[Mischa Kim]

Possible, but I do not think so.

• Do you see the object simout in the workspace?
• When you type simout.signals.values and simout.time do you get the values of the two arrays?

[Shivakumar]

Yes for both questions.

[Mischa Kim]

What happens, when you execute...

 simout.time(end)
 ans =
    5
 find(simout.time==4.85)
 ans =
    97001
 simout.signals.values(ans)
 ans =
    1.6031
 simout.signals.values(find(simout.time==4.85))
 ans =
    1.6031

[Shivakumar]

I dont know why it is showing

ans= empty matrix 0 by 1

[Shivakumar]

I thank you Kim for your effort and time. This command helped me to get the answer.

val=simout.signals.values(97001)

I thank you very much. :)

[Mischa Kim]

Excellent. Would you mind formally accepting the answer?