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Change the buffer size during a simulation

Asked by Ali Ghader on 16 Aug 2017
Latest activity Commented on by Walter Roberson
on 19 Aug 2017
I am trying to log a reading from a sensor for 2 seconds when simulink starts in order to define a suitable size for the buffers/matrices that I am using in signal analysis.
-Would there be a way to change the size of the buffer after the start of the simulation ?
*I tried to pause the simulation and update the parameters and resume but unfortunately it didn't work, it still gives me the same error: ""Cannot change parameter 'Output buffer size (per channel): (N)' of 'RotorBalancing/Subsystem1/Buffer' while simulation is running""
I used this code for this sake:
set_param('RotorBalancing','SimulationCommand','start');
set_param('RotorBalancing','SimulationCommand','pause');
set_param('RotorBalancing/Subsystem1/Buffer','N','1000')
set_param('RotorBalancing/Subsystem1/Buffer2','N','1000')
set_param('RotorBalancing','SimulationCommand','update');
set_param('RotorBalancing','SimulationCommand','continue');
  • I tried to enable the buffer after the 2 seconds and I still got the same error.
-In case changing the buffer size won't work. Is there a better option to store the signal and prepare it for signal analysis (FFT) ?

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1 Answer

Answer by Saurabh Gupta on 18 Aug 2017
 Accepted Answer

Buffer block dialog parameters can not be modified while the simulation is running or paused. You can observe this by trying to interact with the parameters in Simulink environment, and you will notice that they are edit-disabled.
If you want to post-process the signal, you can always log the signal to a MAT file or the workspace and then, use MATLAB functions for FFT to perform the required analysis. The following documentation lists all the relevant functions in MATLAB.
Hope this helps!

  7 Comments

You might possibly need to switch over to doing fair parts of it as a MATLAB Function block that uses coder.varsize to allow variable sized arrays.
The buffer size changes that might be desired: are there a fairly limited number of different permitted sizes, such that you might be able to use a switch block or triggered subsystems or the like, one copy of the subsystem for each of the limited number of different sizes?
Thank you again for the help
Actually it would much more convenient to me to store the signal in other than buffers cuz I am facing another limitation as described here: https://de.mathworks.com/matlabcentral/answers/352923-how-is-the-buffer-block-filled-in-an-enabled-subsystem
Can the signal be stored in a Matlab function block or you only suggest it for signal-processing ?
Sorry, I do not know much about those topics.

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