How I can define a varying parameter in Simulink Test?

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I am designing a Test Harness for my model. I have a parameter in the simulink model(a gain) and I want to develop a test sequence to test the sensitivity of my model with respect to this parameter. simply, I want to design a DOE for my model. I defined the parameter in the test sequence and I define that in the Model Explorer, too. But, I received the below error. Could you please guide me that how I can define a parameter that I can change in each test by Test Sequence Editor block?
Thanks for your consideration and time.
regards, --------- "Constant or Parameter data 'AAA' on left hand side of an expression.
State 'step_2' "AAA" ----------
  1 Comment
Ayyoub on 25 Feb 2016
Edited: Ayyoub on 25 Feb 2016
Thanks for your answer Akshata. I tried your solution, but "symbol wizard" window is opened and ask to give a role(input, constant, parameter,...) to the name of gain block. And, all of these options cause another error.

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Accepted Answer

Sarah Dagen
Sarah Dagen on 10 Jun 2019
To change this gain value from a test sequence block, you need to follow a pattern such as in the image below:
You need to declare evalin, set_param, and num2str as coder.extrinsic in the initialization step of the test sequence. You can then use these commands in sequence steps to change the gain value in the base workspace during simulation.
Pratik on 13 Feb 2024
Hi, if varibels are already in model workspace then is it possible to vary in test sequncve block?
Sarah Dagen
Sarah Dagen on 13 Feb 2024
If you promote your model workspace parameter to be a model argument, you can then use the Parameter Writer block to change its value. The approach has the advantage of simpler code in the Test Sequence block (no coder.extrinsic, set_param, etc.). You simply add an additional output from the Test Sequence block and use that to drive the Parameter Writer.

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More Answers (1)

Chandrasekhar on 15 Feb 2016
i guess you want to change the gain value while the simulink model is running. you can do that by giving the below command in your test sequence
set_param(<gain block name>,'Gain',<value>)
Chandrasekhar on 2 Mar 2016
Could you please let me know the context how you want to change the gain value.
Ayyoub on 4 Mar 2016
Edited: Ayyoub on 4 Mar 2016
There is a gain in my Simulink Model, and I want to change it after each transition in Test Sequence block. For instance: (A is the gain in my Simulink Model)
step 1 after(2,sec) step 2 .... A=1; %(value of gain in step 1)
Step 2 after(4,sec) step 3 .... A=5 %(value of gain in step 2)

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