How to check a signal value in the 'startFcn' for a Simulink model right before the model executes?

I have a constant block in my model which acts as a source for a complex subsystem. My colleagues use this model. Now, I would like to throw an error and prevent my colleagues from running the model if the value of this constant block is 0. The problem I am facing is that I cannot use the output of the constant block as that would mean the model has started simulating. How can I meet this end goal?

Answer 1

[MathWorks Support Team]

Here is one solution for you:

• The trick here is to read the block's "parameter" instead of the block's output "signal".
• Note that a "signal" value can only be generated during simulation. So, as you rightly stated, reading a signal would mean starting the simulation.
• You can use the "get_param" function to get the parameter values of the constant block in your model. For more information refer to this link:

https://www.mathworks.com/help/releases/R2021b/simulink/slref/get_param.html

• Use "get_param" in the "startFcn" and show an error dialog if the value of the constant block is 0 using the "errordlg" function. Refer to the following link for more details:

https://www.mathworks.com/help/releases/R2021b/matlab/ref/errordlg.html

Similar to obtaining values, you can also set values programmatically. Refer to the following link for more details:

https://www.mathworks.com/help/releases/R2021b/simulink/ug/parameter-values-and-specification-methods.html