Solution
After you import your model in VeriStand, you can access parameters and signals if your model has built with certain settings.
To explain this, suppose you have the simple model below.

The Subsystem box contains following code.

Here MyGain has specific parameter which is labeled as mygainparameter as Gain.

Basically if you build this Simulink model, you can access input (myinput) and output (myoutput) but you cannot see intermittent value like the value after MyGain.
If you want to see this value in VeriStand, set Test Point as shown below.
In this case, test point is set for the wire labeled Middle Value.

Then your model looks like below.

In Simulink Configuration Parameters window, go to Interface category and check signals in "Generate C API for" item.

After you build your model, import it in your VeriStand project.
Then check Parameters and Signals. In this case, you can see mygainparameter under Parameters and Port1:Middle Value under Signals.

