Mathematica expressions sometimes may replace several WSM blocks. I have searched for help on realExpression, but I have not found much. See, I want to use an expression like this one:
0.25*(1 + 0.15*sin(80*Modelica.Constants.pi time + Modelica.Constants.pi));
Alternatively, You can enter the code in the text view of the model instead of using realExpression. In some cases this might be easier/clearer. (and you can reference other blocks such as blockname.variable)