Solve differential equation with two variables in Simulink

Question

I have a differential equation of the form:

xs'' = rhs * theta

to solve in Simulink, where xs and theta are variables and rhs is a numerical constant. So far, I've got this:

but it's incomplete and I feel it is wrong. How can I simulate this equation in Simulink?

Regards

Answer 1

This works as expected:

Thanks to @Ander Biguri!