How can I slow down a MATLAB function in Simulink?

I have a MATLAB function with an external closed loop. In order to simplify my problem, assume i'm trying to perform the following diagram (see picture). The problem is that I want this function to perform one iteration per second, but since this is a continuous model (I can't do the whole system discrete at this point) the iteration makes thousands and thousands of values per second, and my output is practically zero.

I want the MATLAB fcn to take one set of values per second, and hold those values. I'm not sure how to do this! please help!

Thank you in advance.. I don't know what else to do I need to end this simulation ASAP