update variable with the time

Hi, im trying to update one var each period of my time simulation. Im working with simulink and simevents. But I have this problem. after compare one measurement with other value, i want to set on variable "x" to 2, and in the second period, I have to do the same comparision, and update or not the var "x". I have time-generator of simevents, to count my interval but I have two options, I've created only blocks or one MATLAB function, with code. How can I add this time counter, in a for loop to update "x"? And Do exist some way to create one variable in simulink and update it??

Thanks a lot!!!