MATLAB: The second s-function only run at first step in multiple S-Functions cases

Question

I am running a simulink model with 2 S-functions (more in the future), while it cannot gives a correct result. When using some printf in my codes, I found that the second s-function runs only at the first step, although the first s-function runs continuously each step. What makes me confused is that when run the two S-function separately, by using workspace for data transmission indirectly, it works. Thus, I think there should be some tricks about running a model where the s-function cooperating with each other. Could someone give me some hints about it?

In the attachment is my model with the two C-codes.

My problem is that my simulink model can only support one s-function running continuously with fixed step (0.001s). When connecting s-function to another, the second s-function runs only at the first step.

Thank you for your reading

Answer 1

Now I solved this problem Take care of the sample time setting when you connect the separate s-function blocks!

if true
  ssSetNumSampleTimes(S, 1);
end

I changed the value to -1 then it works.