How to delay a loop in a function block?

Question

Mario Avila Rodriguez 2021-10-4

0
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https://ww2.mathworks.cn/matlabcentral/answers/1466691-how-to-delay-a-loop-in-a-function-block

回答： Paul 2021-10-5

Hello everyone,

I have the next simulink model.

the function block has the following function:

function t =fcn(N)

t=0;

for i=0:1:N

t=i;

end

But if i add a delay of 1 second in the loop the model does not work, and it just appear a 0 on the display

function t =fcn(N)

t=0;

for i=0:1:N

t=i;

pause(1);

end

How can fix this in order to delay the loop for "N" seconds befor the cycle stars again.

I hope I have explained the issue clear enough.Please let me know if there is any other point that I need to clarify.

Thanks in advance!

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Answer 1

Walter Roberson 2021-10-4

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在 MATLAB Online 中打开

WIthin any one call to a MATLAB function block, you can only emit values for the "current" time.

If you were trying to create a repeating sequence, then

function t = fcn(N)
  persistent state
  if isempty(state); state = 0; end
  if state > N
    state = 0;
  end
  t = state;
  state = state + 1;
end

This code does not rely upon N being fixed. If you change N and the next output would have been greater than N, then it resets to 0. Another design choice would be to instead reset to mod(state,N)

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Answer 2

Paul 2021-10-5

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I tried this in 2019a and it worked exactly as expected. The effect of the pause(1) is to make this (simple) simulation take 12 seconds of real time for every simulation time step. For a more complex simulation it will make the execution of the Matlab Function take 12 seconds each time it's called (which I think could be simply implemented with pause(N), instead of pausing 1 second N times). When I ran the model, in Normal mode (didn't try Accelerator mode), I saw the Display block change from 0 to 12 after I counted to 12 starting when the simulation started running. Are you waiting more than 12 seconds to see the change in the Display block?