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For Loop Iterator Not working as expected.

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ANKUR WADHWA on 20 Mar 2019
Commented: Fangjun Jiang on 25 Mar 2019
i was expecting a staricase signal as the output with final value as 20 which will be displayed on the scope connected as shown in screenshot.
and the XY graph should show the same signal ,however i am not getting the expected behaviour for the scope but the xy graph is getting
plotted correctly ,can someone explain what is going wrong and how it should be corrected to get the defined behaviour.
Main Model
Inside For Iterator Subsystem
For Iterator System Properties
XY Graph Properties
XY Graph After Model Simulation
Scope Output Inside For Iterator Subsystem
Scope output In the Main Model
ANKUR WADHWA on 21 Mar 2019
Removed the comma(,) added mistakenly at the end of the link which is working now..

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Answers (1)

Fangjun Jiang
Fangjun Jiang on 22 Mar 2019
You need to understand the difference between simulation steps and iteration steps. It looked like you ran simulation for 20 seconds. To simplify, let's assume your simulation step size is 1 second. When the simulation is run at time=1 second, the "For iterator subsystem" is executed 20 times. It itrated from 1 to 20 times. When the 20 iteration is done, the result is output to the Scope. At time=2 second, all these 20 iteration is done again and so is for t=3,4,5,... seconds.
So the Scope in the main modle always show 20. The scope inside the "For iterator subsystem" is also mostly 20 but it also shows the iterator goes back to 1.
XY Graph is different. It just shows the X and Y value pair. Because it is inside the "For Iterator subsystem", it probably shows all the value. But you will get the same graph even if you just ran the simulation for 1 or 2 seconds.
Fangjun Jiang
Fangjun Jiang on 25 Mar 2019
The value did change from 1 to 20, but the time logged are all the same as far as Simulink is concerned.
On your Scope (both inside and outside the "For Iterator subsystem" block), go to setting or configuration properties, log the data using "structure with time". Run the simulation for just 1 or 2 steps and observe the data.

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