Why do the 2 "identical" systems in the file attached lead to different results?

Dear all

Why do the 2 "identical" systems in the file attached lead to different results?

Answer 1

[Walter Roberson]

It is not clear to me where you are looking?

Your top system has an algebraic loop, in theory; in practice it does not only because you have a gain of 0 on the feedback, so the information from the output is not used and that input acts like a constant.

Your bottom system has something that is not connected, and it is not obvious that the floating line will default to 0.

When I look at the scope of Gain and Gain1, the two are identical, so I do not know where you are seeing a difference?

You should repair your model so that it has no algebraic loop. https://blogs.mathworks.com/simulink/2015/07/18/why-you-should-never-break-an-algebraic-loop-with-with-a-memory-block/

[Diego Stutzer]

Hi Walter

Thank you for you answer. The information and instructinos on the link you provided do solve my problem and make the systems behave identical.

Thank you a lot!