why the gain P in PID block when I, and D are 0 and a gain block alone are not equivalent?

hello, I want to tune a PI controller using the self-osciallation model, so I want to use a P controller first. I used a gain block to emulate the P controller and I can see the oscillations and it is fine but whenver I use the P-Controller and the value of I and D to 0, I find a different behavior of the output. so why is not the same behaviour?

best regards,

[Birdman]

Before this question, have you checked the latest answers of mine in the following questions of yours? If you did, why didn't you respond positive or negative?

https://www.mathworks.com/matlabcentral/answers/380885-what-do-the-variable-p-i-and-d-mean-in-pid-z-in-simulink?s_tid=prof_contriblnk

https://www.mathworks.com/matlabcentral/answers/380400-why-i-ma-getting-error-in-simulating-the-matlab-function?s_tid=prof_contriblnk

Answer 1

[SimTec]

Hello Birdman, Sorry I did not see your comment as for when I looked at the comment I still see mine as the last but you have added those 02 very explanative pictures and thanks so much for that because now I know what should I write in those boxes. so from what I understood if I use the parallel form of PID is must work.