identified model acting different in simulink

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gapsna 2018-9-21

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https://ww2.mathworks.cn/matlabcentral/answers/420095-identified-model-acting-different-in-simulink

编辑： gapsna 2018-9-21

Hello All, I am trying to identify a system withe the System Identification toolbox. I took the input and output signals in Simulink. The output was measured through an ADC and a Speedgoat xPC. I got a decent (very) high order TF with 96% fit. But once I import that idtf object to Simulink and give it the exact same input signal, the output I get is over a order of magnitude higher. For reference, this is the Input (DAC) and the output (ADC):

The dentified Model:

and the Simulink response. For this I send the idtf to the workspace and used an Idmodel block and fed it with a step block with the same values as the original input signal (which was also a step block).

am I doing something wrong or not taking something into account?

edit: you cannot really see the Y axis. The measured output signal (first image) is from 1600 to 3000. And the Simulink output (last image) is from 0 to 3x10^4

Thank you for your help.