findpeaks accepts only vector data as it's input arguments. A possible workaround would be to use a Buffer block in between Simulink output and MATLAB Function input
Example:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/567389/image.png)
The above example locates the peaks of a discrete sine wave. The Sine Wave block returns a scalar value while findpeaks expects a vector input. To fix this discrepancy, A buffer can be used to convert scalar value to vector values