How to instantly update the plot by getting values from a Scale widget?

[menator01]

You might can use this approach

import tkinter as tk

class Window:
    def __init__(self, parent):
        self.slidervar = tk.IntVar()
        self.slider = tk.Scale(parent, from_=1, to=10, orient='horizontal')
        self.slider['variable'] = self.slidervar
        self.slider.pack()

        self.button = tk.Button(parent)
        self.button['text'] = 'Open Window'
        self.button.pack()


class TopWindow:
    def __init__(self):
        window = tk.Toplevel(None)
        window.geometry('200x200+500+300')
        self.label = tk.Label(window)
        self.label.pack()

class Controller:
    def __init__(self, window):
        self.window = window

        self.window.button['command'] = self.openwindow
        self.window.slider['command'] = self.update

    def openwindow(self):
        self.topwindow = TopWindow()
        self.topwindow.label['text'] = self.window.slidervar.get()

    def update(self, event):
        self.topwindow.label['text'] = self.window.slidervar.get()

if __name__ == '__main__':
    root = tk.Tk()
    root.geometry('200x200+250+250')
    Controller(Window(root))
    root.mainloop()