How to interrupt Simulink when running through Python? (Requirements: Monitoring? Waiting for the interrupt signal from users)

Hello! I'm new to Matlab and now working to control simulink through python.

• Goal: I want to interrupt the running of Simulink with the help of the keyboard, but it should be done in a GUI on python. When the simulink model pauses, I can update the parameters of some blocks(or switch the mode of the model).
• Problem: The interruption point of running of the Simuink can only be set before I run the simulink model. E.g. I can set the model to pause at 2s. But I can not interrupt it at any time. Although we can click "pause" on Simluink GUI but I have to only control the simulink model thorugh a GUI built in Python.
• Code: Here I used "set_param" to realize "stop","start","update parameters". But I can not interrupt the model whenenver I want(without setting interruption points bevorhand). The code can not caputure the keyboard event, when I pressed ‘space’ on thekeyboard.

This is the code of Python(3.8).

import matlab
import matlab.engine
import numpy as np
import matplotlib.pyplot as plt
import keyboard  #monitor the event from keyboard

def Change2VM():
    eng = matlab.engine.start_matlab()
    env_name = 'simpleSinEnvV3' # define the name of Simulink model
    # eng.load_system(env_name)   # load
    eng.set_param(env_name, 'SimulationCommand','Pause') # interrupt the model
    eng.set_param('simpleSinEnvV3/Modus','value', '1', nargout=0) #change the mode to VM
    eng.set_param(env_name, 'SimulationCommand', 'continue', nargout=0); #cancel pause and continue the simulation
    print('VM Modus is on\n')

def main():
    # load the simulink model
    eng = matlab.engine.start_matlab()
    env_name = 'simpleSinEnvV3'
    eng.load_system(env_name)
    duration = 5 # in seconds. How long dose this simulation run.

    eng.set_param(env_name, 'StopTime', str(duration), nargout=0) # when to stop
    eng.set_param('simpleSinEnvV3/Modus','value', '2', nargout=0) # set the modus to "EM" at the beginning
    eng.set_param(env_name, 'SimulationCommand', 'start', nargout=0) # run the model
   
    print('Wait for key')
    keyboard.add_hotkey('space', Change2VM, suppress=False, timeout=1, trigger_on_release=False) # triger the intrruption
    eng.set_param(env_name, 'SimulationCommand', 'stop', nargout=0) # stop running the model

    t = np.array(eng.eval('out.t.Data'))
    y = np.array(eng.eval('out.y.Data'))
    eng.quit()

    # show the results
    fig = plt.figure(figsize=(5, 5))
    plt.plot(t, y[:, 0], '-', label='VM')
    plt.plot(t, y[:, 1], '-.', label='EM')
    plt.plot(t, y[:, 2], '--', label='HB')
    plt.legend()
    plt.show()

main()

This is my simulink model(Matlab2016a), i want to shift the output from EM(case2) to VM(case1), when I pressed "Space" on keyboard.

[鹏涛 谢]

But it' doesn't work. The program has no response, when I pressed "Space".

From the picture we can konw, "case 2" is never been activated.

Answer 1

[Ayush]

I understand that you want to pause the simulation in between, perform some action, and resume the simulation later. You can utilize the Python’s capability of detecting a key press to pause/resume the simulation. Here is the skeleton code for that:

# to pause the simulation 
while True: 
    if keyboard.is_pressed("your_key"): 
        eng.set_param('modename','SimulationCommand','pause') 
        break 
# to resume the simulation 
while True: 
    if keyboard.is_pressed("your_key"): 
        eng.set_param('modename','SimulationCommand', 'continue') 
        break 

You may refer to Run Simulations Programmatically - MATLAB & Simulink - MathWorks India for further information on how to pause and continue the simulation.