Data from simulink to python with "To Workspace" block

Hi everyone,

I would like to use a controller written in python for a simulink enviornment and therefore I am using the python matlab API. But the problem is how do i get information (state information for each time step) from the simulink enviornment to my python script. I have tried the following in python:

import matlab.engine
import matplotlib.pyplot as plt


eng = matlab.engine.start_matlab()
modelName = 'plant'
eng.eval("model = '{}'".format(modelName), nargout=0)
eng.eval("load_system(model)", nargout=0)

# Initialize Control Action to 0
u = 0
eng.set_param('{}/u'.format(modelName), 'value', str(u), nargout=0)
print("Initialized Model")

# Start Simulation and then Instantly pause
eng.set_param(modelName, 'SimulationCommand', 'start', 'SimulationCommand', 'pause', nargout=0)
print(eng.who())
eng.set_param(modelName, 'SimulationCommand', 'stop', nargout=0)
eng.quit()

The simulink model "plant" is attached where I use "To workspace" block to load the data in to the workspace. But I don't know how to get the data now of the object "eng.workspace['out']"

MATLAB version: R2020b

Python: 3.7.9

Thanks in advance

Answer 1

[Deepak Meena]

Hi Patrick,

Out is the variable which store the output of the To workspace block. By default the variable would be if type of Timeseries. To change it to array , go to block parameter->save format , change it to Array.

Now out contains many variable , but the variable you are looking for would be out.simout , so to access that in python:

p = eng.workspace['out.simout'];

[Shubham]

Hello, I am trying the same thing. It still won't let me get access to workspace variable. Not sure what I am doing wrong. Does the version of Python kernel matter? Mine is 3.11 but the link here says it has to be 3.7 How to Interact with Simulink Using Python - File Exchange - MATLAB Central.

Would appreciate your help!