MATLAB Engine API for Python: changing parameters of the running simulation

Question

I am using the MATLAB Engine API for Python. I have a shared engine in a Python script and then another Python script connected to this shared engine. I would like to ask whether it is possible to change the parameter of the running simulation from Simulink using set_param command. It looks like my following solution does not work. The set_param command in the 2nd script is waiting until sim() command from the 1st script is finished. Thanks in advance.

1st script:

import matlab.engine
eng = matlab.engine.start_matlab()
eng.eval("matlab.engine.shareEngine('my_sim123')")
eng.eval("load_system('scheme123')",nargout=0)
eng.eval("sim('scheme123')")

2nd script:

import matlab.engine
eng = matlab.engine.connect_matlab('my_sim123')
eng.eval("set_param('scheme123/PID', 'P', '15')",nargout=0)

UPDATE: I tried to use set_param('scheme123', 'SimulationCommand','Start') instead, but the following error occured: "You cannot use set_param to run a simulation in a MATLAB session that does not have a display." Is there any other way to change the parameter of the running sumulation with no display?

Phil Goddard · Accepted Answer · 2017-03-21 02:28:18Z

1

This isn't an issue with the Python API. The sim command is blocking - even when used from within MATLAB itself.

To over come this you need to start the simulation using

set_param(gcs,'SimulationCommand','Start')

That will run the simulation to completion. If you need/want to stop it prematurely then use

set_param(gcs,'SimulationCommand','Stop')

answered Mar 21, 2017 at 2:28

Phil Goddard

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2 Comments

user3618276 Over a year ago

I tried to use eng.set_param('scheme123', 'SimulationCommand','Start',nargout=0) instead, but the following error occured: "You cannot use set_param to run a simulation in a MATLAB session that does not have a display." Is there any other way to change the parameter of the running sumulation with no display?

Phil Goddard Over a year ago

You'll need to start the MATLAB engine with the desktop open: matlab.engine.start_matlab('-desktop'). I don't believe you have any other options. You can also use -minimize and -nosplash to avoid the nuicanse of the desktop being displayed.

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