How can I use COM objects with a "parfor" loop via "actxserver"?

I am creating a MATLAB script where I invoke commands on a COM server created with "actxcommand". For example,

MotorCAD_File = 'C:\mymcadfile';

parfor (i = 1:10)
    mcad = actxserver('motorcad.appautomation')
    invoke(mcad, 'LoadFromFile', [MotorCAD_File '.mot']);
    invoke(mcad, 'Quit');
    mcad = 0;
end

When I run this code with more than one parallel worker, I get the following error:

Error using MotorCAD_DiaANDMagnet_Mot_Creation
Error: The remote procedure call failed

How can I avoid this error?

Answer 1

[MathWorks Support Team]

When using "actxserver" with a "parfor" loop, it should be defined as a "parallel.pool.Constant", as follows:

a = parallel.pool.Constant(@() actxserver('motorcad.appautomation'));

parfor (i = 1:10)
    mcad = a.Value;
    invoke(mcad, 'LoadFromFile', [MotorCAD_File '.mot']);
    invoke(mcad, 'Quit');
    mcad = 0;
end

For more information on "parallel.pool.Constant", please see the following documentation link:

https://www.mathworks.com/help/releases/R2021b/parallel-computing/parallel.pool.constant.html

Using the code above, this error should not occur.