Maximum number of event iterations in Modelica - events

Question

Is there a way to change the value of "Maximum number of event iterations" ,eviter, that is set to 20 in dymola?

Answer 1

It seems like dymosim.ini is not used for regular simulations (Note the version in line 4: dymosim.ini states 1.1, whereas the dsin.txt has 1.4 written in Dymola 2019). I also could not find a function or variable in Dymola to change eviter, so the only solution I can think of is to edit dsin.txt before simulation.
The code below shows how a function could look like which updates dsin.txt and then performs a simulation. Note that the function should be extended for error handling.
function MySim
import Modelica.Utilities.Strings;
import Modelica.Utilities.Streams;
import Modelica.Utilities.Files.removeFile;
import SimAPI = DymolaCommands.SimulatorAPI;
input String m = "Modelica.Blocks.Examples.PID_Controller"
annotation (Dialog(__Dymola_translatedModel(translate=false)));
input Integer iterations = 40;
protected
String[:] dsin;
algorithm
// initialize
removeFile("dsin_custom.txt");
removeFile("dsin_export.txt");
SimAPI.translateModel(m);
SimAPI.exportInitialDsin("dsin_export.txt"); // exports simulation setup of active model
// write custom dsin file
dsin :=Streams.readFile("dsin_export.txt");
for i in 1:size(dsin, 1) loop
if Strings.find(dsin[i], " # eviter ") > 0 then
dsin[i] :=Strings.replace(dsin[i], "20", String(iterations));
break;
end if;
end for;
for i in 1:size(dsin, 1) loop
Streams.print(dsin[i], "dsin_custom.txt");
end for;
// simulate and open file
// using simulateModel would generate a new dsin file, so dymosim.exe must be called
SimAPI.system("dymosim.exe -s dsin_custom.txt "+m+".mat");
// workaround: create empty plot to open result, as there is no load-result command
DymolaCommands.Plot.createPlot(y={""}, grid=true, filename=m+".mat");
end MySim;
The function translates the selected model, exports the simulation setup, edits it as needed, performs the simulation and opens the result file - so it is basically a customized simulateModel-command.
With the features described in 7.2 Extendable user interface – menus, toolbars and favorites in the Dymola User Manual Volume 2 a shortcut to the function can be created in the Dymola GUI, which allows to perform the simulation for the selected model. This would make the function as convenient to use as the regular simulate button.

Answer 2

Since Dymola 2020x there is an advanced variable that should do exactly that.
From the 2020x changelog:
Advanced.Simulation.MaxEventIterations The maximum number of evnet
iterations, eviter. Use with care, since too small value will lead to simulation failure.
The default value is Advanced.Simulation.MaxEventIterations=20
Additionally the precision for the iteration can be changed:
Advanced.Simulation.EventEpsilon The time resolution for events, eveps. The
default value is Advanced.Simulation.EventEpsilon=1e-10