Hi again,
I'm slowly getting closer to a solution. My model runs fine when I call it using

simulate(mymodel, startTime=250,stopTime=260)

When I try to build it first and then run it via system() I get an error "-34".

buildModel(mymodel)

system("mymodel -override startTime=250,stopTime=260 -r D:\\path\\to\\output.mat")

I can get the build/system approach to work, when I compile startTime and stopTime, too:

buildModel(mymodel, startTime=250,stopTime=260)

system("mymodel -override startTime=250,stopTime=260 -r D:\\path\\to\\output.mat")

this gives me a "0", everything is fine. (And of course I actually don't even need to override start and stop in the system call. However, it will only then also accept a different startTime=251.)

But then I try to rerun the simulation using the last output as input and get an "-1":

system("mymodel -override startTime=250,stopTime=260 -iif D:\\path\\to\\output.mat -r D:\\path\\to\\output.mat")

API-Documentation is not accessible (https://github.com/OpenModelica/OpenMod … HowTo.pdf) and I couldn't find any other documentation of error codes.

edit:
the last issue can be omitted, when the start file (output.mat) is read from the current working directory (without path):

system("mymodel -override startTime=250,stopTime=260 -iif output.mat -r D:\\path\\to\\output.mat")

Oh, this is funny, it works the other way around, too. Init file and output file must obviously not be in the same directory (at least, when they have the same name).

OK: so I have a working solution. Only still would like to understand the "-34" and why I have to compile startTime/stopTime.
Thank you all.
André