For a co simulation FMUs the FMU and Modelica model exchange input/outputs at discrete communication points. The FMU wrapper in System Modeler offers two ways of controlling that, using an externa trigger signal (useTriggerInput_=true) or periodically with the step size given by step_ (useTriggerIntput_false)

Got it, but are the "step" and "stepTrigger" variables that appear in modelica code of the imported FMU created by SM at the time it opens or are they in some "hidden place" in the FMU? I'm asking because I'm developing an application where I execute SM FMU's.

I'm suspecting you are simulating the imported FMU with useTriggerInput_=true, but without anything connected to the trigger. You could connect it to a BooleanPulse or SampleTrigger, but the easiest solution is to simply set the useTriggerInput_=false and specify a step_ size.

I hope that helps.

Otto

I'm using System Modeler 12.1, where can I find those simulation options?

It's a parameter in the model that is generated when you import the FMU. So you should get that Co-simulation tab when you open the generated model.

Otto

Hi again, I was wondering what the

useTriggerInput_

parameter means? is it a kind of enable signal generator for the solver?

in the FMU that I generated in systemModeler there is a variable:

Interfaces_.Boolean_DiscreteInput stepTrigger_ if useTriggerInput_  >>;

I noticed that SM just generate it if the FMU is for Co-Simulation. So if I'm correct it is a synchronization mechanism for other programs or process that simulate other part of the system.