Matlab has modules like Simulink Real-Time. Using these modules, you can connect mathematical models from Simulink to real devices (microcontrollers, PLM, electronic circuits, etc.) using special I/O modules and thus test their programs on virtual models from Simulink. Also, there is an opportunity to do the same thing, but also using real-time machines (for faster processes, as I understand it). Are there such modules or at least projects/development for Scilab? There may also be other similar environments that allow Hardware in Loop or other similar technologies to be implemented. And of course GNU is desirable. And another thing: maybe there are already some open projects to create I/O modules for PCs? The problem is I must to pay for using Matlab. Even if somehow they got their software for free, I still have to buy input-output modules, and still have to buy a PC with xPC Target.
The creation of virtually binding for microprocessors in the age of general computerization does not seem to me to cause fundamental difficulties. But how to do it. I also suppose, that I can simulate external world for microprocessors using JTAG,SWD(STM32F4 microcontrollers) or another Debug Communication Chanel, but modeling programs like Simulink wil be needed for it also. And also will be needed a lot of utils and drivers... I don't know. Thanks a lot. Enthusiast from Russia (we are all enthusiasts here for this salary...).
Scilab has a more better equivalent to Simulink, known as Xcos. Xcos comes with Scilab and thus requires no seperate installation. Using scilab's serial communication capability in addition to Xcos, we can easily communicate with hardware devices from Xcos. One such project exists in which we access Arduino (a very famous open-source electronic prototyping platform) from Xcos. See https://scilab-arduino.fossee.in/ for details. Also see https://sbhs.fossee.in/ a project in which a laboratory device called as a "Single Board Heater System" is accessed using Scilab-Xcos.
Xcos also offers other simulation capabilities to simulate continuous/discrete time system in open and closed loop, electrical circuit simulation, digital logic simulation, etc.. We are also in the process of porting the Xcos capability on the cloud. This is a relatively new project and is not up yet. You will find it soon on https://fossee.in/
Speaking of other equally good opensource tools, you might want to check out OpenModelica. See https://om.fossee.in/ It also has hardware communication capabilities and was recently tested for Hardware-in-loop simulation.