How to integrate external programs with UniSim?

Question

C++ / C#

Good evening. Is there any information on how to integrate into the UniSim simulation? The bottom line is that we have buttons that will change any variables in, as I understand it, the simulation model, there is this model itself, which rotates on the same machine on which the program with the buttons will be launched. Question - how to send a message, notify the simulation model that the button was pressed? What is the communication protocol, what does it look like?