Embedded System Test Automation Framework from scratch hints (Im so lost)

sorry for asking this question, I´m more an engineer working with some programming tasks and not much of a programmer, which means, always learning all the time, not knowing anything T-T snif

So this is the thing: I started another job in an embedded system testing, we have the real equipment connected to yadda yadda a NI equipment. There´s a team that has programmed a simulator and then another like a data acquisition program, in the simulator it´s possible to see inputs and outputs, messages, etc and force some conditions. With the data acquisition it´s possible to basically find all variables printed from the SW code running the system, check the output and input values. For what I´ve understood, there is communication serial and via ethernet.

So now I´ve seen that the testing and so far has been manual. This is asking for automation like crazy!! There´s no reason not to do it.

My question is how to start to build a framework to automate the tests.

The manual testing is something like this: with the simulator you set the initial conditions of the system, then you check the variables that tell you the status with the data acquisition program. Usual stuff.

The problem is that I dont know where to start. My experience is that in the past I was working in a very simular environment but we had Vector CANOe and some programmers were getting a testing framework and then I could program everything in CAPL to test my function: like everything, I could make my own functions to get the inputs and transform them, functions to set the initial preconditions, etc, it was so great. But I didnt get how the programmers were setting the framework. I understand that they were linking the variables available to the framework as they found them in the code? Or maybe linking to a model in Labview from the NI cards?? Super lost. Then in the long past, I was working in a system which was programmed in C++ and my test lead programmed in C++ another module which was running with the rest of the code of the system, getting the variables from there and then adding some functions for us to test, in my case I was adding some variables, transforming them, then creating files for every test and adding some report stuff in Latex. But this is not possible now. I can check the code but not add another module to test. I asked if the guys programming the data acquisition or the simulator were planning to add a test automation and they told me that the had the idea from the simulator team but they can´t because the data acquisition can connect to all the system and get every variable but the simulator can´t - like what? But both are running on the same PC of the simulator! How is that possible? I´m lost.

Super lost, sorry for the noob, I guess, question and absoluty every hint and suggestion would be much appretiated!!

Have a nice day!