Sequential work with the port

[maratk1n]

Is that correct?

Yes that's right. This is problem number 1. I have not tried your method yet, because no access to the board. I would like to monitor the reception with time, because if my request does not reach board for some reason, she will not answer me, no matter how much time I wait. For this reason, I make repeated requests after the timeout.

All the story around it, how things in other threads are, are not the problem, more the motivation, as far as I can see.

I can not say with certainty. But I tried to call directly device->switchState(7, true); from algorithm, which got the error that you can not call the methods of another thread, being not in the main thread. Therefore, I connected them with signals.