@SolomonSlow thank you! As I said before everything works fine when code running without any breakpoints. I see variables refreshing in Watch Window. When I use step by step debugging in Watch Window only first symbol of UART data is refreshing. I guess my code is correct and it's just a debuging problem

@SolomonSlow sorry, I didn't understand you :) A, B and C is true but problem is how to recieve data correctly not how to work with this data. That's what I mean

Now way. I'm working on system that must process the data in real-time by itself.

Thank you but I cant understand why only the first character is changing. GPS doesn't stop sending data, it's true. I can start recieving in the middle of data while debugging, but in this case I would get new buffer starting in the middle of data, not just first character.