RAK 5010-M don't programming

Hello, I have problem with RAK 5010-M it has standard firmware RUI3.x.15
Issue: I try burn my program sending messurments from sensor connected by UART or I2C and i want use rui3 api. but I tried many times different ways and always have no succes. I tryied by Arduini IDE, and visual studio, and I have the same result. What I supposed to do to make it working? And I have another question. It is possible to connect external sensor for example A02YYUW Waterproof Ultrasonic Sensor or use dedicated libraries to some kinds of I2c sensors?

Setup: Custom RAK 5010-m on Arduiono Ide windows 10

Welcome to forum @MmmmPuuu26 ,

The RAK5010 support on RUI3 is still in beta. Though we already released the AT Commands for cellular, many RUI3 API are still not in stable released.

However, I will try to help you. Can you share me the exact RUI3 version you use? I recommend you use 3.5.4 since it is the latest beta. And if you can share the code you tried (even on private message to me), that can be helpful.

Also, what are the external peripherals you are trying to connect and what is your hardware connection?