Hello @Balardo, you are right - there was a bug in schema validation for /json/all endpoint. It should be fixed in the next release. According to the direct Modbus unit register access - you can use e.g. http://<your IP>/json/unit_register/UART_15_2_42 to get the ambient_light register: {"status": "success", "data": {"name": "ambient_light", "value": 122.51519775390625, "glob_dev_id": 2, "dev": "unit_register", "circuit": "UART_15_2_42", "unit": "lux"}} Register values has been also added to the web control panel: You can test it by install the test version: sudo su apt update && apt install evok=2.3.3.test.20200923165635*