If both “set_value” and “set_text” (each with its own parameter) do not work, then you need to check the widget name and the absence of spaces inside quotes in the names of commands, parameters, etc.
For text widgets, I mostly use “set_text”. I don’t see the point in “set_value”, because anyway, the number needs to be converted to text before inserting it into this command.
You can test the execution of commands using the terminal program that comes with Stone Designer. So it is much easier to learn the features of the execution of each command than to change the firmware of the microcontroller every time. I just tested using the terminal command
ST<{“cmd_code”:”set_value”,”type”:”line_series”,”widget”:”line_series1″,”index”:4,”value”:38}>ET
and it works fine, the line on the graph changes.