No Offset, Gain, LDO how do i get the values?

[Milbrot]

I bought in 2019 a Current Ranger R3 Mk2 with OLED Display.
These days i noticed for firmware update i need calibration values.
The firmware on the Current Ranger is probably one of the first firmwares,
sending a '?'+ Enter in the serial monitor is not working i can only see a string "4094 - 5"
printed continuously at the serial monitor.
There was also no label with calibration values attached.

What can i do to get the values?

[Felix]

There was a label provided on the packaging, or inside the box.
If you don't have it calibrated that then the CR digital outputs (OLED or USB/serial) might be off a little bit.
The calibration does not affect the raw output which is directly output from the internal opamps.
The calibration can be done with a known fixed input, and with the latest firmware adjust the OLED values until they match closely to the input.
The LDO value can be adjusted with < and > and the gain can be adjusted with + and -, this is all done over USB serial.

[Milbrot]

So the LDO value is the measured output from the MCP1703 and affect the OLED or USB output (mcu adc is wrong) and the gain has an effect on?
What is a good solution for a known fixed input?

[Felix]

The CR default for LDO is 3300 (mV). The LDO obviously will not be that value exactly, adjust it to what yours reads (GND, "3v") after the CR was powered on for a minute or so.
Calibrating gain: you could simply apply any load, you can do this in any range, I suggest the mA range (least noise sensitive).
Then measure the raw output with the DMM, adjust gain until the OLED reading matches.

[Milbrot]

I will follow your description, thanks for the help.