Alert reTerminal board if is powering from UPS reTerminal E10-1

I have an expansion board reTerminal-01 with the reTerminal seeed studio board.
I would like to know if it 's possible to know when the board is supplying from the UPS or from the main power supply 24Vdc.
Is there any bash command or python librairies for doing that ?
Best regards,

We currently only have the battery status on the screen.

Where is this option?