Reply To: 12 V sense check before i do it

I’d check the potential current first. A USB device may be permitted to take up to 3A, and if the USB socket allows multiple connectors then could be more. Then there is the plotters power needs which will add to that current. Then check the current capacity of the cable used and fuse fitted. You might also insert an extra fuse for the USB socket. It will probably be okay but better the fuse goes than the cable.