@keyz182
Yes, this topic IS old...er but alas- I need to clarify something as I'm nearing the 'power on smoke test' ; ) for my RatRig VCore 3 with Duet 3 Mini 5+ and really do not wish to see the 'magic smoke' 
In the thread above, there is a reference link to:
Check the table here - LINK REMOVED as I need at least 2 reputation to post links...sigh
When I try that link- it is el broko, non-functional, kaput!
So... I looked around and according to this resource-
duet3d dot kom/en/How_to_guides/Wiring_your_Duet_3
The Duet has an on-board 5V regulator which is powered by the VIN input (12-24V).
Unless you plan to provide an external 5V source, you should at this time check that there is no jumper on Int 5V Disable or 5V Select.
Optionally, external 5V power can be supplied to:
'5V IN' pin on EXT_5V connector. In this case, add a jumper to the 5V Select jumper between '5V_EXT_IN' and '5V_COM' pins, and add a jumper to Int 5V Disable.
In some cases you may want to power the Duet from the 5V output of an SBC connected to the SBC header. Note that the total power of the Duet and peripherals must be factored into the SBC power budget, and should not exceed 1A. Powering the SBC from the duet is not supported. In this case, add a jumper to the 5V Select jumper between '5V_SBC' and '5V_COM' pins, and add a jumper to Int 5V Disable.
Right...so here's the issue-
- My Power supply: Meanwell LRS-350-24 seems adequate enough for this build (New, voltages all look good)
- My Duet 3 MIni 5+ is running in SBC mode with an attached Pi3B+ with its own factory power supply (5.25v 2400 mA)
- The Pi Factory power supply plugs directly into the Micro USB port on the Pi3B+
- The Pi3B+ is connected directly to the Duet 3 Mini 5+ via the supplied 26 pin ribbon cable
- The supplied 26 pin ribbon cable has 5 volts feeding the Duet 3 Mini 5+
- My Panel Due 7 is connected to the Duet Board via IO_0 connector (I'm sure this draws some power)
The documentation here suggests:
duet3ddot kom/en/How_to_guides/Wiring_your_Duet_3
We recommend powering the SBC using its own PSU, to ensure stable voltage and sufficient supply of current to both Duet and SBC.
I know I can power the Panel Due 7 from the 4 wire connector I already wired up, but can also power it via the 10 pin serial cable, (albeit limited to 400mm length)
With these stated power requirements I've already listed, it seems there woukld be a 5v conflict waiting to happen if I don't choose my jumper setting correctly...which is what led me to this thread. 
I'm sure I'll wait to add in some LED lighting,etc as well. Is my Duet 3 Mini 5 + going to be able to handle all this?
Sorry if this question is considered too obvious, I'm apparently missing my marbles today. Oh yeah- prob yesterday too. 
