Duet 2 Ethernet v1.04c + heatbed and E0 Power module add-on

ReVeRb

I know the specs of the board should handle pretty well the heat bed as well as the hotend that I'm using.

For a "double safety" purpose, I would like to use a heat bed power module add-on for the bed as well as the hotend. In case of a problem, I prefer to replace those cheap module instead of my entire board.

here is the module I'm talking about:
https://www.amazon.com/BIQU-Power-Module-Expansion-Printer/dp/B01HEQVQAK/ref=sr_1_12?dchild=1&keywords=3d+printer+pwm+mosfet&qid=1622841369&sr=8-12

As for the wiring, the main power pass through the power module and connect to the heat bed(or the hotend), and I have to wire the power module to the Duet2 through the "signal" wire (small white wire). As for the white wires, on the power module side, there is a + and -... On the Duet2, the + and - are identified on the board for the heatbed connectors, but there is no indication of + or - for the E0. I searched the internet for a diagram that would show such information, without success.

Anyone have any info or instruction or anything to help me ?

thanks for your help !

droftarts

@carl Polarity is marked on the back of the board. This is the back of my Duet 2 WiFi:

Edit: Personally I wouldn't bother with an external MOSFET (and that's all that is), if the bed heater isn't going to draw more than 15A, which is the limit of that part anyway. You don't have the protection of the fuse, either. Use a proper SSR if you're really concerned, but buy from reputable source, not ebay, too many fakes! And a hot end won't get near 6A, which is what the extruder heater outputs are rated at.

Ian

ReVeRb

@droftarts My hotend is 12V 70W, which is 5.833 amp. It's way too close to the max 6 amp for my taste. Is a SSR on the hotend could be necessary ?