6HC to 3HC ground loop?
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Sorry, I can't find anything with a search. I seem to recall there being the possibility of blowing up boards by strapping the GPIO on a 6HC and a 3HC to the same ground reference? Can anyone confirm one way or the other please?
Could you avoid this by running a 2nd 6HC as an extension board (child to a parent 6HC), powered off of the same 5V supply?
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I'm not sure what you're asking. How are you trying to wire the 6HC and 3HC?
Have you seen the 3HC info and wiring diagrams?
https://duet3d.dozuki.com/Wiki/Duet_3_Expansion_Hardware_Overview#Section_Power_distribution
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@phaedrux Yes, thank you. The Duet3 GPIO suffers badly from noise on long cable runs so I am driving the endstops with 24V via optocouplers. I have 12 axes and the opto interface boards come in 4 or 8 channels. This doesn't match the 6HC or 3HC and they have separate ground references (being powered from a 5V and a 24V supply respectively), so I expect to use a separate 4ch for each 3HC and an 8ch or 2 of 4ch interface boards with a 6HC. However, if I could bridge the ground plane between different Duet boards then I could get away with fewer opto interface boards.
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I have received this as a reply: "This is almost never an issue, especially if the 3HC and the 6HC have their ground connected together, even if they are powered by different supplies."
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@phaedrux OK, thanks. So strap the 5v and 24v ground together on the 6HC and carry on.
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@theolodian said in 6HC to 3HC ground loop?:
5v and 24v ground together on the 6HC
The grounds on the 6HC are already connected together
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@t3p3tony So the ground reference across the 6HC and any extension boards should be the same as long as you are connecting them all to the same 24v supply. Thanks for confirming.
