Wiring suggestions with 3hc expansion boards
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I'm moving my quad from duet 2 to duet 3 with expansions. Any considerations of what I should try to keep on the main board, and what is fine to be on the expansions boards. I remember earlier firmware versions didn't support input shaping on expansions. I have 16 steppers and I need to connect. For example, I am thinking I can put the 4 z axis steppers on the expansion boards. Probably the 4 extruder steppers can go on the expansion boards too...
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@kazolar There is a different stepper power budget on the main board vs. the expansion boards. You can also use a main board as an expansion board.
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@theolodian the power usage shouldn't be an issue. My steppers are well below the max rating. I'm asking if there are some limitations or preferences of what should be on the main board vs the expansion boards. If all the same, I'll just place the expansion boards closer to where the wire runs are to minimize wiring I need to replace.
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@kazolar with firmware 3.4.0 there are few restrictions, however my preference would be to connect the X and Y motors to the main board. You say it is a "quad", do you mean IDEXY? If so then I suggest you connect the U and V motors to the main board too. Extruders can be connected to expansion boards, so can Z motors if you run RRF 3.4.
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@dc42 I have 2 gantries. There 2 "y" steppers on each gantry which home and ensure the gantry is not skewed, as they each can home independently, my current setup is with logic gates, so duet 2 doesn't know there are 2 steppers per gantry, now with no hard limit of 14 steppers, I will be getting rid of the custom logic circuit and have the duet 3 control both steppers on the y gantries. So essentially there are 8 steppers in the xy motion system...2 more than on the main board. My thought was to keep y0, y1, and u0, and u1 steppers on the main board, that's 4. And 2 others will do one gantry x and v, then I need to have one of the expansion boards do the 2nd gantry a and w (2nd set of x axis ). Quad z will be on expansion and extruders will be on expansion. With 4 expansion boards I have plenty of options.
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@kazolar I'm not sure what the current restrictions are but historically they were mostly about having endstops on different boards to motors, and temperature sensors on different boards to heaters. So as long as you connect endstops to the same board as the motors they will be used with, and sensors on the same board as the heaters they will be used with, you ought to be safe (but check the docs to see what the current restrictions are). I prefer to have the boards as close to the motors that they control as it simplifies the wiring. For that reason, I have X,Y and Z on an expansion board, U,V,A and B on the main board and three extruders on each of two further expansion boards (6 extruders in total).
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@deckingman thank you. I was hoping not to have to replace current wiring, so having the connection be made close to where cable chains exit will be best, sounds like I'll be able to do that. Almost done printing my expansion enclosures. Will start migrating the wiring next week. Would also be nice to configure control board fans to be MCU temperature dependent, probably ok to have all fans in each enclosure be linked of the main MCU temperature.
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@kazolar Ref cooling the control boards, what I did on my old Duet Ethernet +Duex 5 setup was to attach thermistors to a couple of the driver chips with a small blob of epoxy adhesive, and use these to thermostatically ramp cooling fans (IE, fan speed increased with driver chip temperature). With my Duet3 setup, I've found that additional board cooling isn't necessary despite some of the motors being NEMA 23s @2.4 Amps. But my boards are all vertically mounted and "open" rather than enclosed so your mileage may vary.
