Can I use multiple filament sensors on one extruder axis?



  • Hey!
    I am building a MMU2 based filament changer.
    I want to have two filament presence sensors, one close to the extruder and one on the MMU2 unit. Maybe even a rotating magnet sensor close to the extruder. (How) can I configure multiple filament (presence) sensors for one extruder axis?



  • If you don't need both active at the same time you can reconfigure RRF on the fly to swap between them.



  • @bearer Not quite. "Normal operation" would be:

    • the magnet sensor close to the extruder monitoring filament flow
    • the sensor at the MMU monitoring filament presence.

    when changing the filament, the magnet sensor is not necessary, i just need one presence sensor at the hotend and one at the mmu. Here i can just define endstops that use the sensor pin or i check the status of the sensor using the object model.

    So now I need to find a way to have the flow monitor running independent of the presence monitor at the mmu, while both can pause the print.



  • @nikscha said in Can I use multiple filament sensors on one extruder axis?:

    while both can pause the print.

    if you have enough inputs you can configure one sensor as a trigger that runs pause, and the other that works as a regular filament sensor; and shift the configuration around as needed.

    but I don't see why you'd need both to cause a pause - if it runs out of filament both will trigger sooner or later no?



  • @bearer Good idea with the trigger!

    but I don't see why you'd need both to cause a pause - if it runs out of filament both will trigger sooner or later no?

    I want to have a system that continues printing even when one filament is empty, for that to work I need to sense the "end" when its close to the MMU so I can retract it all the way out.



  • then you don't need both to pause; simply assign it as an enstop and move until the endstop triggers? more than one way to skin a cat.

    I think there should be an example of a duet running a mmu if you go looking you may find some inspiration


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