Laser Filament Monitor not working with another filament sensor



  • Hey!
    I am using both an inductive sensor with stealball (MMU2 clone) and the laser filament sensor. I am getting weird errors from the laser monitor and I don't see whats wrong... Maybe a bug?

    My setup:

    MMU2 with 3 axis (U,V,W), V is the drive shaft and is connected to E1 on Duet, the U,W are on DueX2. V is using the inductive sensor to check for successful filament loading after a tool change. The inductive sensor is connected to endstop E1.

    The main extruder E0 is being monitored by the laser sensor, connected to endstop E0.

    When printing, I want to use the inductive sensor as a filament run out switch on E0 as well. That way I can retract the filament and load a new one.

    When I print anything, I often get "Extruder 0 reports too little movement" and "Extruder 0 reports sensor not working". Especially the later one seems weird to me.

    Thanks in advance for any help!


  • administrators

    hi @nikscha does the sensor work ok when you are just using it on a single filament print (so the MMU elements are not effecting what is happening?)



  • I just disassembled the laser monitor and there was some dust on it 😐
    I am running the monitor on its own right now and so far everything seems fine. So probably not a bug just my fault.

    But regardless, is there a way to use both the inductive sensor and the laser monitor on the same extruder at the same time? Maybe I can wire the inductive sensor into the filament run-out switch on the laser-m? Or I can define a virtual axis and assign the laser-m to it and map it to somehow?


  • administrators

    @nikscha if the inductive sensor can be made to emulate a simple switch then it could be wired to the SW header on the LFM.



  • @T3P3Tony no clue whether thats possible 😅
    how does the behaviour of the laser-m change if it is wired to a switch? I need it to be able to act like an endstop and also to be able to trigger a trigger. Would that work?



  • @T3P3Tony I did some testing to make sure I understand whats going on and there is still some weird behavior. Ignoring all the MMU parts (I commented everything out of the config file that was related to the mmu), the Laser sensor is still behaving weirdly. Most of the time it is working as it should but if I start a second print without powercyling the duet wifi I get the error "Extruder 0 reports sensor not working". This error gets displayed a few times during the calibration, after the calibration the print continues just fine for the most part. Sometimes there are more errors displayed later on during the print but this is only the case in about 20 % of prints.


  • administrators

    @nikscha said in Laser Filament Monitor not working with another filament sensor:

    @T3P3Tony I did some testing to make sure I understand whats going on and there is still some weird behavior. Ignoring all the MMU parts (I commented everything out of the config file that was related to the mmu), the Laser sensor is still behaving weirdly. Most of the time it is working as it should but if I start a second print without powercyling the duet wifi I get the error "Extruder 0 reports sensor not working". This error gets displayed a few times during the calibration, after the calibration the print continues just fine for the most part. Sometimes there are more errors displayed later on during the print but this is only the case in about 20 % of prints.

    Can you use M591 to disable the sensor at the start of calibration, and enable it again afterwards?



  • @dc42 disabling the sensor during the calibration worked. But I still get occasional "Extruder 0 reports sensor not working" errors during printing. Last print was 4h in which the error appeared 2 times. Could it be the wiring? Is there a way to debug this issue further, maybe some log files i can check?


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