Magnetic Filament Monitor skips values
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Hi,
We're having trouble with the magnetic filament monitor. At random times the min and/or max values are going way out of boundaries. On the last test we've been printing for 3 hours at a min of 98% and max of 103% which is perfect but then all of the sudden the min % goes to -2 and a filament error would've been thrown (if it were enabled, for the test we've disabled it). We see this issue at all of the tested sensors, we've already tried at least 5 of them, all with the same errors.
To investigate this I've set up a camera on the filament monitor and made a script to read out the 'M591 D0' command every 500ms which gives the min and max values.
That's where I noticed something strange. I've setup the monitor to check every 10mm. Filament monitor configured like this:
M591 D0 S0 P3 C"io6.in" R10:200 L25.66 E10.0
Format is:
Timestamp ; mm/rev ; min% ; max% ; extrusion length
You can see 2 readouts per second, and it's always 10mm difference
Until 2022-02-21 14:32:41, that's where the -2% kicks in and the length of the extrusion goes from 47713.9 to 47735.1. Which means it skipped the check of 47723? That could explain the -2% but the question is why it did this.The filament monitor is very tightly above the extruder with basically zero slack. The cable we use to connect the filament sensor is a shielded USB cable (quite long, +-1m but from the M122 report not a lot of parity errors I think). Firmware used: 3.3 (stable)
Anyone any idea on why this happens?
2022-02-21 14:32:30.216658;25.85;98;103;47683.6 2022-02-21 14:32:30.738172;25.85;98;103;47693.7 2022-02-21 14:32:31.264376;25.85;98;103;47693.7 2022-02-21 14:32:31.781113;25.85;98;103;47693.7 2022-02-21 14:32:32.304583;25.85;98;103;47693.7 2022-02-21 14:32:32.823373;25.85;98;103;47693.7 2022-02-21 14:32:33.339471;25.85;98;103;47703.9 2022-02-21 14:32:33.858594;25.85;98;103;47703.9 2022-02-21 14:32:34.377199;25.85;98;103;47703.9 2022-02-21 14:32:34.891098;25.85;98;103;47703.9 2022-02-21 14:32:35.410627;25.85;98;103;47703.9 2022-02-21 14:32:35.933013;25.85;98;103;47713.9 2022-02-21 14:32:36.451486;25.85;98;103;47713.9 2022-02-21 14:32:36.973117;25.85;98;103;47713.9 2022-02-21 14:32:37.497339;25.85;98;103;47713.9 2022-02-21 14:32:38.025809;25.85;98;103;47713.9 2022-02-21 14:32:38.543906;25.85;98;103;47713.9 2022-02-21 14:32:39.069231;25.85;98;103;47713.9 2022-02-21 14:32:39.591714;25.85;98;103;47713.9 2022-02-21 14:32:40.119249;25.85;98;103;47713.9 2022-02-21 14:32:40.636024;25.85;98;103;47713.9 2022-02-21 14:32:41.148661;25.86;-2;103;47735.1. <---- Goes to -2% 2022-02-21 14:32:41.663060;25.86;-2;103;47735.1 2022-02-21 14:32:42.181884;25.86;-2;103;47735.1 2022-02-21 14:32:42.707009;25.86;-2;103;47735.1 2022-02-21 14:32:43.226921;25.86;-2;103;47735.1 2022-02-21 14:32:43.747173;25.86;-2;103;47745.2 2022-02-21 14:32:44.261284;25.86;-2;103;47745.2 2022-02-21 14:32:44.778342;25.86;-2;103;47745.2 2022-02-21 14:32:45.304965;25.86;-2;103;47745.2 2022-02-21 14:32:45.824641;25.86;-2;103;47745.2 2022-02-21 14:32:46.342921;25.86;-2;103;47755.3 2022-02-21 14:32:46.871972;25.86;-2;103;47755.3 2022-02-21 14:32:47.388141;25.86;-2;103;47755.3 2022-02-21 14:32:47.906232;25.86;-2;103;47755.3
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@christophe There is a bugfix in the 3.4 release candidate that fixes possible race conditions and that short extruder moves are sometimes missed by filament sensors. If possible you could try it out and see if it solves your problems
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@snimax said in Magnetic Filament Monitor skips values:
@christophe There is a bugfix in the 3.4 release candidate that fixes possible race conditions and that short extruder moves are sometimes missed by filament sensors. If possible you could try it out and see if it solves your problems
I remember trying on a 3.4 beta (don't know which one anymore)
But now testing on 3.4.0rc1Thanks for your response
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@snimax said in Magnetic Filament Monitor skips values:
@christophe There is a bugfix in the 3.4 release candidate that fixes possible race conditions and that short extruder moves are sometimes missed by filament sensors. If possible you could try it out and see if it solves your problems
@Snimax With the new firmware Duet 3 Mini 5+ 3.4.0rc1 (2022-02-09) it lasted a lot longer (about 150m of filament) but then the min went down to 9%, and again shortly after that with a second test.
The polling is every 500ms, so the logs seems to be right. But it changes from 2991 to 3006. Which is a difference of 15mm instead of the defined 5mm
2022-02-23 15:24:02.832525 Rev: 25.9 Min% 97 Max% 104 Dist 2986.5 2022-02-23 15:24:03.345354 Rev: 25.9 Min% 97 Max% 104 Dist 2991.5 2022-02-23 15:24:03.869892 Rev: 25.9 Min% 97 Max% 104 Dist 2991.5 2022-02-23 15:24:04.388842 Rev: 25.9 Min% 97 Max% 104 Dist 2991.5 2022-02-23 15:24:04.904781 Rev: 25.9 Min% 97 Max% 104 Dist 2991.5 2022-02-23 15:24:05.422710 Rev: 25.9 Min% 97 Max% 104 Dist 2991.5 2022-02-23 15:24:05.938432 Rev: 25.9 Min% 97 Max% 104 Dist 2991.5 2022-02-23 15:24:06.460237 Rev: 25.9 Min% 97 Max% 104 Dist 2991.5 2022-02-23 15:24:06.982769 Rev: 25.9 Min% 97 Max% 104 Dist 2991.5 2022-02-23 15:24:07.500814 Rev: 26.1 Min% 9 Max% 105 Dist 3006.5 <-- error occurs 2022-02-23 15:24:08.016133 Rev: 26.1 Min% 9 Max% 105 Dist 3006.5 2022-02-23 15:24:08.532569 Rev: 26.1 Min% 9 Max% 105 Dist 3006.5 2022-02-23 15:24:09.047566 Rev: 26.1 Min% 9 Max% 105 Dist 3006.5 2022-02-23 15:24:09.568569 Rev: 26.1 Min% 9 Max% 105 Dist 3006.5 2022-02-23 15:24:10.084863 Rev: 26.1 Min% 9 Max% 105 Dist 3006.5 2022-02-23 15:24:10.602402 Rev: 26.1 Min% 9 Max% 105 Dist 3006.5 2022-02-23 15:24:11.124012 Rev: 26.1 Min% 9 Max% 105 Dist 3011.7 2022-02-23 15:24:11.641503 Rev: 26.1 Min% 9 Max% 105 Dist 3011.7