Rotating Magnetic Sensor - Keeps Pausing Printer

PetrKroupa

@alankilian, @dc42 - Today i will finish last big print. Then I will try to create some small GCODE (50 * 100mm) where the error will definitely show up. I'll test it and upload it here. We'll see what shows. So far, it seems that the error does not occur during the first layer.

PetrKroupa

@dc42 - One question, if the problem was somewhere on the HW side, the measured % value would be lower. Because the sensor simply turns less than the extruder. Correct?

However, this does not explain how a min -53% can happen. The extruder would have to create the filament.

Am I thinking right or am I completely out of it?

PetrKroupa

I finally figured out what was happening.

sensor.mp4

When the filament is slightly bent, the sensor restarts. Not always. But I managed to film it during manual extrusion. What is certain is that it cannot be wiring because nothing moves. It's weird that it only showed up with BETA6, but until then I didn't have a problem with it.

The question is why the sensor restarts.

alankilian

@petrkroupa said in Rotating Magnetic Sensor - Keeps Pausing Printer:

When the filament is slightly bent, the sensor restarts

OH! That's a good catch.

dc42

@petrkroupa is the AGC value reported by M591 consistently below 100 ?

PetrKroupa

@dc42 - Yes, it is solid somewhere between 91-93. I also verified that the spindle rotates freely and has no axial move.

I tried to tap the sensor in various ways, bend the connectors and twist it in every way. Strange....

dc42

@petrkroupa I think either there is a dodgy power connection somewhere, most likely in the wiring but possibly on the PCB itself; or something is causing the watchdog timer to time out. I can't see any reason in the firmware why the watchdog timer would time out, other than bad power or a transient causing the microcontroller to get into a bad state.

If you are sure that you can't provoke it or temporarily fix it by bending the wiring, then I suggest we replace the circuit board. Please email warranty@duet3d.com with a link to this thread.

PetrKroupa

@dc42 - I will make new wiring to sensor. I have order new sensor to my second printer. After it arrives, I will try found where is problem. If you are sure there is no FW reason to restart sensor intself, it must be somewhere in board/wiring. And since only the sensor is restarted and not tool board, the solution must be easy.

Waranty for that small and cheap thing it doesn't make sense to me. Thank you anyway.

I think we can close this thread. Thank you for your help.

T3P3Tony

@petrkroupa thanks for the diagnostic work. I came here to say i could not reproduce the problem with my test setup and your earlier print code - should have checked here again first!

Please do update this thread once you have tested your new board for the other printer.

CNCModeller

Hi All,
I'm still getting behaviour that I don't understand, I'm using the automated meta gcode for generating a PA calibration print. I've attached the gcode and some log files. The log file contains a readout of the filament sensor status triggered at each layer change.

Inspecting the print optimal PA seems to be at about 25mm, Pressure advance: 0.25

eventlog.txt

PATuning.g

The sensor is tripping out at about 40mm, but the measured sensitivity seems to start gradually reducing at about 20mm (0.2 PA).

Not sure if this data is useful, seems to me that the brim prints OK at slower speeds with measured calibration there being in line with settings. So IMO that seems correct.

The speeds don't vary after the first layer so the only thing that's changing is the PA as we go up the tower. And the first 20mm of Z seems OK in terms of measured filament usage. But starts to decrease after that. But then warns of too much filament?

As I said it doesn't make sense to me.

Hope this helps the bigger picture.

Cheers
Barry M

T3P3Tony

@cncmodeller you have your filament monitor configured as a pulse type not a magnetic type. If it is pulse type the the configured sensitivity looks wrong.

CNCModeller

@t3p3tony said in Rotating Magnetic Sensor - Keeps Pausing Printer:

@cncmodeller you have your filament monitor configured as a pulse type not a magnetic type. If it is pulse type the the configured sensitivity looks wrong.

Hi Tony.
It's a custom pulse sensor based on one of the output channels of a 600ppr (2400cpr) encoder and an old extruder gear system.

The measured values are consistent with the settings. It works well most of the time, but appears to glitch out every now and then.

Wasn't sure of this was an appropriate place to post but it seems relevant to this thread as the only thing changing is PA.

Hope that clarifies things.

Best regards
Barry M

T3P3Tony

@cncmodeller ahh ok I think its best to start a new thread on this.

CNCModeller

@t3p3tony will do

kroybal

@t3p3tony said in Rotating Magnetic Sensor - Keeps Pausing Printer:

@wouldstain please send a M591 D0 after the pause.

Checking my understanding here: does passing a M591 DX command display the data collected during an active print, following a pause?

I am experiencing similar issues "too little movement"...

I have a 3.x firmware and the DWC just gave me very basic description of the FM when I tried to do a M591 D1/2 command (I am not at the lab so I do not know off the top of my head which firmware I have/config settings).

But I recently installed two filament monitors to my IDEX direct drive printer. They are mounted on my custom designed/printed spool holders and false signal a pause after every 3.0mm reference length has been extruded.

My filament monitoring is very meat and potatoes default settings.

M591 D0 P3 C"io1.in" S1 R70:130 E3.0;			;Driver 0.0, rotating magnet, pinname, disabled, Low 70% High 130%, 3.0mm detection
M591 D1 P3 C"io2.in" S1 R70:130 E3.0;			;Driver 0.1, rotating magnet, pinname, disabled, Low 70% High 130%, 3.0mm detection

I guess I had some confusion on the A parameter, and the agc. Its not clear how to dial in an accurate parameter for that. Any tips?

PetrKroupa

@t3p3tony - The day before yesterday, the new ordered parts arrived. In the meantime, I made a completely new wiring to the MFM, re-soldered the connector (for safety) and the problem persisted.

After replacing the MFM control board, everything works without problems. Already the second 20h print and not a single fake filament alarm.

m591 d0
Duet3D rotating magnet filament monitor v3 on pin 121.io1.in, enabled, sensitivity 24.80mm/rev, allow 75% to 125%, check printing moves every 5.0mm, version 3, mag 133 agc 95, measured sensitivity 24.82mm/rev, min 96% max 104% over 31549.8mm

It really worked out for me to record printer on camera and see what happened after stop print. Just such an idea once someone solves a similarly strange problem.

Thanks to all for help.