Rotating magnet filament monitor - frame errors?

themelle

The cable is about 50cm long and shielded. It contains four wires, and I used all of them by using a single wire for both GND and +3.3V, and combined two wires for SIGNAL. Could this have any negative influence leading to signal noise?

dc42

Which version Duet is it? The older ones have more filtering on the regular endstop inputs, which might be contributing to the framing errors. If so then you can connect the filament monitor to one of the endstop inputs on CONN_LCD instead.

When you get the "sensor not working" report, is there a regular pattern of red flashes from the LED on the filament monitor?

themelle

@dc42 Thanks for joining in

The printer is driven by a Duet Wifi 1.04 running RRF 2.04RC1.

When the "sensor not working" popup appears, the sensor does flash green all the time at around 1Hz. No red flashes as far a I can tell you.

dc42

Confirm that you are running firmware 2.03 or 2.04RC1 ?

themelle

This post is deleted!

themelle

@dc42
Sure, can confirm firmly

M122
=== Diagnostics ===
RepRapFirmware for Duet 2 WiFi/Ethernet version 2.04RC1 running on Duet WiFi 1.02 or later
[...]

themelle

As I need to get this issue sorted out in time I changed the sensor cable routing to be as far away from stepper wires as possible.

The test print stopped once with the infamous "sensor not working" message, but went otherwise fine.

Mid-print pause

M122
Extruder 0: pos 0.00, ok, measured sens 25.32mm/rev min 13% max 111% over 6476.1mm, errs: frame 10 parity 0 ovrun 0 pol 2 ovdue 0

M591 D0
Duet3D rotating magnet filament monitor v2 on input 3, disabled, sensitivity 24.80mm/rev, allow 70% to 130%, check every 3.0mm, current pos 0.0, measured sensitivity 25.32mm/rev, min 13% max 111% over 6476.1mm

After the print

M122
Extruder 0: pos 211.29, ok, measured sens 25.34mm/rev min 93% max 105% over 175.3mm, errs: frame 11 parity 0 ovrun 0 pol 2 ovdue 0

M591 D0
Duet3D rotating magnet filament monitor v2 on input 3, disabled, sensitivity 24.80mm/rev, allow 70% to 130%, check every 3.0mm, current pos 211.3, measured sensitivity 25.34mm/rev, min 93% max 105% over 175.3mm

Measured sensitivity seems pretty consistent throughout both runs runs, and the second run even seems to have produced what I would call "real" min/max extrusion percentages.

But the framing errors did not go away, and "pol" errors (What are those?) did show up.
So I assume it is basically not an issue with cross talk between sensor and stepper cables.

@dc42 @T3P3Tony
How can we further progress on this topic?

Thanks in advance!

dc42

When it reports "sensor not working", what pattern of flashes do you see on the sensor LED?

themelle

@dc42 The LED flashes green at around 1Hz.

themelle

@dc42 Any clues yet? Anything that I can try, measure, test?

dc42

Green flashes at 1Hz are normal when there is no filament motion AFAIR.

In case it's a wiring issue, can you see the red endstop LED on the Duet flashing in time with the green LED on the filament monitor?

themelle

@dc42 Thanks for your input.
I'll try to verify this, probably on friday. Will come back to you with results

themelle

@dc42 Got around to give it another try. When the sensor flashes, the end stop LED does not light up at all.

themelle

@dc42 Did another test - strange thing is the LED now flashes red at around 1Hz when the "sensor not working" popup appears.
Also, the popup appeared tithes time for the first time immediately after starting the print from DWC, but way before any moves of the print head or extruder, as heating up had barely begun.

dc42

@themelle, if the sensor LED flashes only red then it is reporting an error condition back to the Duet.

If it gives several red flashes, pauses, then repeats, it is flashing an error code (count the number of flashes). When it does this, the Duet will record framing errors.

themelle

This post is deleted!

themelle

@dc42, I know, there are some error codes listed over there (https://duet3d.dozuki.com/Wiki/Duet3dFilamentMonitor_RotatingMagnetVersion).
But the red flashing is not paused in between - it is flashing at around 1Hz continuously ...

themelle

@dc42, is there anything else I can do for now or should I contact Filastruder to issue a warranty return?

themelle

@dc42 @T3P3Tony
The replacement filament monitor arrived today - thanks for the really fast and painless swap!

Just installed, gave it a quick go ...

no more "Sensor not working" messages
M591 D0 reports quite usable data
- Duet3D rotating magnet filament monitor v2 on input 3, disabled, sensitivity 25.33mm/rev, allow 85% to 115%, check every 3.0mm, current pos 14.8, measured sensitivity 25.21mm/rev, min 90% max 110% over 1252.5mm
M122reports no frame errors anymore
- Extruder 0: pos 14.77, ok, measured sens 25.21mm/rev min 90% max 110% over 1252.5mm, errs: frame 0 parity 0 ovrun 0 pol 1 ovdue 0

Will do some more tests in the coming days, but those are by far the best results I was ever able to get!

Thanks to both the teams of Filastruder and Duet3D for your great support!
Much appreciated!