IR Filamant sensor not switching in sensor state screen  

Re: IR Filamant sensor not switching in sensor state screen

Thank you for posting this. I had not turned on use of the filament sensor, but when I did, I discovered that mine did not work either.

You say your white wire is in the 2nd pin over from the left. I think that's the wrong place. The plug going to the board has five positions, and on my probe, the positions (left to right) are (1) white, (2) empty, (3) empty, (4) black, (5) red. You can confirm that here: https://d17kynu4zpq5hy.cloudfront.net/igi/prusa3d/vDJVYhT1YYZSy5Bu.huge

However, I found that my problem was different. I include the description here not to "hijack" your thread but to help others who might have the same symptom ("sensor not switching") as yours but caused by my problem.

I did not find any power supply voltage on the sensor board. I eventually traced this to the fact that my sensor was plugged into the board out of position, offset one increment to the right of where it should be. It is unfortunate that the design of the connector allows this misalignment. I had been so focused on using the lower row of pins that I didn't notice that it was possible to misalign the connector horizontally. I realigned the plug and now my sensor does report "0" when there is nothing blocking the path of the IR beam, and "1" when a tie-wrap is in the path.

And when assembled, my sensor does report "0" when no filament is present, and "1" when the filament is present. The status report is "live", i.e. it changes state when the sensor changes state, no need to click the knob to refresh the screen.

My firmware is 3.5.3 for the MK3S. (I don't have MMU and my 3 X 3 bed leveling works just fine, so I have no motivation to upgrade.)

The signal on the Einsy board is called "PK0" and it goes to physical pin 89 on the ATMega, which is labeled "ADC8 / PCINT 16".

Re: IR Filamant sensor not switching in sensor state screen

I think you are right. I got the upgrade kits for both my 2.5 and 3 and I apparently grabbed the cable for the 2.5s instead of the 3s, and when comparing, the the white wire is over one pin on the mk3s.

Appreciate the info. Who knows how long it would have taken me to catch that. Maybe when i went to do the 2.5s and noticed the cables are a different color.

Thanks again.

RE: IR Filamant sensor not switching in sensor state screen

Thanks! this post is a life saver! Worked like a charm.

RE: IR Filamant sensor not switching in sensor state screen

Hi,

Could somebody please explain the basics of how this particular MK3S/MMU2S IR Sensor works? It would help me resolve this seemingly simple IR Sensor Calibration step.

To my (lack of) knowledge, the source of the IR light, and the photo-sensitive element (diode) are typically on the same board. Well, in this case, the board (IR Sensor) is up there on the top of the "chimney", apparently completely detached from the filament flow chamber. If the board indeed contains the source of the IR light and the actual light sensor, I cannot see how the presence or absence of the filament can influence/trigger the state of the IR Sensor. I have taken the IR Sensor Holder apart several times to study it, looking for special holes/channels that would direct the light, yet after three days of trial and error I cannot understand how is this IR Sensor supposed to work, and how to correctly calibrate it to sense the presence or absence of the filament. The brief instructions in the MMU2S Handbook seem to be insufficient (it would be good to put this text online with the option for people to comment on each step, as that is typically helpful to others).

I read the forum posts related to the IR Sensor Calibration. I checked carefully, the connector of my IR Sensor is plugged in correctly into the socket on the electronics board. When I loosen the two screws and play a little with the exact position (and angle) of the "chimney", I can make the displayed status of the IR Sensor go from 0 to 1 and back, without the filament (or the tiny Allen key) present. But try as I may, I cannot get the status change dependent on the filament (Allen key) presence or absence. Maybe my IR Sensor board is defective? (handled it with utmost care by the edges only, as directed in the instructions)

Any suggestions on how to proceed, please? I am stuck, banging my head against the wall...

How is the presence/absence of the filament actually supposed to trigger the status of the IR Sensor? Where is the actual IR light source that the Sensor is to detect? How is the IR light supposed to be detected by the IR Sensor Board on top of the "chimney"?

Answers to these questions may probably help other people that find themselves facing this same similarly simple problem...

Thank you...

RE: IR Filamant sensor not switching in sensor state screen

the sensor ( mk3s version) is a simple photo interrupter sensor. it contains an IR source and detector separated by a small air gap. as installed on the printer with an MMU2 the sensor detects the movement of the long arm part of the extruder door. when the filament moves into the bondtech gears it moves the door ( and idler gear) which causes the arm to move into the gap  in the sensor. on the non-MMU2 printer the sensor is mounted in the top of the extruder and detects the movement of the filament detector ball assy as the filament enters the top of the extruder above the bondtech gears 

RE: IR Filamant sensor not switching in sensor state screen

After much reading and thinking, my understanding of the way how the IR Sensor works has evolved, this makes some sound logic now:

• When calibrated properly, the IR Sensor state is changed by the movement (opening/closing) of the Extruder Idler spring-hinged cover.
• The installation instructions fail to mention this, yet it is critical to understand how to calibrate the IR Sensor.
  I am probably not the only one who, working on over-simplified and due-to-that incomplete instructions, was reluctant to use a bit of force and push the tiny 1.5mm steel Allen key (simulating the 1.75mm filament) through the "teeth" of the Bondtech gear. But that is required, as that shifts the Idler Bondtech gear away from the stationary one, and moves the spring-hinged cover changing the light conditions, which in turn is detected by the IR Sensor.
  In the regular use, the driver Bondtech gear and the idler Bondtech gear "grab" the filament and push it into the PTFE tube a short distance below them. In those conditions, the tip of the filament is stiff and straight enough to get to the PTFE tube directly underneath the gears. But one cannot (easily) push a short piece of plastic filament through the Bondtech gears by hand, so for the IR Sensor calibration it is correctly recommended to use the 1.5mm Allen key (steel, obviously stiff strong enough). Obviously now, it is critical to actually push the metal Allen key through the "teeth" of the two Bondtech gears, thus shifting the idler away, which in turn slightly opens the idler cover, which changes the light conditions and this change is detected by the IR Sensor...

I believe the above is how the IR Sensor actually works. Any comments and/or corrections are most welcome.
(I have to wait a few days now for my Hotend Thermistor to arrive by UPS from Prusa3D. I was just about to verify my theory of how the IR Sensor actually works, when my Hotend Thermistor went crazy and started reporting some ridiculously high "temperatures", got MAXTEMP on the display, the sharp alarm sound went on. Now I have to fix that MAXTEMP alarm, before verifying my theory and eventually calibrating the IR Sensor...)

It is a practical experience that good beginner instructions can only be written by someone who is still a fresh newcomer to the subject, still actively learning. but (hopefully) guided by an expert. Those experts, people with lots of experience who know the subject very well typically skip over "obvious" explanations (like the one above about the functioning of the IR Sensor). Obvious to them, true, but not so obvious to someone out there in the field, myself included, who is stumbling through the steps of upgrading his MK3 printer for the very first time... Only a recent Beginner can think as a true Beginner...

RE: IR Filamant sensor not switching in sensor state screen

you have it right , i set up the sensor with the door tension screw disconnected so i can just apply finger pressure on the door and use an allen driver to move it without having a lot of pressure fighting me

RE: IR Filamant sensor not switching in sensor state screen

Thank you, David, you are confirming my thinking... I saw your reply after writing down my own understanding - thank you.

RE: IR Filamant sensor not switching in sensor state screen

also i modified my ir sensor board per the bunnyscience instructions to add a LED to the board to make monitoring it easy

( i'm used to doing surface mount soldering)

https://bunnyscience.dozuki.com/Guide/Bunny+and+Bear+(BNBSX)+MKS3+Geared+Extruder+Assembly/2?lang=en#s84

part of the BNBSX geared extruder mods

RE: IR Filamant sensor not switching in sensor state screen

im building a Bear Update printer with the BNBSX extruder and a MMU2S to go with my MK3S

https://www.thingiverse.com/thing:2808408 Bear Upgrade

https://www.thingiverse.com/thing:2823171 Y bearing holders

https://www.thingiverse.com/thing:3239428 BEAR reverse EISNY case with raspberry PI

https://www.thingiverse.com/thing:3450424   Bear Meanwell LRS-350 power supply mount

https://www.thingiverse.com/thing:3154293 BEAR update LCD cover - 2 color

https://www.thingiverse.com/thing:3610593 universal Carriage

https://www.thingiverse.com/thing:3626993 BNBSX extruder