FINDA turns N/A the moment it should load filament  

First check the connections are OK, loose plugs cause lots of intermittent issues.

If you have a multimeter check for continuity; has your wire work-hardenedand cracked..?

Cheerio,

cables are ok

just checked the wires with a multimeter.. no problem there.. also the precise timing of the failure indicates some software-related problem (I tried with filament 1 and 5..)

Next check your print-head filament sensor.  This is earlier in the call sequence...

Cheerio,

filament sensor is ok

I checked it by playing with it i.e. slightly bending the upper part of the extruder idler. Also playing around with the cable of the IR sensor has no impact on the correct working of the sensor. => The filament sensor of the extruder is working fine.

...but your FINDA remains intermittent..?

This usually indicates a faulty connection, perhaps a fracture in a wire that is flexing slightly but if you're sure continuity is OK then you had better contact Prusa support.

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Cheerio,

Found the problem

I found the issue. There is a small bump in the extruder idler..When trying to load filament, it turns very rapidly thus making for a very quick "1" for the sensor. This seems to have caused problems while loading. I fixed it by moving the upper mechanic part a little more from the IR sensor.

I figured it out with your help! 🙂 Thank you for guiding me through step by step!

Good to see you got it working again.

But does it still show N/A some times.

I had seen it on mine before and just checked again to make sure,

When starting and print the FINDA will show 0 when no filament is detected and N/A when the is filament detected. And will only turn to 1 when the filament sensor in the extruder turns to 1.

It does something similar during filament changed on a multi color print. I never looked into this as I think this is normal behavior  and my MMU works without any problems. 

same behaviour

I have the same behaviour, N/A when loading while not being detected in the extruder yet, 1 during the print. This was a little misleading during debugging..

btw: how comes I can't reply without always putting a new title like you guys..? 😀

I just hit the spacebar ones in the Title field.

Similar experience

My experience

Original F.I.N.D.A. behavior

With the original F.I.N.D.A. sensor (FS) the output states of 0 and 1 were as advertised in the manual during setup and testing. When a print was started the FS value changed from 0 to 1 and it’s LED turned off during filament load as the filament reached the F.I.N.D.A. As the filament passed the extruder filament sensor (EFS), its value shifted from 0 to 1 and the print was off to the races. The exact opposite behavior was observable during filament changes and unload.  I had to replace the original sensor because I started getting random filament changes and frequent loading errors.  Of course, this also happened when I first set the unit up, until I got the FS sensor position tuned in, but this new behavior was different. While observing sensor values, I noted the FS sensor value shifting to N/A in the middle of the print. This always initiated a filament change, or “an attention needed” error.  Finally, I discover that I could get the FS sensor value to shift between 0 to NA (or 1 to NA) by moving the cable at the top of the FS barrel. So I ordered a new FS sensor. What I got was a Super F.I.N.D.A.

Super F.I.N.D.A. behavior

With the Super F.I.N.D.A. sensor (SFS) the output states of 0 and 1 are as advertised, just like the original.  That’s the only thing that is the same. Once the bed leveling routine starts, the SFS value changes from 0 to N/A, but it’s LED stays on and the unit continues to initiate the filament loading sequence. When the filament triggers the SFS, the output still reads N/A, but now its LED turns off.  The filament continues to load to the extruder and as it passes the EFS, the EFS value changes from 0 to 1 and so does the SFS value.  During the print both the SFS and EFS values read 1.  During a filament change/unload, the EFS value goes to 0 as the filament is pulled out and the SFS values immediate shifts to N/A, but it’s LED remains off until the filament withdrawal pulls the filament clear of the SFS, and then the LED turns on.  I spent about an hour checking the wiring and testing the sensors behavior, but couldn’t get the new sensor to behave as the original sensor did.

I’ve completed 3 prints using the MMU2s with this new sensor and I’ve had no errors, but as mentioned in an earlier post, this is bewildering behavior, and should be included in the manuals or resolved by a software update.

RE: FINDA turns N/A the moment it should load filament

This is normal behavior and all it means is that the printer is unable to communicate with the MMU over the COM port because the MMU is not listening. The MMU and the I3MK3S+ communicate with each other via serial port and if the MMU does not respond right away then the main display on the printer will show FINDA is N/A. As soon as the MMU completes the current operation it will respond with the FINDA status.

The OP resolved their issue which was an incorrect calibration of the FINDA sensor, nothing to do with the N/A status display.