So, slightly similar to https://forum.duet3d.com/topic/7365/hotend-crashing-into-bed-during-auto-calibration, but I have P1 already set, and it is not always this issue happens..
I have Duet 2 ethernet, v2.02 fw, Cartisian 1m3 printer, with IR sensor (with SMDs) near hotend... occasionally when doing mesh calibration the sensor does not trigger on the Duet, whilst the LED does light up on the IR board - I have revised also https://miscsolutions.wordpress.com/mini-height-sensor-board/, "Troubleshooting, LED turns on/off to indicate triggering, but the printer firmware does not recognise whether or not it is triggered", but it is not clear how I may correct pullup resister values if they would be too high, as I am getting the expected 4 flashes on power up, and am using a Duet anyway...
To add complication, although this has been a very occasion issue with PLA (no heated chamber), curiously, when pressing "Auto Bed Compensation" it generally failed at the same point, if it failed (probing stops as no trigger detected, head rams against bed to -4, when my axis limit is -1!), but when using "Run Mesh Grid Compensation" it fails less often, and generally at a different point! As far as I can observe, "Auto" runs a Home first, whilst "Run mesh" does not, it just starts (as long as machine was already homed).. both give a height map once/when finished.
I would also like to learn how to configure a "backup" endstop - the Z-endstop works fine, is magnetic, so when the probe fails to trigger no damage is done to the endstop, but I would like that, if the probe fails, the Z-endstop trigger stops any further Z move, as, this morning, when doing a G30 in the center of the bed, a one-off probe that up until now has always worked first time, today did fail, and went a lot more than -4mm, bending the heatbreak a lot... either that or that the machine respects the axis min of Z-1 that is in my config when doing a Z probe...
And now to make things worse (but possibly can id the issue as well?)! :
This printer is (supposedly) ready for ABS, being contained in a metal box all the motors and rails, however when set to only 60ºC the heated chamber, the bed height now varies just over 2mm higher, and the bed surface itself suffers some bending, to the extent that it is now necessary to do a new grid compensation, however now the issue is much more repetitive, so much that cannot finish a complete probe - until I remember that troubleshooting, and also that resisters increase resistance with heat, and that the Duet is in a place where it is also heating up (not so much, somewhat) - and placing a fan directed at Duet now permits finishing the Bed Compensation - but does not get rid of completely the issue as still occasionally fails - with todays spectacular fail of the G30!
So.. if this issue is from a pullup resister on the Duet being borderline slightly too high (?), I remember that for Duet 0.6/0.85 there was a way of indicating the thermistor resister value - any way this can be indicated in the config? Or any idea what else could be the issue here?
And how can I enforce axis min so that they are not exceeded? Or perform a stop when the Z-endstop is triggered to avoid such exaggerated bed movements in negative..?
Any opinions would be appreciated!