Endstop help

rs4race

Im using a LJ12A3-4-Z/BX inductive sensor for my z max endstop. I have it wired to an always on fan pin, and the signal thru a diode to the z endstop connector. It lights up when triggered and the light by the z axis driver lights up as well. Theres no change when m119 is sent.

Am I missing something? I've tried setting m574 z2 s1 and s0 but there is no change when the sensor is triggered.

dc42

What type of diode are you using? Others have found that an ordinary silicon diode doesn't pull the endstop pin low enough and you need to use a Schottky diode.

rs4race

I am using "FAIRCHILD SEMICONDUCTOR 1N4148TA DIODE, ULTRAFAST RECOVERY, 300mA, 100V, DO-204AH"
I beleive I bought this based off info here but it was a long time ago. I read somewhere else last night to hook sensor ground and signal to the endstop pins. I currently have ground and power hooked to an always on fan channel. Could this be it?

darkorbz

I'm using a LJ12A3-4-Z/BY (PNP with a diode similar to yours), on my printer:
; Endstops
M574 X1 Y1 S0 ; Set active low endstops
M574 Z1 S0 ; Set endstops controlled by probe
M558 P3 H5 F120 T6000 ; Set Z probe type to modulated and the dive height + speeds
G31 P250 X16 Y30 Z0.5 ; Set Z probe trigger value, offset and trigger height

dc42

@rs4race:

I am using "FAIRCHILD SEMICONDUCTOR 1N4148TA DIODE, ULTRAFAST RECOVERY, 300mA, 100V, DO-204AH"
I beleive I bought this based off info here but it was a long time ago. I read somewhere else last night to hook sensor ground and signal to the endstop pins. I currently have ground and power hooked to an always on fan channel. Could this be it?

Try a Schottky diode instead as recommended at https://duet3d.com/wiki/Connecting_a_Z_probe#NPN_output_normally-open_inductive_or_capacitive_sensor.

rs4race

Thanks again! The Schottky diode works.

To sum things up. The 1N4148TA diode didnt work.
I Wired the LJ12A3-4-Z/BX inductive sensor as follows:
Power wires to always on fan channel (24V)
Blue is Ground
Brown is 24V

Signal wire to Z stop pin of Z stop Connector
Black - (Cathode) Schottky Diode - Z stop pin

In config I set

M574 Z2 S0 ; z axis homes in positive direction active low

And my Z home file

G91 ; Relative positioning
G1 Z200 F420 S1 ; Move quickly to endstop
G1 Z-2 ; Back off of endstop
G1 Z3 F60 S1 ; Move slowly to endstop
G92 Z186.5 ; Set Z axis position
G90 ; Absolute positioning

I hope this will help anyone with the same question.