NPN sensor problem

[dc42]

@petr-k if it's definitely a NPN NO sensor, then this command should work:

M558 P5 C"^!zprobe.in" H5 F120 T6000

unless the senor has high leakage current. If that's the case then you might need to add a pullup resistor (e.g. 10K) between the sensor output and +3.3V or +5V. But I've not heard of this happening before.

Are you certain that it isn't a PNP output sensor?

[Petr K]

@dc42 This is writes on sensor LJ20A3-10-Z/BX. Ok I will try pull-up, thanks.

[Petr K]

@dc42 pullup did nothing

[Petr K]

@fcwilt said in NPN sensor problem:

M558 P5 C"^!zprobe.in" H5 F120 T6000

Z probe value 1000, when triggered value is 0

[fcwilt]

@petr-k said in NPN sensor problem:

@fcwilt said in NPN sensor problem:

M558 P5 C"^!zprobe.in" H5 F120 T6000

Z probe value 1000, when triggered value is 0

Was that with the ! character or without?

Frederick

[Petr K]

@fcwilt M558 P5 C"^zprobe.in" H5 F120 T6000

[fcwilt]

@petr-k said in NPN sensor problem:

@fcwilt M558 P5 C"^zprobe.in" H5 F120 T6000

Well then it should work with the ! unless the the output voltage of the sensor simply isn't meeting the logic levels needed of the input.

What is the forward voltage drop of that diode?

Did you try it without the diode?

As I recall the logic 0 voltage level for the input is appx 0.8 volts. It's possible the combination of the drop across the NPN transistor in the sensor and the diode fails to meet that logic 0 level.

Frederick

[Petr K]

@fcwilt I try it without diode too, but it was the same, nothing changed.

[fcwilt]

@petr-k said in NPN sensor problem:

@fcwilt I try it without diode too, but it was the same, nothing changed.

Do you have a way to measure the voltage at the input to the board to verify the low (sensor triggered) and high (sensor not triggered) voltage levels

Frederick

[Phaedrux]

@petr-k said in NPN sensor problem:

M584 M584 X0 Y1 Z2:4 E3 ; set drive mapping

You have M584 twice on that line.

[Petr K]

@fcwilt

[dc42]

@petr-k if you have a multimeter then as @fcwilt suggested, you should measure the voltage between the IN pin and GND pins of the Z Probe connector. You should get:

• With the sensor not connected: nearly 3.3V (and DWC should report the Z probe reading as 0). If you don't read 3.3V then most likely your M558 command is wrong.
• With the sensor connected but not triggered: same (except that if the sensor includes a pullup resistor, you may get a higher voltage than 3.3V)
• With the sensor connected and triggered: about 0.2V if you don't use the diode, or 0.5V if you do.

Edit: in your photo it looks as though you may be using 2 diodes connected in series.

[Petr K]

@dc42

sensor connected, not triggered - 3.0V
sensor connected, triggered - 0V
sensor disconnected, not triggered - 0V
sensor disconnected, triggered - 1,5 V

All with diode.

My soldering looks like a second diode

[Petr K]

G31 X35 Y-4 Z0 P500 was the problem, I had two parameters P (P0 and P500), now works great

[Petr K]

@petr-k And P≠0