@dc42 What current does the duet draw at the 3.3V Z probe input?

@hurzhurz yeah i think you got me right. that could actually work too.
In what unit would i put the trigger point value (behind the P of G32 Pxxx)?
Or is it just 0?
I think german would be easier, but english would be better for the others here

@JoergS5 Sorry, don't have any solutions for that

@hurzhurz yes these modes are possible to set, but the problem is that the voltage stays after the set point is reached.
For example 0-5V: above 0 the voltage is 0V, the closer it gets to 0 the voltage rises (the point from which is the voltage rises can be set too) : 10mm 0V; 5mm 2,5V 0mm 5V.
If the distance gets negative the voltage stays 5V
So I thought it would be better that the voltage above and below 0 would change, so that it doesn't get too deep and still thinks it's at 0 distance

Not sure if I was able to explain it understandably...

The idea with the digital output and the octocoupler sounds possible, will try that!

I've been trying out a bit and it seemed to kinda work. I'm getting a signal in.
Can't work on it till probably next week, cause the z-axis clutch broke.

Another thing is, that the laser is giving 0V if the distance is 0. if it's more than 0 the voltage rises till 5V and stays there and same with negative, falling to -5V.
As the z probe input works with 3.3V i was thinking about using a resistor to ground and also in series a schottky diode for the negative voltage (thanks for that info @dc42).
I'm just not sure about what resistor and what diode to use. Any suggestions?

What current does the input draw at 3.3V?

maybe this schottky diode:
https://www.conrad.de/de/p/panjit-schottky-diode-gleichrichter-1n5817-do-41-20-v-einzeln-1304858.html

@hurzhurz yes that one looks kinda similar. And that principle would work?

@themelle @dc42 Do you know what would happen if I feed negative voltage (-3.3V) into the Z probe input?

@dc42 I didn't quite get what you meant, sorry

what would happen if you feed a negative voltage (-3,3V) into the Duet Z probe input?

@dc42 said in laser as z probe:

I looked into laser distance sensors several months ago, especially as there are some low cost ones around now. The main problem is that you need extremely high resolution, repeatability and temperature stability.

Let's start from first principles. The speed of light in vacuum or air is very close to 1 foot per nanosecond. So each nanosecond of measured time is 300mm of distance there and back, or 150mm one-way. Therefore each picosecond represents 150 microns of distance. If we take 30 microns as the required repeatability of Z probing (and some types of Z probe are better than this), this means that your measurement system needs a resolution and stability of about 200 femtoseconds. Even if you can achieve this resolution, it's most unlikely that you will achieve this stability.

but i'm using the il1500 to read the measurement of the laser (il100). i can give out an analog high signal if a preset distance is reached. Wouldn't it be possible to to read the analog signal with the duet?
should workk like a switch then or not?

I'm based in Germany.
Got an arduino uno flying around here, so could use that if necessary

I changed from the il300 to an il100, cause of the range of the laser
Also uploading the datasheets and the manuals of both

Page 5 of the il1500 manual: As far as I can see, the il1500 can give out an analog output from 0 to 5V. I can also set a low and max point, inbetween its giving out a go signal.
Maybe I could use one of them

AS_107023_IL_IM_96M13643_GB_1109-3a.pdf
IL-100_Datasheet.pdf

I can upload the datasheets also in german/other languages if that helps

i will be able to get the datasheet tomorrow, to see what output i can get from the laser.
what type of output would i need to communicate with the duet?

Hello

I'm building a selfmade 3d printer.
It's a cartesian printer, with y axis moving the bed and x and dual z the extruder.
Board: Duet ethernet 1.21 (currently working on implementing 2.03)

My question is, if it'd be possible to use a laser as the z probe instead of a normal z probe.

I'm using the il-300 with the il-1500 by keyence. it's already showing me the distance between the laser and the bed, but i don't know how to wire the laser to the board and how to change the firmware.

Any help would be much appreciated.

Thanks!