How to stop spindle 3 mm before end of the line ?

Thank you for answers and help. I think distance to go would be a good solution but I don't know how to do that. I am using Linuxcnc since one week so understand me please. If anybady knows how to write such hal componet help me please

Thanks in adwance
wojtek

I think you would use comp (see man comp.9)

You will need to add things like this to your hal file .
This would send an on/off signal for any movement. You will need to add something to over ride it when you don't want it on (like positioning moves) or to enable it when you do want it on.

I still think that the velocity pin would be a better option because, with distance to go, if you have a complex shape or line (poly line) 100mm long made up of 2mm segments, your pump will never turn on. If you are sure you would never use code like that then it should work fine. Using the velocity pin the number and size of segments in a line would not matter. You would just need to calculate the best rate to shut off at. What are your feed and acceleration rates? Maybe your accel is to high to make a velocity shut off practical?

There may be a better way to do this though. How are the 3-d printer people doing it?

[Oops duh, forgot to count from 0 naming comp.N, changed 1 to 0]

The latest 3DP thing using machineikit seems to be "velocity extrusion"
which seems better for "painting" type applications

If there is significant lag in the "spindle", extruder, glue gun, whatever
it might be nice to delay the motion with a delay comp (n samples delay),
so the velocity can have a bit of lookahead

'comp.1.in1' not found


loadrt comp count=1
setp comp.1.in1 3.000
net ink_off_float comp.1.in0 => motion.distance-to-go
net ink_off_bit parport.0.pin-16-out => comp.1.out

The first comp is comp.0

comp.1.in0 not found ,

You will probably need to use the and2 component to combine the distance to go signal with your current pump on signal.

linuxcnc.org/docs/html/man/man9/and2.9.html

Connect the comp.1.out pin and what every you had connected to your parallel port output pin, to the two and2 inputs. Then connect the output from the and2 to the parallel port pin.

Then when ever you have the pump commanded on, and distance to go is greater than 3mm the pump would run. If either of those two conditions are not met the pump would be off.

(just don't pause the machine during a drawing move, I am pretty sure your pump will keep running, another argument for using the velocity pin)

Thanks a lot for help. I have change comp.1 into comp.0. Now there is : PIN parport.0.pin-16-out was al ready linked to signal 'spindle-on'