Homing an axis

[vmax549]

Do I understand it correctly that there is no way to Home an axis from Gcode or Mcodes ?? How does the Home axis button work ?

(;-) TP

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[Tbkahuna]

It would be helpful to know what you are trying to accomplish.

Do you want to re-reference one axis of the machine? Do you just want to move to the limit switch location?

[vmax549]

I wish to send the axis to the home switch and set machine coord to zero. Home the axis.

(;-) TP

[Tbkahuna]

Just wondering. I can tell you what I have done that might be related. I ran a program with XYZ and A moves in it. I programmed the A axis (rotary table) from a starting point of A=0. The program didn't end on A=0, so rather than wind or rewind the A axis to 0 for the next part, I just did a G92 A0 to set the A position to 0, regardless of how many rotations it had gone through. That position was now A=0, so going to A360 was exactly one rotation. I don't remember all the details of the G92, but that is what came to mind when I read your question.

Maybe you could just do G0 x-100 to go in the -x direction until the limit switch is hit, then G92 x=0. (or whichever axis direction and limit you want to zero).

[vmax549]

That would be just resetting the work coord to zero and has nothing to do with homing the axis . But thanks for the thought..

(;-) TP

[gerritv]

I think what you are looking for is G53? https://gcodetutor.com/fanuc-trainin...0-g53-g54.html

[rodw]

When you home an axis in Linuxcnc (which Tormach uses), homing usually searches for a home switch. It is possible to set your config to have an axis to home immediate which means the current position becomes the home position.

[vmax549]

Yes that is true BUT that is not what I am looking for. I am looking for a process to REF_HOME the B and C axis from a GCODE call similar to how every one else does it with G28.1 .

have found a Python call " ref_axis(4)" That indicates it can refhome an axis . I will try a remap to see if it can do it from there.

(;-) TP

[mountaindew]

Yes that is true BUT that is not what I am looking for. I am looking for a process to REF_HOME the B and C axis from a GCODE call similar to how every one else does it with G28.1 .

have found a Python call " ref_axis(4)" That indicates it can refhome an axis . I will try a remap to see if it can do it from there.

(;-) TP

I would suspect Linux cnc /Tormach Path Pilot developers follow g-code industry standards as close as possible. That does not stop them from hiding, changing or disabling behaviors or codes. But I dont think your going to find what you want unless its a standard g-code.

[rodw]

Yes that is true BUT that is not what I am looking for. I am looking for a process to REF_HOME the B and C axis from a GCODE call similar to how every one else does it with G28.1 .

have found a Python call " ref_axis(4)" That indicates it can refhome an axis . I will try a remap to see if it can do it from there.

(;-) TP

Why don't you use G28.1 similar to how anyone else does it?
G Codes

[kstrauss]

I believe that G28.1 is a best efforts move to the PREVIOUS home position rather than going to the CURRENT home position. Consider the difference in results if steps have been lost on a mill without absolute encoders or if the home switches were repositioned.

[vmax549]

IN PathPilot G28.1 assigns the current location to return to. It could be anywhere. Calling G28 then simply returns to that location. Same with the G30/G30.1 .

Having a REFHOME gcode is very handy when working with rotary axis that can do both continuous and indexed moves. When in continuous rotation like a spindle then there is NO home position. When you change back to index mode then it is required that you refhome the Axis so it know where it is at in 3d space.. Most usefull in mill/turn like applications.

Linuxcnc has several Gcodes that are not Gcode standard codes (;-) G38(g31) and G10(g68/69). Polar mode (G15/16).

[rodw]

I just had a play on my Linuxcnc plasma cutter. Homed machine, jogged to some random position and touched off to my laser pointer using G54 as I usually do. Now at X0,Y0.
G28 returned to the home switch position
Typing G0 X0 Y0 had no affect I was expecting it to go back to my touch off position (X0,Y0)
Jogged to some random position, entered G28.1 and jogged away.
G28 returned me to that position


Its a long time since I have used G28. I stopped using it.

From what I understand the expected usage is to use G54 offsets (well any from G54 to G59.3)
See: G Codes

Life is much easier now I use G54. Try it and see how you go

[vmax549]

HI Rod, I think you are missing teh point. I do not want to just return to a point I want to refHome the axis back to the home switch. That will in turn reset the"Machine" home position not the WORK position.

(;-) TP

[rodw]

You might be able to use the halui home and unhome pins
HALUI
and use the digital output pins (M62-M65) to set them
Looks like you also would need to select the axis (halui.axis.joint.N.select)

halui is designed to program a user console so its possible they pins you need are in use so you could unlinkp them and use an or2 component so either source worked.