System variable for current Z machine position

Hello

I am writing a subprogram to suit my machine and I need to get the current Z machine position.

Looking at:
linuxcnc.org/docs/html/gcode/overview.html, I would use:
#<_z> - Return current machine Z coordinate. Same as #5422.

I tested using 5022 or 5422, but both return the actual relative position, not the machine position that I am looking for.

Would this be a bug or am I looking at the wrong variable?
I am using a custom 2.6 pre

Thank you

Hi

I think it is a case of imprecise phraseology

5420-5428
Current Position including all offsets and in the current program units for X, Y, Z, A, B, C, U, V & W, volatile.

5422 returns the current relative position in the active co-ordinate system I believe, so it definately does not return machine position despite
what this says

#<_z> - Return current machine Z coordinate. Same as #5422.

I have never needed to access actual machine position from gcode and was rather surprised to find there was no set of parameters for it,
unless I too cannot see them.

You can get machine position programmatically from halui.axis.n.pos-commanded (float, out) - Commanded axis position in machine coordinates
but that does not assist you much.

One way would be to touch off one of the co-ordinate systems to 0,0,0 at home and then it will mirror machine position and you can use that

regards

Thank you,

I will wait a bit more to see if there is anyone using it (maybe it already exists). If not I will think about possible turnarounds but yours is quite good: "One way would be to touch off one of the co-ordinate systems to 0,0,0 at home and then it will mirror machine position and you can use that"

Take a look here...
linuxcnc.org/docs/2.5/html/gcode/overvie...umbered_parameters_a

Rick G

Yes, my original post was related with that list, so no more relevant information there. Thank you anyway.

It would take a whole lot of if/thens but how about a subroutine to check #5210 and #5220 to check what offsets are active.
Then subtracting the correct parameter #5211 through #5219 or #5221 through #5390 from #5420 - #5428.

what do you think?

I believe Chris used something like this to find X Y when looking for the center of a circle..

Or as Alan suggested if you know what coordinate system you are going to work in work with the parameter and the offset.

Rick G

andypugh wrote:

emcPT wrote:

I tested using 5022 or 5422, but both return the actual relative position, not the machine position that I am looking for.

A roundabout way to get machine absolute position is to perform a G30.1 then read #5183

www.linuxcnc.org/docs/html/gcode/gcode.html#sec:G30-G30_1

This was the most straight forward method, so I believe I will use it.
Thank you