Gmoccapy G54 Offsets

Now taking an interest in the G10 L2/L20 pair of Gcodes.
Cannot make sense of the Documentation against the machine display.
My current job is positioned with its G54 origin having x, y, z values -ve relative to Home.

Parameters #5221, #5222, #5223 are documented as the coordinate system Offsets for G54.
The parameters in the linuxcnc.var file correctly show the G54 origin with -ve values.

But, to set up the machine correctly, I have to swap the signs used with a G10 L2.

When Gmoccapy launches, before homing, the DRO shows the tool position with +ve values.
Then G10 L2 P1 with +ve values loads the DRO with -ve values (CORRECT for this job).

Then conventional Touch-Off and run the job.

Please, is my brained screwed, or is the Documentation misleading ?

John.

My brain is confused.
The sequence in the OP doesn't work.

The only reliable way I can set the machine up is to MDI a G0 with axes values per the Parameters (with the steppers off).

Still trying,
John.

Went back to Axis.
linuxcnc.var has Parameter #5221 = -238.
Ignoring y and z for this description.
Launch Axis, Display is:
- x238,
- G54 x-238.
This shows G54 x correctly as negative, ( whereas Gmoccapy shows G54 x as positive ).

No amount of Touching-Off, G10 L2, G10 L20, etc, by me gets to the final correct values for a job:
- x0,
- G54 x-238.

It appears G10 L2 and G10 L20 assume machine is actually Homed physically, and no amount of data entry can change that.

For jobs, I turn steppers Off, operate the machine controller to the measured table position, then Touch-Off, energize the steppers, and run the job.

Can anyone provide an alternative procedure to set-up the mill ?

John.

Thanks for the response.

Once my machine is set-up correctly, I successfully use multiple Offsets to do jobs on the table.

I started this investigation of G10 'assuming' that it was used to set-up the machine without having to physically move it to the Home position.

So far, that assumption has been demonstrated to be false.

What does one do if the machine cannot be physically moved to its Home position ?
For example, a large job mounted prior to machine start-up, or a vice.

Note: I simulate physical table movement at start-up by operating the controls with steppers Off to the position measured by ruler.

Tommy, thanks for taking the interest.

My aim was to simply improve my knowledge of some of the more exotic GCode.

As stated, my assumption on what G10 can do is incorrect.

My skill base has, however, improved because I can now use G10 for its intended use of setting up Offsets for multiple jobs.