Re: Re: G code Examples

Alan

These values are stored in the *.var file that is specified in the *.ini
file that you use. The emc.var file is the default and is man readable.
If you do not use the one in the latest release this file is self
commented.

-----snipped from emc.var 9-25-00 release-----
Axes offsets for G92
5211 0.000000
5212 0.000000
5213 0.000000

Coordinate system for G54-- the default used at start
5221 0.000000
5222 0.000000
5223 0.000000

Coordinate system for G55
5241 0.000000
5242 0.000000
5243 0.000000
-----end of snip-----

I don't use g92 myself so I can't say what effect the values in this place
have on the next startup. Instead I use the numbered coordinate systems so
I have several available to me -- and I always know where they are!

But Tom explains g92 in his interpreter manual.

-----snipped from NIST manual-----
To make the current point have the coordinates you want (without motion),
program G92 X- Y- Z- A- B- C- , where the axis words contain the axis
numbers you want. All axis words are optional, except that at least one
must be used. If an axis word is not used for a given axis, the coordinate
on that axis of the current point is not changed. It is an error if: all
axis words are omitted.

When G92 is executed, the origin of the currently active coordinate
system moves. To do this, origin offsets are calculated so that the
coordinates of the current point with respect to the moved origin are as
specified on the line containing the G92. In addition, parameters 5211 to
5216 are set to the X, Y, Z, A, B, and C-axis offsets. The offset for an
axis is the amount the origin must be moved so that the coordinate of the
controlled point on the axis has the specified value.

Here is an example. Suppose the current point is at X=4 in the currently
specified coordinate system and the current X-axis offset is zero, then G92
x7 sets the X-axis offset to -3, sets parameter 5211 to -3, and causes the
X-coordinate of the current point to be 7.

The axis offsets are always used when motion is specified in absolute
distance mode using any of the nine coordinate systems (those designated by
G54 - G59.3). Thus all nine coordinate systems are affected by G92.

Being in incremental distance mode has no effect on the action of G92.

Non-zero offsets may be already be in effect when the G92 is called. If
this is the case, the new value of each offset is A+B, where A is what the
offset would be if the old offset were zero, and B is the old offset. For
example, after the previous example, the X-value of the current point is 7.
If G92 x9 is then programmed, the new X-axis offset is -5, which is
calculated by [[7-9] + -3].

To reset axis offsets to zero, program G92.1 or G92.2. G92.1 sets
parameters 5211 to 5216 to zero, whereas G92.2 leaves their current values
alone.

To set the axis offset values to the values given in parameters 5211 to
5216, program G92.3.

You can set axis offsets in one program and use the same offsets in
another program. Program G92 in the first program. This will set parameters
5211 to 5216. Do not use G92.1 in the remainder of the first program. The
parameter values will be saved when the first program exits and restored
when the second one starts up. Use G92.3 near the beginning of the second
program. That will restore the offsets saved in the first program. If other
programs are to run between the the program that sets the offsets and the
one that restores them, make a copy of the parameter file written by the
first program and use it as the parameter file for the second program.
-----end of NIST snip-----

You can read all about it in the handbook at linuxcnc.org

Ray

From: Alan Marconett KM6VV <KM6VV@...>

As I understand it, G92 "sets" the controller's coordinates to that
specified? And something is saved to a file, for the next time the
machine is run? I'm not clear on what gets remembered. MaxNC remembers
the last coordinates the machine was at (when restarted), is that part
of G92's function?

I was looking for a "Gcode" instruction to set the current location for
MY program! Thanks!