Page
Chapter: 6
Section:
PROGRAMMING
7
REFERENCE SYSTEMS
6.3.3. COORDINATE PRESET AND ZERO OFFSETS
With this CNC it is possible to apply zero offsets in order to use the coordinates relative
to the part's blueprint without having to modify the coordinates of the point on the part
when editing a program.
A "Zero Offset" is the distance between the part zero and the Machine Reference Zero
(home).
The zero offset may be applied as follows:
*
In the jog mode, by presetting a coordinate value or "0".
*
By means of function G92 (coordinate preset) where the CNC takes the programmed
values as new axis position values (coordinates).
*
By loading the zero offset table (G51.....G60) and then selecting one of them (T
function). The CNC takes as new part zero the point located at the distance indicated
by the table from Machine Reference Zero (home).
6.3.3.1 COORDINATE PRESET (G92)
When applying a zero offset by means of function G92, the CNC does not move
the axes. It assumes the coordinates programmed after G92 as the new axis position
values.
If machine parameters "P100(8)=0", "P100(7)=0", the CNC stores internally the distance
from the new Part Zero to Home.
On certain applications as cyclic rollers, the accumulated distance from home after
many continuous presets may overflow the CNC memory.
In this type of applications, it is possible to use G92 as a "coordinate setting" (versus
presetting), (P100(8)=1, P100(7)=1, where the CNC selects a new Part Zero without
storing its distance from home.
The programming format in either case is:
G92 X — Y —
Example:
N125 G90 X50 Y40 Positioning at P0
N126 G92 X0
Y0
Presetting P0 as Part Zero
N127 G91 X30
Programming according to blue-
print
N128
X20 Y20
N129
X-20 Y20
N130
X-30
N131
Y-40
N132 M30
Attention:
A block containing G92 may not contain any other G code.
Function G92 is incompatible with G51, G52, G53, G54, G55, G56, G57,
G58, G59 and G60.
