Rockwell Automation 8520 9/Series CNC Lathe - Manual (Page 344)

Coordinate Control
Chapter 13
13-2
Example 13.1
Altering Planes for Parallel Axes
Assuming the system installer has made the following assignments in AMP:
G18 -- the ZX plane.
U axis -- parallel to Z axis
V axis -- parallel to X axis
Program block Plane selected Axis Motion
G18; selects ZX plane None
G18 U0; selects UX plane U axis moves to zero
G18 V0; selects ZV plane V axis moves to zero
G18 U0V0; selects UV plane U & V axes move to zero
This manual assumes your system installer has selected the G18 plane to
be activated when an end-of-program block is read (M02 or M30), a
control or E-STOP reset is performed, or power to the control is turned off.
Important: Any axis word in a block with plane select G-codes (G17,
G18, G19) causes axis motion on that axis. If no value is specified with
that axis word, the control assumes a value of zero or generates an error
depending on how your system is AMPed.
There are two methods for programming axis positioning commands:
absolute positioning
incremental positioning.
In the absolute mode, coordinates are referenced from the zero point of the
active coordinate system. Absolute mode is established by programming a
G90.
G90X40.Z20.;
In the above block, the control moves the axes to a position X40, Z20 as
referenced on the active coordinate system.
G90 is a modal G-code, and it remains active until cancelled by a G91.
In the incremental mode, coordinates are referenced from the current axis
position. Programming a G91 establishes an incremental mode.
G91X40.Z20.;
13.2
Absolute/Incremental Modes
(G90, G91)