Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 345)

Chapter 11
Coordinate Control
11-29
External Part Rotation can be executed before or after rotation of the work
coordinate system using the G68 command, see page 11-24. If a G68 is
programmed to rotate the current work coordinate system, an additional
rotation of coordinates result as shown in Figure 11.18.
Any work coordinate system rotation that is to be done using the external
rotation feature must be performed before program execution begins.
Program execution may not be interrupted to perform an external part
rotation. If you want to interrupt a program to perform an external part
rotation, the rotation does not become effective until the end of program
(M02 or M30) command is read, a control reset, or E-STOP reset is
performed.
Figure 11.18
External Part Rotation Followed by G68 Work Coordinate Rotation
Machine coordinate system
CENTER for External Part Rotation
Before
rotation
After External
rotation
Rotation center
for G68 Part Rotation
ANGLE for External
Part Rotation
VECTOR coordinates for
External Part Rotation
Work
coordinate
system
After External
and G68
rotation
12020-I
Important: This feature only simulates rotation of the machine coordinate
system for the purpose of establishing the preset work coordinate systems.
Software overtravels, programmable zones, and any other positioning
referenced on the machine coordinate system remain unaffected by this
rotation, but a program originally written within the limits can now be
outside these limits.