Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 359)

Coordinate Control
Chapter 13
13-7
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 a external part
rotation. If an attempt is made to interrupt a program to perform an
external part rotation the rotation will not become effective until the end of
program (M02 or M30) command is read, a control reset, or E-STOP reset
is performed.
Figure 13.5
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
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 will remain unaffected by
this rotation, but a program originally written within the limits can now be
outside these limits.