Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 411)

Axis Motion
Chapter 14
14-35
If an axis included in the G30 block has not been homed, block execution
will stop and the following error message will appear:
“MACHINE HOME REQUIRED OR G28”
Important: When the control executes a G28 or G30 block it temporarily
removes any tool offsets and cutter compensation during the axis move to
the intermediate point. The offsets and/or cutter compensation are
automatically re-activated during the first block containing axis motion
following the G28 or G30 unless that block is a G29 block. If a G29
follows, the offsets and/or cutter compensation remain deactivated on the
way to the intermediate point and are reactivated when the axis moves
from the intermediate point to the point indicated in the G29 block.
The G04 command delays the execution of the next data block. Dwell
length is specified in either of two types.
Seconds
Number of spindle revolutions
The type used is normally dependant on the feedrate mode (G93, G94 or
G95) active at the time. The type can also be permanently fixed to
“seconds,” regardless of G93, G94 or G95 mode, by setting the proper
AMP parameter.
14.4
Dwell (G04)