Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 479)

Dual Axis Operation
Chapter 19
19-5
When using automatic homing (G28), the axes must be homed one at a
time. This is accomplished by parking all other axes in the dual axis group
except the axis that is to be homed and requesting the AMP assigned
master axis name be homed in the G28 block. Once homed, that axis
should be parked, the next axis to be homed should be unparked, and the
homing procedure repeated. Refer to chapter 14 for details on how to
request an automatic home operation (G28).
Homing Axes Simultaneously
This method allows a request for all axes in the dual group to be homed at
the same time. This does not mean that all axes reach home at the same
time. Keep in mind that the system installer may define different feedrates
and different home positions for each axis in the dual group.
With proper PAL programming, the system installer can configure all axes
in the dual axis group to home when the request is made using the master
axis name. If this homing method is used, all unparked axes will home
together. Refer to chapter 4 for details on how to request a manual home
operation and chapter 14 on how to request an automatic home operation
(G28).
Axes in a dual axis group can be positioned using any of the normal
programming or manual motion operations. To position a dual axis, only
the master axis name can be requested. Requests to position a dual axis
can be made in manual, automatic, or MDI mode.
For absolute and incremental moves, regardless of the start-point, each axis
in the dual group reaches the requested position (or travel the requested
distance) at the same time. For absolute moves, this means the individual
axis feedrates may be modified, depending on the distance each axis must
travel from start to end of the requested move.
The system installer can assign different maximum cutting, external decel,
and rapid feedrate limitations for each axis in a dual axis group. The
control uses the slowest feedrate for each of these features from any axis in
the dual axis group.
19.1.3
Programming a Dual Axis