Rockwell Automation 8520-ARM2 9/Series CNC AMP Reference Manual Documentation Set - Manual (Page 608)

Dual Axis Parameters
Chapter 34
34-2
The control can support five dual axis groups. A dual axis group consists
of two or more grouped axes coupled through AMP and commanded by a
master axis name. The master axis name is used by the part programmer
or operator when commanding the dual axis group in part programs or for
jog moves.
Each axis that makes up a dual axis group is controlled by a separate
positioning command from the servo module. This dual group command
is based on the move generated by the control when the master axis is
commanded to a position. Each axis in the group must still have its own
position and velocity feedback device which is monitored and used to
correct any following error independently for each axis.
Positioning Dual Group Members Independently
If desired, certain axes in a dual group may be disabled (or parked).
Parked axes are not positioned when a request is made to move the dual
axis group. Parking an axis in a dual group is accomplished through PAL.
Refer to your PAL reference manual for more information.
If it is necessary to position members of a dual axis individually without
parking any axes in the group, the PAL axis mover may be used. This
feature ignores any link between axes in a dual group. Even axes that are
parked may be positioned using the PAL axis mover.
Dual process controls also offer the ability to decouple dual axis groups.
This allows you to determine if axes can be programmed independently as
well as in their dual group without requiring any axes be parked.
Per Axis versus Per Group
All axes that make up a dual axis reach end-point at the same time. This
requires that all axes that make up a dual axis group share the same
feedrate parameters, acc/dec ramps, and other axes specific data for the
group. All axes in a dual axis group take on the characteristics of the worst
case axis. For example, the slowest “maximum cutting feedrate” of one of
the axes is used as the “maximum cutting feedrate” for all axes in the dual
group. This is the case even if the worst case axis is parked at the time of
the motion.
This same worst case characteristic remains when the dual group is
decoupled. When decoupled the individual axes that made up the dual
group are still bounded by the slowest axis:
Acc/Dec Ramp
velocity step
rapid feedrate
max cutting feedrate