Rockwell Automation 8520-ARM2 9/Series CNC AMP Reference Manual Documentation Set - Manual (Page 101)

Axis Parameters
Chapter 4
4-17
Deskew Axes (Splits)
The split axis feature (which allows more than one servo to position one
physical axis) is available for dual processing systems. You can assign
only one split axes to each process. Additionally, if you choose to share a
split axis between processes, the system is restricted to having only one
split.
Important: On dual processing controls the slave servos must be the last
servos AMPed in it’s selected process. If the split axis is shared, the slave
servos must be the last servos AMPed on the system in both processes (last
axes on the system before spindles).
A split axis (single axis driven by two or more servos) can be configured
as a shared axis. If you are going to change processes for a split axis,
changing the process for the master servo (in PAL) changes the process for
all servos that make up the split axis. You must configure all servos of a
split axis as either shared or not shared, you cannot mix within the split
group. You can not change the process for individual servos of a split axis.
END OF CHAPTER