Rockwell Automation 8520 9/Series CNC Integration Maintenance Manual Documentation Set - Manual (Page 703)

Integrating a Split Axis with Deskew
Section 14B
14B-9
If the markers are close to zero degrees or 180 degrees away when the
home switch is tripped, it is difficult to predict which way each servo will
rotate to find the closest marker (see Figure 14B.5). This can create the
undesirable situation in which the master and slave servos move in
opposite directions to find the nearest marker. The worst case situation
would be if the markers were close to 180 degrees away from the home
switch and moved in opposite directions to find the nearest marker.
Figure 14B.5
Repeatable Motion to Encoder Marker
Home limit switch
YES
NO
Off On
Control will consistently select this
as nearest encoder marker
Control may pick either of these
as nearest encoder marker depending
on home limit switch transition
Correct by relocating
home limit switch
Home limit switch
“ON”to “OFF”
transition range
Master
Slave
Master
Slave
A slight misalignment
between master and slave
encoder markers is to be
expected
16. Home the split axis. This may be performed using either manual or
automatic (G28) homing.
17. Fine tune the home position of each servo. If a small amount of
misalignment exists between the two servos, adjustments can be
made using the Home Calibration AMP parameter. Adjust the home
calibration value for the servo with its marker closest to the home
limit switch after homing. Home Calibration can adjust each servo’s
home position relative to its encoder marker. It does not adjust
master and slave servo home positions relative to each other.