Rockwell Automation GMLC Reference Manual - Manual (Page 239)

Publication GMLC-5.2 - November 1999
202 Motion Blocks
Incremental Moves with Gearing
You can use a Gear Axes block while an incremental move is in progress
on the slave axis. The gearing motions are superimposed on the move
profile. Conversely, you can use an incremental move block while gearing
is enabled to cause a similar effect. This allows you to accomplish many
complex move profiles and sophisticated synchronization. Superimposing
an incremental move on top of electronic gearing is particularly useful to
accomplish phase advance/retard control.
Incremental Moves on Rotary Axes
When an axis is configured for rotary operation, the motion controller
handles incremental moves in the same way as with linear axes, except
that when the axis position exceeds the unwind parameter, the axis
position is unwound. In this way, axis position is never greater than the
unwind value, and never less than zero.
The specified distance is interpreted trigonometrically and may be
positive or negative and can be greater than the unwind value. When the
distance is greater than the unwind value, the axis moves through more
than one revolution before stopping.
Phase Shift Moves
You can use a Phase Shift move to shift a position-lock cam profile
relative to its master axis position, thereby shifting the timing of the
profile. In this way, the Phase Shift Move you can change the
synchronization between the slave and master axes of a position-lock cam
on the fly. This is analogous to phase shifting a mechanical cam by
rotating it on its shaft. Phase Shift moves should only be used on the slave
axis of a position-lock cam while the position-lock cam is executing. See
the Position Lock Cam section in this manual for more information.
When you select Phase Shift, the currently executing position-lock cam
profile shifts, relative to the position of its master axis, the specified
distance at the specified speed using the specified acceleration and
deceleration settings, as shown in the following diagram.