Rockwell Automation GMLC Reference Manual - Manual (Page 313)

Publication GMLC-5.2 - November 1999
276 Motion Blocks
See the System Variables chapter of this manual for more information on
these variables. Note that the cam is not automatically disabled when the
master axis moves out of the range defined by the master cam table. See
Disable PCAM and Stop Motion sections for more information on
disabling and stopping position-lock cams.
Position-lock cams are fully interpolated. If the current master axis
position does not correspond exactly with a point in the specified profile,
the motion controller uses linear interpolation to calculate the slave axis
position between the two closest points. This provides for the smoothest
possible motion. Also, when a Jog Axis or Move Axis block is
subsequently used on the axis, the position-lock cam remains active. This
lets you superimpose time-lock cam motions on electronic gearing
motion, thereby creating complex synchronization.
See the Axis Locked and Axis Done Conditions chapter of this manual for
a complete discussion of the operation of these status conditions when a
move, jog, or time-lock cam is superimposed on position-lock cam
motion.
Virtual Master Axes
Because AxisLink virtual axes are functionally equivalent to physical
Master Only axes, they can be used as the master axis for position-lock
cams. However, only one of the two available virtual axes can be enabled
at one time—enabling one virtual axis automatically disables the other
virtual axis if it had previously been enabled. Thus, you must first enable
an AxisLink virtual axis, with a previous Virtual Axis Control block,
before it can be used as the master axis for a position-lock cam. See
Virtual Axis Control Block in the AxisLink Block chapter for information
on enabling virtual axes.
Position-Lock Cams and the Imaginary Axis
You can use the imaginary axis as either the master or the slave axis for
position-lock cams. However, because the imaginary axis’ output is its
command position—it has no actual position—only Command is
available for selection.