Rockwell Automation Publication MOTION-UM002E-EN-P - June 2016 123
Configure Camming Chapter 8
Figure 61 - Pending Cam Execution
By executing the position cam profile as a Pending cam profile while the
current profile is still executing, the appropriate cam profile parameters are
configured ahead of time. This condition makes the transition from the
current profile to the pending profile seamless. Synchronization between the
master and slave axes is maintained. To make sure of smooth motion across the
transition, however, the profiles must be designed as follows. No position,
velocity, or acceleration discontinuities can exist between the end of the
current profile and the start of the new one. This process is done by using the
Logix Designer Cam Profile Editor.
Once a pending position cam instruction has been executed, the new cam
profile takes effect automatically (and becomes the current profile). This
process occurs when the master axis passes through either the start or end point
of the current profile. If the current cam is configured to execute once, the new
profile is initiated at the completion of the current cam profile. The PC bit of
the currently active instruction (either MAPC or MATC) is also set.
If the current cam is configured to execute continuously, the new profile is
initiated at the completion of the current pass through the current cam profile.
The IP bit of the currently active instruction is also cleared. The motion
controller tracks the master axis position or time, depending on which
instruction is used. The slave axis position relative to the first profile at the time
MAPC Instruction
MATC Instruction
Slave Axis
Position
Master Axis Position
Accel Profile Run Profile Decel Profile
Slave Axis
Position
Master Axis Time
Accel Profile Run Profile Decel Profile
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