202 Rockwell Automation Publication MOTION-RM002H-EN-P-February 2018
is typically executed continuously. To stop the axis, the operating profile can be
smoothly blended into a deceleration profile such that the axis stops at a known
location as shown below.
By executing the time cam profile as a Pending cam profile while the current
profile is still executing, the appropriate cam profile parameters are set up ahead of
time. This makes the transition from the current profile to the pending profile
seamless – synchronization between the master time and slave axes position is
maintained. To ensure smooth motion across the transition, however, the profiles
must be designed such that no position, velocity, or acceleration discontinuities
exist between the end of the current profile and the start of the new one. This is
done using the Cam Profile Editor.
Once a pending time cam instruction has been executed, the new cam profile takes
effect automatically (and becomes the current profile) when cam time passes
through the end of the current profile. If the current cam is configured to execute
once, the new profile is initiated at the completion of the pass through the current
cam profile and the PC bit of the currently active MATC instruction is 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 and the IP bit
of the currently active MATC instruction is cleared. The motion controller
keeps track of time and the axis positions relative to the first profile at the time of
the change and uses this information to maintain synchronization between the
profiles.
If the Execution Schedule of an MATC instruction is set to Immediate and a time
cam profile is currently in process, the MATC instruction generates an Illegal
Dynamic Change error.
If an Execution Schedule of Pending is selected without a corresponding time cam
profile in progress, the MATC instruction executes but no camming motion
occurs until another MATC instruction with a non-pending Execution Schedule
is initiated. This allows pending cam profiles to be preloaded prior to executing
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