Rockwell Automation Publication MOTION-UM002E-EN-P - June 2016 117
Configure Camming Chapter 8
To maintain the velocities and accelerations of the scaled profile approximately
equal to the values of the unscaled profile, the Time Scaling and Distance
Scaling values must be equal. For example, if the Distance Scaling value of a
profile is 2, the Time Scaling value must also be 2. This requirement is to
maintain approximately equal velocities and accelerations during execution of
the scaled time cam.
Cam Execution Modes
Cam execution modes determine if the cam profile is executed only one time or
repeatedly. You must configure the Execution Mode parameter on an MAPC
or MATC instruction.
Execution Schedule
The Execution Schedule parameter controls the execution of an instruction.
You must configure the Execution Schedule parameter on an MAPC or
MATC instruction. The Execution Schedule selections are different
depending on which instruction, that is, the MAPC instruction or the MATC
instruction, you are using.
MAPC Instruction
The Execution Schedule parameter selections are the following:
•Immediate
•Pending
•Forward Only
IMPORTANT If you decrease the Time Scaling value or increase the Distance Scaling of a
time cam, it increases the required velocities and accelerations of the profile.
This action can cause a motion fault if the capabilities of the drive system are
exceeded.
Table 14 - Execution Mode Descriptions
Execution Mode Description
Once Cam motion of slave axis starts only when the master axis moves into the range defined
by the start and end points of the cam profile. When the master axis moves beyond the
defined range, cam motion on the slave axis stops and the Process Complete bit is set.
Slave motion does not resume if the master axis moves back into the cam profile range.
Continuous Once started, the cam profile is executed indefinitely. In this mode, the master and slave
positions are unwound when the position of the master axis moves outside the profile
range. This unwinding causes the cam profile to repeat. This feature is useful in rotary
applications where it is necessary that the cam position runs continuously in a rotary or
reciprocating fashion.
Persistent
(1)
(1) This selection is only available on the MAPC instruction.
The cam motion of the slave axis proceeds only when the master axis moves within the
range defined by the start and end points of the cam profile. When the master axis moves
beyond the range of the profile, cam motion on the slave axis stops. Cam motion only
resumes when the master moves back into the profile range specified by the start and end
points.
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