Allen-Bradley 1756-HYD02 User Manual page 229

Configure Camming
Important: The cam profile generator monitors the master axis based on the absolute position reference system in
effect before the redefine position operation.
This process only occurs if the position reference of the master axis is redefined with a Motion Redefine
Position (MRP) instruction after the MAPC instruction executes but before the lock condition is satisfied.
The Position Cam Status bit of the Motion Status word for specified slave axis is
set. This process occurs when the absolute position of the master axis passes the
specified Master Lock Position in the specified direction. Slave axis motion is then
initiated according to the specified cam profile starting at the specified Cam Lock
Position of the cam profile.
From this point on, only the incremental change in the master axis position
determines the corresponding slave axis position from the defined cam profile.
This condition is important for applications where the master axis is a rotary axis
because the position cam is then unaffected by the position unwind process.
When the master axis moves out of the range that the cam profile defines, if
Execution Mode is Once, the following occur:
•
It clears the Position Cam Lock Status
•
It clears the Position Cam Status bits of the Motion Status word
This Motion Status bit condition indicates that the cam process has completed.
This fact is also reflected in the bit leg behavior of the associated MAPC
instruction, PC bit set, and IP bit clear.
The master axis can change direction and the slave axis reverses accordingly. This
process occurs after position cam motion is started when the master axis passes the
specified Master Lock Position in either the Forward Only or Reverse Only
direction.
If an MAPC instruction is executed on a slave axis that is actively position
camming, an Illegal Dynamic Change error is generated (error code 23). However,
this error does not occur if the Execution Schedule is Pending.
Rockwell Automation Publication MOTION-UM002F-EN-P - February 2018
Chapter 5
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