Yaskawa MotionWorks+ Windows Software - Manual (Page 218)

Appendix C MW+ Camming 101 MotionWorks+™
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Disengaging
Disengaging is similar in concept to engaging. During this process, mState_Camming is
set to four. The master may not be at a location to disengage at the time the CAM disen-
gage is executed. The “External Position” property of the CAM block specifies the master
position at which the slave must stop following the master. The same window size is used
to determine when it is OK to disengage.
On the scan when it is determined that the master is in the window, a switch takes place,
and instead of using the actual master value for the cam look up table, the system ladder
uses the value or variable entered in the CAM disengage block’s “External Position” prop-
erty as if it is the actual master position during that scan. This is done because slight errors
in the slave position could result if on the last scan the master is not perfectly at the disen-
gage position, and the cam table is designed such that the slave is not exactly at it’s
intended resting position when disengagement occurs.
This phenomenon would most likely appear in applications that engage & disengage fre-
quently. (A perceived drift would result if the slave were repeatedly disengaged at a
slightly different location than the engage point.)