Yaskawa MotionWorks+ Windows Software - Manual (Page 214)

Appendix C MW+ Camming 101 MotionWorks+™
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5. How does camming work?
The Master
First, camming requires that the master position be modularized to the external encoder
machine cycle, which must also match the last master point in the table. The system lad-
der modularizes the master automatically when camming is engaged. A modularized
position can also be selected in the system properties, so position of the master
(mPosition_External) will look like this:
This modularized value is used as a pointer to the cam table to find the slave position.
However, an important conversion happens first. The modularized master value is scaled
by the last value found in the cam table. The conversion looks like this:
This conversion can be the source of trouble if the external encoder’s machine cycle and
the last master position are not the same. The purpose is to convert the master in counts to
“table units” if they are not already the same. In the above example, the machine cycle is
100 counts, but the last master position in the table is 360. The conversion takes place,
and 47/100 = 169/360, or about 50% through the cycle. If the cam master were pro-
grammed in counts, then the conversion would be 1:1. This same feature can be a benefit
if the application can benefit from stretching or shrinking the profile by changing
sMachineCycle_External.
Time
Position
Modularized Master in
counts.
Value used as
pointer to cam table