Lenze PLC Designer PLC Designer (R3-1) - Manual (Page 581)

L-force | PLC Designer
General Editors
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DMS 4.1 EN 03/2011 TD29 579
Choose the non-periodic mode for avoiding jumps:
MasterAbsolute := TRUE;
SlaveAbsolute := FALSE;
CAM(x1, CAM1, PERIODIC:=FALSE); This call evaluates the CAM at master position x1, which
is smaller than the end position of the range of CAM1.
So, CAM1 is evaluated in the usual way resulting in Point
1 for the slave position.
CAM(x2, CAM1, PERIODIC:=FALSE); When the module is called for the next time, the master
position x2 has exceeded the end position of CAM1
(indicated by the green dashed line and equal to the
abscissa of point 3n). Therefore, the EndOfProfile Flag is
raised. As CAM1 is started in non-periodic mode, the
slave position related to x2 (2n) is identical to the slave
position related to the end of the master range of CAM1,
that is to point 3n.
CAM(EXECUTE:=FALSE); Switch to a new CAM.
CAM(x2, CAM2, PERIODIC:=FALSE); Second evaluation at master position x2. This time the
new cam CAM2 gets evaluated. As CAM2 is started in
relative mode the actual position of the slave (2n) is
added as offset to the CAM2 mapping. So, the start point
of its graph is shifted to point 3n. Its evaluation at
master position x2 results in point 4n situated on the
same line as point 1 and 3n.
3. Wanting to start the CAMs in absolute mode pay attention to an adequate start
position of the slave. If the master range equals the period of the slave there
should be no complications for switching and it does not matter whether the CAM
gets started in periodic mode or not.
In the example described above CAM2 can be started in absolute mode, if both
periods (of master and slave position) equal 360° in accordance to the range of
master values of CAM2.
Otherwise, if the period of the slave is 270° for example (indicated by light blue
lines), the option absolute is not admissible without further arrangements:
In this case the slave is located at 90° at the transition of CAM1 to CAM2. The start
of CAM2 in absolute mode results in a jump to 0° on the grey line. However you can
handle this situation properly by setting the slave offset to the adequate value of
90°.