Festo SEC-AC-305-CO, Manual

Page: 192 / 272

7. Operating modes/Adjustment of the Operating Mode
7−14
Festo P.BE−SEC−AC−CO−E N en 0802a
Description of Features
Usually it is necessary to know the absolute position for posi
tioning motions. For various reasons servo controller mostly
have no absolute angle encoder so that a search for reference
is necessary in almost all cases after resetting the device. A
number of different methods is kept ready for that. The
method that is necessary for the application can be selected
via the object
homing_method
.
There are four possible signals for the homing operation: the
negative and positive limit switch, the reference switch and
the (periodic) zero impulse of the angle encoder. Besides this
the controller can refer to the negative or positive endstop
without additional signal.
If a method of reference has been determined via the object
homing_method the following adjustments are fixed by that:
The signal for the reference (negative or positive limit
switch, the reference switch, negative or positive end
stop)
The direction and process of the homing operation
The kind of evaluation of the zero impulse of the used
angle encoder
The different methods for the homing operation are shown in
the following diagrams. The encircled numbers correspond to
the code that has to be entered in the object
homing_method .