User guide

3. Drive functions
3−36
Festo P.BE−CPX−CMA X−CONTROL−EN en 0908NH
3.2.2 Homing
For drives with incremental measuring systems, homing must
have been carried out before a positioning task can be done.
Homing can be carried out in each supported operating mode
except for parametrising mode.
The drive references with respect to a stop or, as a special
case, the current position. Reaching the stop is
detected
when the piston comes to a standstill. Here, the possibility
that this standstill was caused by a lack of air pressure must
be ruled out.
Since the axis zero point for pneumatic axes must fundamen
tally be placed at the cylinder zero point, the drive (as op
posed to electric drives, for example)
does not automatically
move to this zero point.
For a description of the homing methods, see section 3.2.4.
General homing information
 The axes lose their reference:
 when switched off, reset, etc.
 possibly when there are errors in the sensor interface
or axis string
 when homing is started again.
If the drive has a position measuring
system with an abso
lute encoder, homing is not possible. An edge at the
CPOS.HOME input leads to a fault. No movement is in
itiated.