6Functions
30 Festo – GDCP-CMMP-M0-FW-E N – 1304NH
6.2 Homing
For absolute positioning, homing must be executed and the dimensional reference
system defined at initial commissioning. If the drive does not use a multi-turn absolute
encoder, homing must be repeated at eac h switch-on or reset.
To be able to travel to an absolute, unique position in the positioning range, the drive must be refer-
enced to a measuring reference system.
Homing of the drive comprises:
–Homing
– Establishment of the axis zero point
– Definition of the dimensional referenc e system.
With h oming, the c orrec t zero position is determined by means of a reference signal. The reference
signal trigger defines the reference point of the dimensional reference system. The reference point is
the absolute point of reference for the axis zero point. In the factory setting, the axis zero
point = project zero point.
The reference signal supplies, for example, a switch th at is triggered at a known, unique position on the
travel path. Also, dependent on the motor encoder, additional signals (e.g. encoder zero track) can be
evaluated to increase accuracy. You establish the used signals via the homing method.
6.2.1 Homing methods
The homing methods are oriented on CiA 402.
With some motors (those with absolute encoders, single- or multi-turn), the drive may be
permanently referenced. In such cases, methods involving homing to an index pulse
(= zero pulse) might not cause homing to be carried out; rather the drive will move
directly to the axis zero point (if it has been entered in the parameters).
The drive homes against a stop, a limit switch or a referenc e switch. The motor current increases when
the drive reache s a stop. Since the drive must not continuously home against the sto p, it must move at
least one millimetre back into the stroke range.
Procedu re:
1. Search for the homing point corresponding to the configured method.
2. Run relative to the reference point around the “Offset axis zero point”.
3. Set at the axis zero point: Current position = 0 – offset project zero point.
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