Siemens SINUMERIK 840Di Function Manual page 1474

Detailed Description
2.6 Referencing with absolute value encoders
2.6.4 Automatic calibration with probe
Function
In automatic adjustment with a probe, a known position in the machine is approached with
the machine axis from a part program. The position value is stored in the NC as a reference
point value. The position is reached when the probe switches, and the NC then calculates
the reference point offset from the difference between the encoder value and reference point
value.
Note
Part program for automatic adjustment
The part program for automatic adjustment using a probe must be created by the machine
manufacturer/user for the specific requirements of the machine.
Freedom from collision
Because actual-value-related monitoring is not active for the machine axes being referenced,
the machine operator must take special care to ensure that collisions do not occur in the
machine while the machine axes are being moved!
2-34
Note
Activate reference point offset permanently
The entered reference point offset:
MD34090 $MA_REFP_MOVE_DIST_CORR
is activated permanently following a POWER ON - Reset.
If the machine axis is moved after the absolute encoder adjustment without an interim
POWER ON - Reset, the reference point offset entered in the machine data can be
overwritten, for example, as part of an internal overrun offset.
Checking the actual position
Following adjustment of the absolute encoder, we recommend that you verify the actual
position of the machine axis the next time you power up the controller (POWER ON).
Reference Point Approach (R1)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0