Siemens SINAMICS S120 System Manual page 122

Commissioning
4.18 Fine calibration and tuning
Piston calibration with incremental or distance-coded measuring systems
Determining the piston position and calibrating the piston are only possible using
supplementary information from the control system. This is because when switched-off,
encoder signals are lost if the drive has not been configured with an absolute measuring
system. Saving a suitable image of the machine position in the form of a value pair allows
the piston position to be calculated on the drive side from its offset.
For incremental/distance-coded encoders, a reference point approach (homing) is always
required for the associated axis to calculate the piston position after power up. It is not
possible to establish a reference between the machine position and piston position as long
as the axis has not been referenced (validity check).
Determining machine position A
1. Precondition:
The machine/axis is referenced.
2. Retract the piston → piston is at position A
The traversing block to retract the piston comes from the control system.
3. Calibrate
This operation is initiated once using a parameter task as a part of commissioning.
Telegram value G1_MP is transferred as machine position A (MP_A) for the drive.
→ after a validity check, the drive saves the encoder position assigned to piston position
A.
Determining the piston position
1. Drive and control power up
2. After a validity check, the machine position is transferred from the cyclic telegram.
3. The actual piston position is calculated from the actual, absolute encoder position.
4. The piston position is tracked for traversing motion.
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System Manual, 04/2015, 6SL3097-4BA00-0BP1
Hydraulic Drive