Siemens SINUMERIK 840D sl Commissioning Manual page 315

Constraints
The operating range is currently limited to the following:
● Only one gear stage can be optimized.
● The spindle cannot be optimized in axis mode.
● Only one spindle can be selected for the path calibration when tapping.
CNC Commissioning: NC, PLC, Drive
Commissioning Manual, 12/2019, A5E48312804B AA
10.4 Spindle optimization (automatic)
Drive tuning
315