Siemens SINAMICS S120 Commissioning Manual page 417

HTL encoder operation
Figure A-4
After evaluation of the zero crossings and digitization of the two signals, pulse sequences
are available that permit direction-independent path evaluation.
Absolute position
After switching on the machine, the absolute dimensional reference for the machine zero
must be established with pulse encoders for positioning. Therefore, perform a homing
procedure. After homing, the absolute position is determined by adding up the individual
incremental signals.
Commissioning with Startdrive
Commissioning Manual, 11/2017, 6SL3097-4AA10-0BP1
TTL incremental encoder
A.6 Overview of measuring systems / encoders
Appendix
417