Siemens SINAMICS S120 Commissioning Manual page 197

Fine resolution p0419 (XIST_1)
Encoders with their sampling mechanism provide significantly more precise information than
that determined with the pulse counts. They can be evaluated by the drive unit and
transferred as fine resolution to the controller. Change the fine resolution, for example, when
increased precision is required for machining a workpiece.
Fine resolution for incremental encoders
For incremental encoders, the analog signals of the C and D tracks are evaluated. A position
value is determined uniquely via the two analog voltage values in all four quadrants of a
revolution. The analog voltage values allow a high fine resolution, e.g. 11 bits = 2048.
Together with a resolution of 11-bit (= 2048) encoder pulses per revolution this gives a 22-bit
resolution.
Figure 4-65
Fine resolution for TTL/HTL encoders
TTL/HTL pulse encoders operate with digital signals whose fine resolution is less-precise
than that for incremental encoders. The digital signals permit only a fine resolution of 2 bits =
4, because only the signal edges can be counted here.
Figure 4-66
Commissioning with Startdrive
Commissioning Manual, 12/2018, 6SL3097-5AA10-0BP0
Incremental encoders
TTL/HTL encoders
4.8 Basic parameterization of the drive objects
Commissioning
195