Siemens SINAMICS G120 - Normalizing the Encoder Signal; Define the Resolution

6.2 Normalizing the encoder signal
6.2.1 De󹪝ne the resolution
Distance unit (LU): the resolution of the position actual value in the converter
The converter calculates the position actual value of the axis using the neutral position unit LU
(Length Unit). The distance unit LU is independent of whether the converter controls e.g. the
position of an elevating platform or the angle of rotary table.
Firstly, for your application de󹪝ne the required resolution. In other words: Which distance or
angle corresponds to the length unit (LU)?
The following rules apply when selecting the distance unit LU:
1. The higher the resolution of the distance unit LU, the higher the accuracy of the position
control.
2. If you select a resolution that is too high, then the converter cannot represent the position
actual value over the complete axis traversing range. The converter responds with a fault in
the case of an over󹪞ow when representing the number.
3. The resolution of the distance unit LU should be less than the maximum resolution that is
obtained from the resolution of the distance-encoder.
Normalize the encoder signal
Requirements
• You are online with Startdrive.
• You have selected the "Mechanical system" screen.
• You have de󹪝ned the required resolution for your particular application, e.g. 1 LU ≙ 1 µm or
1 LU ≙ 1/1000° (1 millidegree).
Procedure
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1. Enable the settings so they can be edited.
2. Enter the gear ratio of the axis: Load revolutions.
Commissioning
6.2 Normalizing the encoder signal
Basic positioner
Function Manual, 09/2020, FW V4.7 SP13, A5E34257659B AG 37