Technical data

Basic functions
4.1 Encoder settings
Connection of the SINAMICS S120 to the Technology CPU
Product Information, 09/2011, A5E00480378-04
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4.1.4 Encoder types
Encoder type - incremental encoder
Incremental encoders output the value zero after the supply voltage has been interrupted.
Axes with incremental encoders must be rereferenced after each voltage interruption.
Encoder type - absolute encoder
Absolute encoders can also provide the absolute position value after the supply voltage of
the drive control unit has been interrupted. This must be requested for each encoder function
from the PLC to the drive unit.
Special features of absolute encoders
The following selection possibilities are available in the
"Axis configuration - Encoder assignment" dialog for the selection of an absolute encoder:
● Absolute value encoder:
In this case, the total number of overflows of the absolute actual value will not be saved
when the technology CPU is switched off.
At the next switch on, the actual position value will be formed only from the absolute
actual value that the converter passed to the technology CPU in Gn_XIST_2.
For a multiturn resolution of 4096 and a leadscrew pitch of 10 mm/revolution,
this always produces a value that lies between 0 m and approx. 40 m.
This setting of the absolute value encoder is normally used for encoders for rotary axes
(modulo axes). For this setting, the complete traversal area must be covered by the
absolute value encoder.
● Absolutely cyclic absolute encoder
In this case, overflows of the multiturn information will be saved in the remanent memory
area of the technology CPU on shutdown and will be used to calculate the actual position
value at the next start up.
This setting must be made if the absolute encoder with its multiturn resolution does not
cover the total traversing range of the axis, and it is possible for the multiturn information
to overflow within the traversing range. Cyclical absolute should be selected especially for
the resolver encoder structure.