Siemens SINAMICS S120 Function Manual page 518

Function modules
8.8 Basic positioner
Note
Referencing of distance-coded zero marks is not supported.
Set reference point
The reference point can be set using a 0/1 edge at binector input p2596 (set reference point)
if no traversing commands are active and the actual position value is valid (p2658 = 1
signal). A reference point can also be set for an intermediate stop.
The current actual position of the drive is set here as the reference point using the
coordinates specified by connector input p2598 (reference point coordinates). The setpoint
(r2665) is adjusted accordingly.
This function also uses actual position value correction for the position controller (p2512 and
p2513). Connector input p2598 is connected to adjustable parameter p2599 as standard.
The binector input is not effective for the traversing task being presently executed.
Absolute encoder adjustment
Absolute encoders have to be adjusted during commissioning. After the machine has been
switched off, the position information of the encoder is retained.
When p2507 = 2 is entered, using the reference point coordinate in p2599, an offset value
(p2525) is determined. This is used to calculate the actual position value (r2521). Parameter
p2507 signals the adjustment with a "3" - in addition bit r2684.11 (reference point set) is set
to "1".
The offset of the encoder adjustment (p2525) should be saved in a non-volatile fashion
(RAM to ROM) to permanently save it.
Note
If an adjustment is lost for an already adjusted axis, the axis will remain unadjusted even
after a POWER ON of the drive unit. The axis needs to be adjusted again in such cases.
Rotary absolute encoder
During adjustment with the rotary absolute encoder, a range is aligned symmetrically around
the zero point with half the encoder range within which the position is restored after switch
off/on.
If position tracking is deactivated (p2720.0 = 0), only one encoder overflow is permitted to
occur in this range (for further information, see Section Actual position value processing
(Page 488)).
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Function Manual, 11/2017, 6SL3097-4AB00-0BP5
Drive functions