Siemens SINAMICS S120 Function Manual page 271

Two more encoders can be operated in parallel with the encoders for actual value
preprocessing and position control in order to collect actual values and measured data.
The indexed acquisition of actual values can preprocess a position actual value at each of
the three encoder outputs. The parameter p2502[0...3] is used to select the encoder
evaluation for position control.
The parameters of the indexed actual value acquisition are indexed four times. The indexes
1..3 are assigned to the encoder evaluations 1..3. The index 0 is assigned to position control.
The parameter r2521[0...3] can be used to retrieve the current actual values of all connected
encoders. For example, the position actual value for position control in r2521[0] is identical
with the value r2521[1] if the position control uses encoder evaluation 1. The signal source
for a position offset can be set in parameter p2516[0...3].
The absolute encoder adjustment is initiated via p2507[0...3].2, and its successful completion
is reported via p2507[0...3].3. The signal source "Reference point coordinate for the position
controller" p2598[0] is interconnected with p2599 during basic positioning. The other signal
sources are not interconnected in the standard configuration.
The measuring probe evaluation can be enabled for the encoder evaluation x, which is not
assigned to position control, via p2509[x]. The signal sources are assigned via p2510[0...3],
the edge evaluation is set via p2511[0...3]. The measured value is then available in r2523[x]
if the status wird for encoder x (Geber 0: r2526.0..9, encoder1: 2627.0..2, encoder2:
r2628.0..2, encoder3: r2529.0..2) has the "Valid measurement" bit set.
The current values of the position actual values of the different encoders can be read out via
parameter r2521[0...3]. These position actual values can be corrected with a signed value
from p2513[0...3] after a 0/1 signal from the signal source in p2512[0...3].
In addition, the velocity actual value (r2522[0...3]) and the position offset for absolute
encoders p2525[0...3] can be processed for each encoder by the higher-level controller.
Drive functions
Function Manual, (FH1), 10/2008, 6SL3097-2AB00-0BP5
Function modules
7.8 Closed-loop position control
271