Siemens SINAMICS S120 Function Manual page 530

Function modules
8.8 Basic positioner
Evaluating the BERO signal
You have the option of either evaluating the positive or negative signal edge of the BERO
signal:
● Positive edge (factory setting)
For referencing with a positive edge evaluation of the BERO signal, the encoder interface
supplies the position of that reference mark, which is directly detected after the positive
edge of the BERO signal. If, mechanically, the BERO is sized in such a way that the
BERO signal covers the entire width of the encoder zero mark, the required encoder zero
mark will be reliably detected in both traversing directions.
● Negative edge
For referencing with a negative edge evaluation of the BERO signal, synchronization is
realized to the next reference mark after leaving the BERO signal.
Setting referencing
Proceed as follows to parameterize referencing with several zero marks:
1. Using parameter p0493, define the fast digital input to which the BERO is connected.
2. Set the corresponding bit of parameter p0490 to 1.
The signal inversion means that the evaluation uses the negative edge of the BERO
signal.
Referencing procedure
Referencing then proceeds as follows:
1. Via the PROFIdrive encoder interface, the Control Unit receives the request for a
reference mark search.
2. Using the parameterization, the Control Unit determines the zero mark depending on the
BERO signal.
3. The Control Unit provides the (possibly corrected) zero mark position as reference mark
via the PROFIdrive encoder interface.
Note
At high speeds or if the distance between the BERO signal and the following zero mark is
too low, then it is possible that the required, next zero mark is not detected, but instead, a
subsequent one due to the computation time. Due to the known zero mark distance, in this
particular case, the determined position is correspondingly corrected.
When using a measuring gear, the zero mark position depends on the motor revolution. In
this case, a correction is also performed and for each motor revolution a reverse calculation
is made back to the position of the zero mark with the shortest distance BERO signal ↔ zero
mark.
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Function Manual, 11/2017, 6SL3097-4AB00-0BP5
Drive functions