Siemens SINUMERIK 840D sl Function Manual page 1588

Detailed description
2.6 Referencing with absolute value encoders
Signal propagation delay compensation
The signal propagation time can cause corruption of the absolute position detected by the
NC. The signal propagation time can be compensated for in any direction:
MD31122 $MA_BERO_DELAY_TIME_PLUS (BERO delay time plus)
MD31123 $MA_BERO_DELAY_TIME_MINUS (BERO delay time minus)
Note
Prerequisite for a correct compensation of signal propagation time is drives of type
SIMODRIVE 611 digital. The compensation times are pre-set in delivery condition in such a
way that changes are usually not required.
Creep velocity
If with the approach of BERO, it is to be proceeded with the parameterized reference point
creep velocity (MD34040 $MA_REFP_VELO_SEARCH_MARKER) then "BERO with
projected start velocity with spindles" must be parameterized as reference mode:
MD34200 $MA_ENC_REFP_MODE = 7
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Basic logic functions: Reference Point Approach (R1)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0