Siemens SINUMERIK 840D Function Manual page 305

MD34092 $MA_ REFP_CAM_SHIFT (electronic reference cam shift for incremental measuring
systems with equidistant zero marks)
With the electronic reference cam shift, synchronization is not performed immediately to the
next encoder zero mark after detection of the reference cam edge, but only after the
parameterized offset distance has been traversed.
Due to the determination of the distance traversed in the interpolator clock cycle since the
detection of the reference cam edge, the effective shift distance is s
s
shift_min
s
shift_max
The electronic reference cam shift acts in the direction of zero mark search.
①
Figure 10-8
Requirement
The electronic reference cam shift is only active for machine axes with reference cam:
MD34000 $MA_REFP_CAM_IS_ACTIVE == 1
Reference cam adjustment
Encoder with equidistant zero marks
Always ensure that the reference cam of encoders that supply zero marks at equidistances is
accurately adjusted so that the correct zero mark is always detected during reference point
approach.
Dynamic response
The following factors influence the dynamic response from the arrival of the reference cam to
the machine up to the detection of reference cam signals transferred from the PLC user
program to the NC:
● Switching accuracy of the reference cam switch
● Delay of the reference cam switch (NC contact)
● Delay at the PLC input
● PLC cycle time
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA
= MD34092 $MA_ REFP_CAM_SHIFT
= MD34092 $MA_ REFP_CAM_SHIFT +
MD34040 $MA_REFP_VELO_SEARCH_MARKER * interpolator clock cycle
Reference cam shift
Electronic reference cam shift
10.5 Referencing with incremental measurement systems
R1: Referencing
:
shift
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