Siemens SINUMERIK 840D sl Function Manual page 1564

Detailed description
2.4 Referencing with incremental measurement systems
Figure 2-6
Electronic reference cam offset
Electronic reference cam offset is used for compensating reference cam length increases
caused by temperature:
MD34092 $MA_ REFP_CAM_SHIFT (electronic reference cam offset for incremental
measuring systems with equidistant zero marks)
After a rising or falling reference cam edge is detected the axis is synchronized for the next
encoder zero mark only after the cyclically calculated offset path has been covered.
Because the offset path s
and maximum offset paths s
s
shift_min
s
shift_max
The reference cam offset acts in the direction of zero mark search.
Prerequisite
The reference cam offset is only active for machine axes for which a reference cam has
been parameterized:
MD34000 $MA_REFP_CAM_IS_ACTIVE = 1
18
Synchronization with rising reference cam signal edge
is calculated by the NC in IPO cycles, the following minimum
shift
shift_min
= MD34092 $MA_ REFP_CAM_SHIFT
= MD34092 $MA_ REFP_CAM_SHIFT +
MD34040 $MA_REFP_VELO_SEARCH_MARKER * interpolation cycle
and s will result:
shift_max
Basic logic functions: Reference Point Approach (R1)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0