Siemens SINUMERIK 840D Function Manual page 304

R1: Referencing
10.5 Referencing with incremental measurement systems
Figure 10-6 Synchronization with falling reference cam edge
Case 2: Synchronization with rising reference cam edge
During synchronization with rising reference cam signal edge, the machine axis accelerates to
the parameterized reference point approach velocity against the parameterized reference point
approach direction (traversing direction of the Phase 1):
● MD34020 $MA_REFP_VELO_SEARCH_CAM (reference point approach velocity)
● MD34010 $MA_REFP_CAM_DIR_IS_MINUS (reference point approach in minus direction)
After leaving the reference cam, the machine axis decelerated to standstill:
DB31, ... DBX12.7 == 0
The machine axis then travels back to the reference cam at the parameterized reference point
creep velocity:
MD34040 $MA_REFP_VELO_SEARCH_MARKER (reference point creep velocity)
After reaching the reference cam (DB31, ... DBX12.7 = 1), the machine axis waits for the next
encoder zero mark.
As soon as the encoder zero mark is detected, Phase 2 comes to an end. The machine axis
continues at constant velocity and reference point approach is continued with Phase 3.
Figure 10-7 Synchronization with rising reference cam edge
Electronic reference cam shift
The electronic reference cam shift is used to compensate for expansions of the reference cam
caused by temperature so that synchronization is always to the same encoder zero mark:
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Axes and spindles
Function Manual, 06/2019, A5E47437747B AA