Referencing In Follow­up Mode - Siemens SINUMERIK 828D Function Manual

R1: Reference point approach
15.8 Referencing in follow­up mode
15.8 Referencing in follow­up mode
Function
Incremental measuring systems and measuring systems with distance-coded reference marks can be referenced
even when the machine axis is in follow-up mode. This requires that reference point approach be properly
parameterized according to the measuring system in use (see "Referencing with incremental measuring
systems" and "Referencing with distance-coded reference marks").
When referencing in follow-up mode the machine axis is moved not by the NC but by means of an external travel
movement over the encoder zero mark and the parameterized number of distance-coded reference marks. The
measuring system is referenced when the encoder zero mark or parameterized number of distance-coded
reference marks are detected.
Note
Reproducibility of the referencing result
In NC-guided reference point approach, reproducibility of the referencing result is ensured
through adherence to the assigned traverse velocities during the referencing operation.
During referencing in follow-up mode, responsibility for achieving reproducibility of the
referencing results lies with the machine manufacturer / user.
Unique zero mark
Referencing of an incremental measuring system is based on the explicit position of the encoder zero mark
relative to the overall traversing range of the machine axis.
Because the reference cam signal is not evaluated by the NC during referencing in follow-up mode, unique
identification of the reference point when referencing in follow-up mode will only result with:
• Only one encoder zero mark in the traversing range of the machine axis
• Linear measuring systems with distance­coded reference marks
• Modulo rotary axes (absolute position within one revolution)
Zero mark selection when several zero marker signals occur
If several encoder zero marks are detected in the traversing range of the machine axis due to machine-specific
factors, e.g., reduction gear between encoder and load, a BERO must be mounted on the machine and
connected to the relevant drive module (SIMODRIVE 611D) via a BERO input in order to uniquely specify the
reference point. The position of the reference point is then derived from the combination of BERO signal and
encoder zero mark.
Zero mark evaluation with BERO must be parameterized as the referencing mode:
MD34200 $MA_ENC_REFP_MODE = 5
Negative edge evaluation
In the case of a referencing operation with a negative edge evaluation of the BERO signal:
MD34120 $MA_REFP_BERO_LOW_ACTIVE = FALSE
synchronization is with the next encoder zero mark encountered after the BERO is exited.
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Function Manual, 09/2011, 6FC5397-0BP40-2BA0
Basic Functions