Siemens SINUMERIK 840D sl Function Manual page 1177

Zero mark selection when several zero mark 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 via a digital input of the NCU interface in order to
clearly determine the reference point.
Note
BERO signal: Zero mark selection
The processing of the BERO signal is performed exclusively in the drive. Connection and
parameterization, see Section "Hardware signals (Page 1154)".
Enable
The "Referencing in follow-up mode" function is enabled with:
MD34104 $MA_REFP_PERMITTED_IN_FOLLOWUP = TRUE
Starting the referencing operation
If the machine axis is in follow-up mode (DB31, ... DBX61.3 == TRUE) at the start of reference
point approach, the measuring system is referenced in follow-up mode.
If the machine axis is not operating in the follow-up mode at the start of reference point
traversing, the "normal" from the NC-controlled reference point travels is carried out.
Referencing in follow-up mode can be started in the following modes:
● JOG-REF: Traversing keys
● AUTOMATIC: Part program command G74
Sequence of the referencing operation (JOG-REF mode)
1. Activate follow-up mode of machine axis:
DB31, ... DBX1.4 (follow-up mode) = 0
DB31, ... DBX2.1 (controller enable) = 0
2. Take into account activation of follow-up mode:
DB31, ... DBX61.3 (follow-up active) = 1
3. Switch to JOG-REF mode.
4. External motion of machine axis across encoder zero mark or parameterized number of
distance-coded reference marks. The referencing operation is started internally in the NC
as soon as the machine axis is moved:
DB31, ... DBX61.4 (axis/spindle stationary) = 0
5. The measuring system is referenced after the encoder zero mark or the assigned number
of distance-coded reference marks have been successfully detected:
DB31, ... DBX60.4/60.5 (referenced/synchronized 1/2) = 1
Aborting the reference operation
Basic Functions
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
R1: Referencing
15.8 Referencing in follow-up mode
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