Siemens SINUMERIK 840D Function Manual page 320

R1: Referencing
10.8 Referencing in follow-up mode
Aborting the reference operation
An active referencing operation can be aborted by:
● Deselecting follow-up mode
● NC reset
Response when measuring systems are already referenced
A measuring system that has already been referenced can only be re-referenced in
AUTOMATIC mode using part program command G74.
Sequence of referencing operation (AUTOMATIC mode)
1. Switch to AUTOMATIC mode.
2. Start the part program.
3. Activate follow-up mode of machine axis:
DB31, ... DBX1.4 (follow-up mode) = 1
DB31, ... DBX2.1 (controller enable) = 0
4. Wait for activation of follow-up mode:
DB31, ... DBX61.3 (follow-up active) == 1
5. The referencing operation is started internally in the NC as soon as G74 command has been
processed.
6. External motion of machine axis across encoder zero mark or parameterized number of
distance-coded reference marks.
7. The measuring system is referenced after the encoder zero mark or the assigned number
of distance-coded reference marks have been successfully detected: The following NC/
PLC interface signal is set as feedback:
DB31, ... DBX60.4 / 60.5 (referenced/synchronized 1/2) == 1
8. The block change occurs after the referencing operation has been successfully completed.
Aborting the reference operation
An active referencing operation can be aborted by:
● Deselecting follow-up mode
● NC reset
Response when measuring systems are already referenced
A measuring system that you have already referenced can be re-referenced.
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Axes and spindles
Function Manual, 06/2019, A5E47437747B AA