Referencing Variants Not Supported; Automatic Restoration Of The Machine Reference; Overview - Siemens SINUMERIK 840D Function Manual

R1: Referencing

10.10 Automatic restoration of the machine reference

10.9.9

Referencing variants not supported

The following referencing variants are not supported when used with absolute encoders:
● Referencing/calibrating with encoder zero mark
● Distance-coded reference marks
● Proximity switch with two-edge evaluation
10.10 Automatic restoration of the machine reference
10.10.1

Overview

Without a defined machine reference when traversing machine axes, no position-dependent
functions such as transformations or tool frames can be executed. In different machine
situations, these functions must immediately be available for traversing axes when the encoder
is activated, e.g. after the controller is switched on or after the parking of a machine axis has
ended (see Function Manual "Monitoring and Compensating"). However, the machine axes
should not or cannot be traversed again for referencing.
Absolute encoders
For measuring systems with adjusted absolute encoders, the machine reference is restored
immediately without any additional measures when the encoder value is read.
Incremental encoders
With incremental measuring systems, the machine reference can be restored without
traversing the axes through "Automatic referencing" or "Restoration of the actual position".
Boundary conditions
Incorrect synchronization of the position measuring system caused by offset of the actual
machine axis position
During the time in which the measuring system of the machine axis is switched off, it is not
permissible that the axis is mechanically moved. Otherwise this results in an offset between
the last buffered actual position and the real actual position of the machine axis. This would
lead to an incorrect synchronization of the measuring system resulting in danger to personnel
and machine.
The machine manufacturer must provide such measures as holding brakes, etc. on the
machine so that the actual position is not changed, and this must be ensured by the user. The
responsibility for this rests exclusively with the machine manufacturer / user.
If axis motion cannot be prevented mechanically in the shutdown state, either an absolute
encoder must be used or the axis must be referenced again with reference point approach
after switching on.
332
WARNING
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA