Selector Gearboxes; Taking Into Account Selector Gearboxes - Siemens SINUMERIK 840D sl Function Manual

Basics regarding the safety functions integrated in the system/drive
6.4 Actual value conditioning
Interlocking the user agreement
Before a user agreement can be issued, the interlock must be cancelled:
● Key-operated switch
in setting 3 → the user agreement can be issued
After the user agreement has been issued, the interlocking must be again set (e.g. key switch
position 3 must be left and the key withdrawn).
6.4.5

Selector gearboxes

6.4.5.1

Taking into account selector gearboxes

The possible gearbox ratios must be known in order that the NC and drive can evaluate the
position actual values referred to the load.
For this purposes, various gearbox ratios can be selected on an axis-for-axis basis in the
machine data and selected using the "Safety-related inputs/outputs" (SGEs/SGAs).
The following points must be carefully observed for drives with selector gearboxes (these are
generally used with spindles).
● If the drive is operated with an (indirect) encoder (motor measuring system), i.e. the safety-
related actual value for the NCK and drive are derived from the same measuring system,
then the gearbox ratios (gearbox stage selection for Safety Integrated) must also be
selected for both monitoring channels. The state of the SGE signals ratio selection (bits
0..2) is not subject to a crosswise data comparison; however, the safety-related actual
values from the NCK and drive are compared to evaluate if there is any deviation (< 36942
$MA_SAFE_POS_TOL or parameter p9542 SI Motion, actual value comparison tolerance
(crosswise) (Control Unit)).
● If the drive is operated with an (indirect) motor encoder and a (direct) spindle encoder, the
safety-related actual values are derived from the direct encoder and those of the drive from
the indirect encoder. For the direct encoder, the gearbox changeover is not relevant and
the gearbox stage changeover only has to be configured/engineered for the drive.
● Using the two machine data fields
MD36921[0..7] $MA_SAFE_ENC_GEAR_DENOM[n] denominator, gearbox encoder/load
and
MD36922[0..7] $MA_SAFE_ENC_GEAR_NUMERA[n] numerator gearbox ratio encoder/
load
or
p9521[0..7] SI Motion gearbox encoder/load denominator (Control Unit) and
p9522[0..7] SI Motion gearbox encoder/load numerator (Control Unit)
8 different gearbox stage pairs for NCK/drive can be defined. For this definition, there is
no special function for an index value - e.g. interdependency on the operating mode of the
spindle. These 8 pairs must be parameterized and selected depending on the encoder
configuration.
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Function Manual, 12/2017, 6FC5397-4BP40-6BA1
Safety Integrated