Siemens SIMATIC FM 353, Manual

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Starting up
7-24
FM 353 Stepper Drive Positioning Module
6ES7 353-1AH01-8BG0
7.3.5 Realigning the reference point coordinates
Axis
To ensure distinct reproducibility of reference recordings, it is necessary for the
synchronizing zero pulse (SYNI) formed by an external zero pulse or by the “cur-
rent-sourcing pattern zero” signal (see Section 9.7.2) to be a distinct distance away
from the reference-point switch (RPS). At low reducing velocities, we recommend
a distance of between 10% and 90% of the distance of one stepper motor revolu-
tion, or the distance of one current-sourcing pattern cycle. For high reducing veloci-
ties, we recommend 30% to 60%. Check this value in the servicing data report
(switch alignment value), and if you find nonconformity to the required value range,
make a corresponding adjustment in the relative position allocation between the
zero pulse encoder or the stepper motor, and the reference-point switch.
Example: Positive search direction
SYNI
Switch readjustment displayed: 40% MD11, 12
(suitable for high reducing speeds)
RPS
Zero pulse
MD11, 12
Set the referencing velocity to the highest value compatible with your require-
ments. It is important for it to be possible to brake to the reducing speed along the
entire length of the reference-point switch (RPS). If this is not the case, an addi-
tional repositioning to the RPS occurs before the search phase begins. Compare
the cycle of the executed traversing movements with Section 9.2.3 and optimize
the referencing speed (MD28).
Then readjust the reference-point coordinates-proper by entering the necessary
reference-point shift in the machine data. After the machine data is activated, the
new reference-point shift takes effect with the next reference point approach.