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7.3.9
Realigning the Reference Point Coordinates
Axis with Incre-
To ensure distinct reproducibility of reference recordings, it is necessary for
mental Encoder
the synchronizing zero pulse (SYNI) to be a distinct distance away from the
reference point switch (RPS) (see Section9.6.4 for details of generating the
zero reference mark). At low reducing speeds (MD29), we recommend a dis-
tance of 10 % to 90 % and at high reducing speeds, a distance of 30 % to 70
% of the distance of one zero reference mark cycle (e.g. one revolution of the
incremental encoder or the stepper motor). Check this value in the servicing
data report after executing a reference point approach (switch alignment
value) and if you find nonconformity to the required value range, make a
corresponding adjustment in the relative position allocation between the en-
coder and the reference point switch.
Example: Positive search direction
Set the referencing velocity (MD28) to the highest value compatible with
your requirements. It is important to be able to decelerate to the reducing
velocity across the length of the reference-point switch. If this is not the case,
an additional repositioning to the RPS occurs before the search phase of the
synchronizing zero pulse begins. Compare the cycle of the executed travers-
ing movements with Section 9.2.3 and optimize the referencing speed
(MD28).
Then readjust the reference-point coordinates proper by entering the neces-
sary reference-point shift in the machine data. After the machine data is acti-
vated, the new reference-point shift takes effect with the next search for ref-
erence.
Axis with Absolute
In a suitable mode ("jogging", "incremental relative") move to a known point
Encoder (SSI)
on the axis and execute the Set reference point function with the known posi-
tion value. The set position and actual position will immediately be set to this
value, and the allocation of an absolute value to the absolute encoder (SSI)
will be entered in the machine data record (MD17). If you want to archive
this value externally, apart from the module's own data memory, perform a
readout of the machine data DB and save it to a floppy disk or to the hard
disk of your PG.
FM 453 Servo Drive / Step Drive Positioning Module
C79000-G7076-C453-01
RPS
zero pulse
MD12
Switch readjustment displayed: 40 %
(suitable for high reducing speeds)
Starting up the FM 453
SYNI
MD12
7-37
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