MPH-02, MPB-02, MPD-02
Drive Functions
8-15
DOK-INDRV*-MP*-02VRS**-FK01-EN-P
Note:
Generally, several reference marks can occur in the
"activated" range of the home switch signal!
But in the case of encoders with distance-coded reference
marks, at least two marks have to occur in the "activated"
range of the home switch!
If the home switch is to be used for selecting a reference mark signal (in
the case of several signals occurring over the travel range), you have to
make sure that it is always the same reference mark signal that is
evaluated by the controller for detecting the position of the dedicated
point!
The controller recognizes the home switch activation with a position
inaccuracy inherent in the system. It depends on:
•
the input clock of the digital input via which the home switch is
evaluated (corresponding to the position controller clock when
command C0600 is executed)
- and -
•
the velocity at which the axis moves at the time the home switch is
activated.
Within this range of inaccuracy of the position detection there mustn’t
occur any encoder reference mark, because reliably reproducible
detection of the dedicated point is impossible within this range!
DF0076v1.fh7
reference travel direction
range of inaccuracy
detection
home switch signal
reference marks
reference marks selected by
home switch signal
1 motor
revolution
Fig. 8-12:
Ambiguous detection of reference marks in range of inaccuracy of
home switch detection
Due to the range of inaccuracy of home switch evaluation, the distance
between the home switch edge and the position of the next reference
mark is monitored. If the distance between the home switch edge and the
reference mark falls below a certain value, the
C0602 Distance home
switch - reference mark erroneous
error message is generated.
Classification of
distance
Distance
Drive reaction
critical distance
< 0.25 * reference mark distance
shutdown with
C0602
optimum distance
0.5 * reference mark distance
---
allowed distance
range
(0.25 ... 0.75) * reference mark
distance
---
Fig. 8-13:
Data for distance between home switch signal and reference mark
Requirements for Selecting a
Reference Mark
Distance Monitoring
Home Switch Edge/
Reference Mark
Courtesy
of
CMA/Flodyne/Hydradyne
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Motion
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426-5480
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