MPH-02, MPB-02, MPD-02
Requirements for Selecting a
Reference Mark
Distance Monitoring
Home Switch Edge/
Reference Mark
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!
reference marks
detection
home switch signal
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
critical distance
< 0.25 * reference mark distance
optimum distance
0.5 * reference mark distance
allowed distance
(0.25 ... 0.75) * reference mark
range
distance
Fig. 8-13:
Data for distance between home switch signal and reference mark
Drive Functions
reference marks selected by
home switch signal
1 motor
revolution
range of inaccuracy
reference travel direction
8-15
DF0076v1.fh7
Drive reaction
shutdown with
C0602
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