8
8-8
FM 351 Positioning Function Module
EWA 4NEB 720 6001-02
Table 8-3 Machine Data for the Axis, continued
Machine Data and
Assignment
Description
Reference point
coordinate
– 1,000,000.000 mm
to
+ 1,000,000.000 mm
Incremental encoder:
You determine the reference point by synchronization, that is, via the setting Set ref-
erence point or the Seek-reference-point mode. If the synchronization event is de-
tected (for example, zero mark of the encoder during a seek-reference-point travel),
the reference coordinate is allocated to this event.
During the selection of the value for the reference-point coordinate you must take
into account that the value must be located within the working range, that is between
the Software Limit Switch Start (SLS) and the Software Limit Switch End (SLE)
(including the values of the limit switches).
–1000,000 1000,0000
SLESLS
Axis
Reference-point coordinate 500.000 mm; the value lies within the accepted soft-
ware limit switches.
Reference-point coordinate 1500.000 mm; the value lies outside the software limit
switches and is not allowed.
1
2
1
2
Absolute encoder (SSI)
A parameterized axis with an absolute encoder is always synchronized provided no error
is detected.
In this respect, also read the description of the absolute encoder adjustment and Chap-
ter 8.4 which describes the relationship of the absolute encoder adjustment and the
other data.
Absolute encoder adjust-
ment
0 to (2
25
–1)
This entry is only significant for absolute encoders. It must be smaller or equal to the
total number of steps on the absolute encoder.
Together with the value Reference-point coordinate, the value of the absolute encoder ad-
justment forms a pair of values. This pair of values determines the relationship between
the encoder and the axis coordinate system. An unambiguous value of the coordinate sys-
tem is allocated to each absolute encoder value.
Also read the Chapter Absolute Encoder Adjustment.
Type of seek–reference-
point mode
positive reference-point
switch left
negative reference-
point switch left
positive reference-point
switch right
negative reference-
point switch right
With the type of seek-reference-point mode you determine the conditions for the axis
synchronization for operation with an incremental encoder.
The first statement defines the start direction in which the seek-reference-point
travel starts.
The second part defines the position of the zero mark leading to synchronization.
The reference point is located at the first zero mark after leaving the reference-
point switch in the specified direction.
The application of this data is described in Chapter 9.4.
Machine Data and Increments
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