
B--63003EN--1/02
4. REFERENCE POSITION ESTABLISHMENT
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The linear scale with absolute addressing reference marks has reference
marks (one--rotation signals) at intervals that change at a constant rate.
By determining the reference mark interval, the corresponding absolute
position can be deduced. The CNC makes a small movement along an
axis to measure the one--rotation signal interval, then calculates the
absolute position. The reference position can be established without
performing positioning to the reference position.
50.0
50.2
8.0
42.0 8.2 41.8 8.4 41.6 8.6 41.4
Reference marks
Reference mark 1
Reference mark 2
Fig. 4.8 (a) Sample linear scale with absolute addressing reference marks
(1)Select JOG mode, then set manual reference position return selection
signal ZRN to 1.
(2) Set the feed axis direction selection signal (+J1, --J1, +J2, --J2, etc.),
corresponding to the axis for which the reference position is to be
established, to 1, then feed the tool along that axis.
(3)The tool is fed along the selected axis at the reference position return
FL feedrate (parameter No. 1425).
(4) Upon the detection of a reference mark sent from the linear scale, the
tool is stopped briefly, then fed again at the reference position return
FL feedrate.
(5) Step (4) is repeated until three or four reference marks are detected.
Then, the absolute position is calculated and the reference position
established signal (ZRF1, ZRF2, ZRF3, etc.) is set to 1.
If the feed axis direction selection signal (+J1, --J1, +J2, --J2, etc.) is set
to 0 at any point in steps 2 to 5, feed does not stop and establishment of
the reference position is continued.
A time chart for the above basic procedure is shown below.
4.8
LINEAR SCALE WITH
ABSOLUTE
ADDRESSING
REFERENCE MARKS
General
Basic procedure f o r
establishing the
reference position