
4.REFERENCE POSITION ESTABLISHMENT B-63323EN-1/03
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4.7 LINEAR SCALE WITH REFERENCE MARKS
General
A scale having reference marks at constantly varying intervals can be
created by combining two virtual scales with different one-rotation
signal intervals. The created scale is referred to as a linear scale with
reference marks. An absolute position on the linear scale with
reference marks can be determined if the reference mark intervals of at
least three adjacent points are detected and if a correlation between the
intervals and the current position is found.
This function measures reference mark intervals by making small
movements on each axis and calculates the absolute position.
Accordingly, a reference position can be established with no axial
movement to the reference position.
Fig. 4.7 (a) Sample Linear Scale with Reference Marks
Basic procedure for establishing a reference position
1. Select jog mode. Set manual reference position return selection
signal IZRN to 1.
2. Perform movement toward the reference position along a desired
axis by setting the corresponding feed axis direction selection
signal (+J1, -J1, +J2, -J2, etc.) to 1.
3. Axial movement is made at the reference position return FL
feedrate (parameter 1425).
4. When a reference mark on the linear scale is detected, the
movement is temporarily stopped and resumed at the reference
position return FL feedrate.
5. Step 4 is repeated until three or four reference marks on the linear
scale are detected. When the absolute position is calculated, the
reference position establishment signal (ZRF1, ZRF2, ZRF3, etc.)
goes to 1.
The timing chart for the basic procedure is shown below:
Reference
mark
Scale 1
Scale 2
42.08.0 8.2 8.4 8.641.8 41.6
50.0
50.0
50.2
50.2
50.2
50.0