IDEC MICROSmart FC6A Series Ladder Programming Manual page 293

Example: Overlapping Coordinates
In this example, the XYFS instruction sets up three coordinate points, which define two different linear relationships between X
and Y. The three points are: (X0, Y0) = (0, 100), (X1, Y1) = (100, 0), and (X2, Y2) = (300, 100). The two line segments define
overlapping coordinates for X. That is, for each value of Y within the designated range, there would be two X values assigned.
XYFS(I)
M8120
CVXTY(I)
I0
CVYTX(I)
I1
D90 (75)
D95 (40)
The first line segment defines the following relationship for X to Y conversion:
Y = – X + 100
The second line segment defines another relationship for X to Y conversion:
1
Y = – X – 50
2
For X to Y conversion, each value of X has only one corresponding value for Y. If the current value of counter C10 is 250, the value assigned to D90
is 75.
For Y to X conversion, the XYFS instruction assigns two possible values of X for each value of Y. The relationship defined by the first two points has
priority in these cases. The line between points (X0, Y0) and (X1, Y1), that is, the line between (0, 100) and (100, 0), has priority in defining the
relationship for Y to X conversion (X = –Y + 100).
Therefore, if the value in data register D95 is 40, the value assigned to D30 is 60, not 180.
Exactly the same two line segments might also be defined by the XYFS instruction, except that the point (300, 100) could be assigned first, as (X0,
Y0), and the point (100, 0) could be defined next, as (X1, Y1). In this case, this linear relationship would have priority.
In this case, if the value in data register D95 is 40, the value assigned to D30 is 180, not 60.
S1 X0 Y0
0 0 100
S1 S2 D1
0 C10 D90
S1 S2 S1
0 D95 D30
(X0, Y0)
Y
(0, 100)
100
(X1, Y1)
(100, 0)
0
D30 100
(60)
FC6A S MICROS
ERIES MART
16: C
X1 Y1 X2
100 0 300
C10
(250)
L P M
ADDER ROGRAMMING
C
OORDINATE ONVERSION
M8120 is the initialize pulse special internal
Y2
relay.
100
At startup, XYFS specifies three points.
CVXTY converts the current value in C10 and
stores the result in D90.
CVYTX converts the value in D95 and stores
the result in D30.
END
(X2, Y2)
(300, 100)
300 X
FC9Y-B1726
ANUAL
I
NSTRUCTIONS
16-5