19: COORDINATE CONVERSION INSTRUCTIONS
19-6 « FC4A MICROSMART USER’S MANUAL »
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.
The first line segment defines the following relationship for X to Y conversion:
The second line segment defines another relationship for X to Y conversion:
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.
M8120 is the initialize pulse special
internal relay.
At startup, XYFS specifies three points.
CVXTY converts the value in C10 and
stores the result in D90.
CVYTX converts the value in D95 and
stores the result in D30.
M8120
XYFS(I)
Y2
100
END
I0
CVXTY(I) D1
D90
I1
CVYTX(I) S1
D30
S1
0
X0
0
Y0
100
X1
100
S1
0
S2
C10
S1
0
S2
D95
X
Y
0
D30 C10
D95 (40)
D90 (75)
300
Y1
0
X2
300
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