Instruction manual

Integer Compares
68
890USE18300 September 2003
Delta (∆) You can also add a ∆ value to an outside-the-window compare, which acts as an
hysteresis around the two thresholds.
Suppose you have a window defined by TH 1 = -10 000 and TH 2 = +4000. To that
window, you specify a ∆ of 2000. If your operational input value is less than or equal
to TH 1 - ∆ (less than or equal to -12000)and is increasing in value, the reflex output
is 1. The output remains 1 until the input value reaches -8000, at which point the
output drops to 0. If the input value continues to increase, the output remains at 0
until the input value exceeds TH 2 + ∆ (+6000). When the input value exceeds
+6000, the output rises back to 1.
If, on the other hand, the input value is decreasing from a value greater than
TH 2 + ∆ (greater than +6000), the reflex output is 1 until the point where the input
value reaches +2000. At this point, the output drops to 0 and remains at 0 as the
input value decreases beyond TH 1 - ∆ (less than -12 000). At this point, the output
rises back to 1:
While the input value is inside the area defined by the threshold and the ∆, it holds
its last value.
For example, if the input value is inside the window and increasing, the output will
be 0. When it exceeds +6000, the output rises to 1. If the input value then begins to
decrease after the output has dropped, the output will remain there until the input
value decreases to +2000, at which point it will drop to 0 and will remain there until
the input value decreases beyond -12 000.
Note: To be valid, TH 2 - TH 1 must be greater than 2∆. For example, say that
TH 1 = -10 000 and TH 2 = +4000. The ∆ value you assign to the reflex action must
therefore be less than 7000.
1
-32 768
-8000
0
input value
+6000
-10 000 (TH 1)
1
+4000 (TH 2)
-32 768
+32 767
0
input value
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+32 767