Instruction manual

Integer Compares
60
890USE18300 September 2003
Operational
Input
A greater-than-threshold integer compare block uses one operational input. This
input needs to be a word with a signed integer value in the range -32,768 to +32,767.
The input can come from:
an analog input from a module on the island
an analog output from the virtual module
if the compare is the second block in a nested reflex action (See Nesting Two
Reflex Blocks, p. 36), the operational input may be configured as the output of the
first reflex block
Threshold and ∆ You need to enter two values—threshold and the ∆. The threshold is the value
against which the operational input is compared. You can also add a ∆ value to the
threshold, which acts as an hysteresis.
For example, say you assign a threshold value of 1600 to the block. You then assign
a ∆ value of 32 to that threshold. If your operational input value is less than or equal
to threshold - ∆ (1568), the output is 0. If your operational input is greater than
threshold + ∆ (1632), the output is 1:
While the input value is within the 2∆ band, it holds its last value.
For example, if the input value is increasing from a value less than or equal to 1568,
the output will be 0. When it exceeds 1632, the output rises to 1. If the input value
then begins to decrease after the output has risen to 1, the output will remain at 1
until the input value decreases to 1568, at which point it will drop to 0.
Note: To be valid, threshold + ∆ and threshold - ∆ must be a value in the range -
32,768 to +32,767.
1600 (threshold)
input value
1
0
-32 768
+32 767
output
1632
input value
1
0
-32 768
+32 767
output
1568