Function Blocks
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Function Block Reference Guide
103
2.37 MMA Function Block,
continued
Function,
continued
•
If DEV configured > 0, then
:
– the standard deviation is calculated for the number of inputs connected to the
block, and SDEV = result;
– any inputs that deviate more than the configured number (DEV) of standard
deviations from the average are not used to
calculate the MIN, MAX, AVG, and SUM outputs;
– if any input deviates more than the configured number (DEV) of standard
deviations, ALM turns ON;
– if all inputs deviate more than the configured number (DEV) of standard
deviations, then the;
– MIN, MAX, AVG, and SUM outputs all equal zero (0), and ALM turns ON.
•
Standard Deviation (SDEV) =
i = n
∑
i = 1
n
(X - X)
2
i
where:
X= AVG
n = the number of connected inputs
.
Input
Xl = First analog value.
X2 = Second analog value.
X3 = Third analog value.
X4 = Fourth analog value.
X5 = Fifth analog value.
X6 = Sixth analog value.
Output
MIN
= Calculated minimum analog value.
MAX
= Calculated maximum analog value.
AVG
= Calculated average of analog values.
SU
= Calculated sum of analog values.
SDEV
= Square root of Z divided by N, where Z = the sum of individual squared deviations from the
average of the first n inputs.
ALM
= Digital signal for alarm indication.