Rockwell Automation DeviceLogix System User Manual - Manual (Page 36)

36 Publication RA-UM003B-EN-P - February 2010
Chapter 2 Navigate the Function Block Editor Interface
Statistical Category
The Statistical category includes a single instruction type: Moving
Average.
Moving Average
The DeviceLogix Moving Average function block calculates a time
average value for the input signal.
When sampling is enabled, the object executes this formula as the
main function.
When the object starts executing, the moving average is initialized, as
shown in the example that follows.
Example
Number of samples = 3
Scan 1: Output1 = Input1
Scan 2: Output2 = (Input2+Input1)/2
Scan 3: Output3 = (Input3+Input2+Input1)/3
The table lists the conditions and corresponding output with special
input values.
IMPORTANT
When data values are large, switching between REAL and DINT
data types may cause a minimal loss of accuracy. For example,
a value of 99999999 DINT will be rounded up to 100000000
REAL when you switch to a REAL data type and then back to a
DINT data type.
Condition
Output
Fault Code
Fault Option = 1 Fault Option = 2 Fault Option = 3
INPUT in NAN NAN Hold last output Value of instance
attribute Fault State
Value 2
INPUT is the Positive
Infinity Positive Infinity 2
INPUT is the Negative
Infinity Negative Infinity 2
Input value from
binding source is out
of range for the object The calculated result
using the truncated input
value 1