Function Blocks
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Function Block Reference Guide
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2.5 AI Function Block
Description
The
AI
label stands for
Analog Input
. This block is part of the
Loops
category. It looks like this
graphically on the Control Builder.
Function
Read value of an Analog Input from a specified real I/O address. Convert analog input value to
corresponding output (OUT) in engineering units based on the necessary scaling and conversions
performed.
LINEAR - converts analog input value to corresponding output in units based on a linear 0 to 100% scale
and specified high and low range values.
OUT = Scale x Input value + Bias
where:
Scale = High Range Value - Low range value
100
Input value = Analog Value in percent
T/C or RTD - converts analog input value in engineering units using the range of Input Type.
Note:
The failsafe detection on this input block configured for 4-20mA range is:
Low Detection: -3.2mA
High Detection: 21.6mA
Outside of the range the flag (Input Fail) is ON. There is no detection from 0 to 4 mA, but the
block continues to work and provide data which could be compared via an Alarm Block.
Input
•
Analog value from specified real I/O address.
Output
OUT = Analog Input value in engineering units.
FAIL = Digital status of channel
Digital Low (0) = OK
Digital High (1) = Open sensor or failed input channel.
Configuration Parameters
This is a view of the AI Properties Dialog
box.
You must configure the AI function block
parameters to the desired values or
selections that match your operating
requirements.
describes the parameters and the
value or selection.
Out