Rockwell Automation 1746-NI16V SLC 500 Analog Input Modules User Manual - Manual (Page 61)

Publication 1746-UM001A-US-P
Channel Configuration, Data, and Status 5-13
Engineering Units to Real Units
Example #1: A transducer is being used to measure temperature.
The 4 to 20 mA signal is proportional to 100 to 500°C (212 to 932°F).
The input data is in engineering units, i.e. 4 to 20 mA
where
and
Input value to convert = 5500
The scaled range is 212 to 932°F
The input range is 4000 to 20000
Find: Input Value in °F.
Per the equations above:
Example #2: A transducer is being used to measure temperature.
The 0 to 10V dc signal range is proportional to 0 to 10°C.
The input data is in engineering units, i.e. 0 to 10V dc
where
Input value to convert = 5000.
Find: Input value in °C.
Per the equations above:
4mA
1
µ
A per step
----------------------------------- 4000 =
20mA
1
µ
A per step
----------------------------------- 20000 =
Slope
932 212 –
( )
20000 4000 –
( )
-----------------------------------------
·
0.045
·
= =
Offset 212 4000 0.045
× ( )
32 = – =
Scaled Value 5500 0.045
× ( )
32 279.5
°
F = + =
10Vdc
1mV per step
----------------------------------- 10000 =
Slope
10 0 –
( )
10000 0 –
( )
-------------------------------- 0.001 = =
Offset 0 0 0.001
× ( )
0 = – =
Scaled Value 5000 0.001 5
°
C =
Ч
=