Rockwell Automation 1746-NI16V SLC 500 Analog Input Modules User Manual - Manual (Page 63)

Publication 1746-UM001A-US-P
Channel Configuration, Data, and Status 5-15
1746-NI4 Data Format Units to Real Units
Example: #5 A transducer is being used to measure flow rate.
The -10V dc to +10V dc signal range is proportional to 0 to 100 GPM
The input data is in “1746-NI4” format, i.e. input range of -32768 to 32767
Input value to convert = 10000
The Scaled range is 0 to 100 GPM
The Input range is -32768 to +32767
Find: Input value in GPM
Per the equations above:
User-Defined Scaling Data Format to Real Units
Example: #6 A transducer is being used to measure pressure.
The -10V dc to +10V dc signal range is proportional to 0 to 200 psi
The input data is in “User Defined Format”, where:
The lower input limit (configuration word 8) = 0
The upper input limit (configuration word 9) = 20000
Input value to convert = 16600
Scaled range is 0 to 200 psi
Input range is 0 to 20000
Find: Input value in psi
Per the equation above:
Slope
100 0 –
( )
32767 32768 –
( )
–
[ ]
------------------------------------------------------ 0.0015 = =
Offset 0 32768 – 0.0015
× ( )
49.15 = – =
Scaled Value 10000 0.0015
× ( )
49.15 64.15 GPM = + =
Slope
200 0 –
( )
20000 0 –
( )
-------------------------------- 0.01 = =
Offset 0 0 0.01
× ( )
0 = – =
Scaled Value 16600 0.01 166 psi =
Ч
=