Rockwell Automation 1761 MicroLogix 1000 Programmable Controllers - Manual (Page 145)

Using Math Instructions
8–13
The following example takes a 0V to 10V analog input from a MicroLogix 1000
analog controller and scales the raw input data to a value between 0 and 100%. The
input value range is 0V to 10V which corresponds to 0 to 31,207 counts. The scaled
value range is 0 to 100 percent.
Application Example – Convert Voltage Input to Percent
Scaled Value
(percent)
Input Value
0V 31,207 10V
100
(Scaled Max.)
(Scaled Min.)
(Input Min.) (Input Max.)
0
Calculating the Linear Relationship
Use the following equations to calculate the scaled units:
Scaled value = (input value x rate)
+
offset
Rate = (scaled max. – scaled min.) / (input max. – input min.)
= (100 – 0) / (31,207 –
0
)
= .00320 (or 32/10000)
Offset = scaled min. – (input min. x rate)
= 0
−
(0
Ч
.00320)
=
0