Linear scaling examples, Example 1: configuring a pressure sensor, Setup – Watlow MLS User Manual
Page 131
Linear Scaling Examples
MLS User’s Guide 119
Linear Scaling Examples
Example 1: Configuring a Pressure Sensor
You’re using a pressure sensor that generates a 4-20 milliamp signal.
The sensor generates 4 milliamps at 0.0 PSI and 20 mA at 50.0 PSI.
Setup
You connect the sensor to a loop input set up with a resistor scaling
network to produce 60 millivolts at 20 mA. (See the
Inputs
section of
Chapter 2: Installation
for more information on scaling networks.)
The sensor measures PSI in tenths, so the appropriate display format is -
999.9 to +3000.0.
This table shows the input readings.
Based on these input readings, use these scaling values:
PV
Displayed
Sensor Input
Reading (%FS)
50.0 PSI
20
100%
0.0 PSI
4
100%x(4ma/20 ma) = 20%
Parameter
Low Value
High Value
Process Value (PV)
0.0 PSI
50.0 PSI
Input Reading (RDG)
20.0
100.0