Example 2: configuring a flow sensor, Setup – Watlow MLS User Manual
Page 132
120 MLS User’s Guide
Linear Scaling
Example 2: Configuring a Flow Sensor
You connect a flow sensor to the MLS to measure the flow in a pipe.
The sensor generates a 0-5V signal. The sensor's output depends on its
installation. Measurements of the flow in the pipe indicate that the
sensor generates 0.5 volts at three gallons per minute (GPM) and 4.75
volts at 65 GPM. The calibration instruments are precise to +1 gallon
per minute.
Setup
The sensor is connected to a loop input set up with a resistor voltage
divider network to produce 60 millivolts at 5 volts. (See the
Inputs
section of the
Installation
chapter for information on scaling networks.)
The calibrating instrument is precise to ñ1 gallon per minute, so the
appropriate display format is -999 to +3000.
This table shows the input readings.
Based on these input readings, use these scaling values:
PV
Displayed
Sensor Input
Reading (%FS)
65 GPM
4.75
(4.75V / 5.00V) x 100%=95%
3 GPM
0.5
(0.5V / 5.00V) x 100%=10%
Parameter
Low Value
High Value
Process Value (PV)
3 GPM
65 GPM
Input Reading (RDG)
10.0
95.0