CLS200 Series User’s Guide
Chapter 9: Linear Scaling Examples
160
Example 2: A 0-to-5VDC Sensor
Situation
A flow sensor connected to the controller measures the flow in a pipe. The sensor generates a 0 to
5V signal. The sensor’s output depends on its installation. Independent calibration measurements of
the flow in the pipe indicate that the sensor generates 0.5V at three gallons per minute (GPM) and
4.75V at 65 GPM. The calibration instruments are accurate to within 1 gallon per minute.
Setup
The sensor is connected to a loop input set up with a resistor voltage divider network producing
60mV at 5V. The INPUT TYPE for the loop is set to LINEAR. The calibrating instrument is precise
to ±1 GPM, so the DISP FORMAT is set to -999 to 3000.
This table shows the input readings and the percentage calculation from the 60mV full scale input.
Table 9.3 — Input Readings and Calculations
PROCESS VARIABLE
DISPLAYED
SENSOR INPUT
READING, PERCENT OF FULL SCALE
(%FS)
65 GPM 4.75 (4.75V / 5.00V) x 100%=95%FS
3 GPM 0.5 (0.5V / 5.00V) x 100%=10%FS
Table 9.4 — Scaling Values
PARAMETER PROMPT VALUE
High Process Variable
HIGH PV
65 GPM
High Sensor Reading
HIGH RDG
95.0%FS
Low Process Variable
LO PV
0.0 PSI
Low Sensor Reading
LO RDG
10.0%FS
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