Watlow CLS200 - Manual (Page 207)

CLS200 Series User’s Guide Chapter 10: Linear Scaling Examples
Doc.# 0600-3050-2000 Watlow Anafaze 191
Example 2: A 0-to-5VÎ (dc) Sensor
Situation
A flow sensor connected to the controller measures the flow
in a pipe. The sensor generates a 0 to 5V signal. The sen-
sor’s output depends on its installation. Independent cali-
bration 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 resis-
tor voltage divider network producing 60mV at 5V.
The INPUT TYPE for the loop is set to LINEAR. The calibrat-
ing 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 10.3 Input Readings and Calculations
Table 10.4 Scaling Values
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
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 GPM
Low Sensor Reading LO RDG 10.0%FS