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52 ANASCAN User’s Guide

APPENDIX: Input Scaling

This table shows the input readings.

The scaling values are therefore:

Example 2

Situation

A flow sensor connected to the CAS measures the flow in a pipe. The

sensor generates a 0-5V signal. The sensor's output depends on its

installation. Independent calibration measurements of the flow in the

pipe indicate that the sensor generates 0.5 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 channel 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 ±1 gallon per minute, so the

appropriate display format is -999 to +3000.

This table shows the input readings.

The scaling values are therefore:

Example 3

Situation

Displayed

Sensor Input Reading (%FS)

50.0 psi 20 100%

0.0 4 100% x (4ma/20ma) = 20%

Parameter Low Value High Value

Process Value (PV) 0.0 psi 50.0 psi

Input Reading (RDG) 20.0 100.0

Displayed

Sensor Input Reading (%FS)

65 GPM 4.75 (4.75 V/ 5.00 V) x 100% = 95%

3 GPM 0.5 (0.5 V/ 5.00 V) x 100% = 10%

Parameter Low Value High Value

Process Value (PV) 3 GPM 65 GPM

Input Reading 10.0 95.0

1 2 ... 55 56 57 58 59 60 61 62

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Watlow ANASCAN Manual de usuario Pagina 60