Watlow Series D8 - Manual (Page 108)

Chapter 4: Operation and Setup Series D8 User’s Guide
90 Watlow Anafaze Doc. 0600-3120-2000
•
Input signal high
= 20 mA/20 mA = 1.0 = 100%
• For the Input range low and Input range high parameters,
enter the process values that correspond to the low and
high signals. In this case, a 20 percent (4 mA) signal rep-
resents 0.0 PSI. A 100 percent (20 mA) signal represents
50.0 PSI.
Table 4.4 Input Readings
Table 4.5 Scaling Values
Input Scaling Example: 0 to 5 Vdc Sensor
Situation
A flow sensor connected to the controller measures the flow
in a pipe. The sensor generates a 0 to 5 Vdc signal. Indepen-
dent calibration measurements of the flow in the pipe indicate
that the sensor generates 0.5 V at 3 gallons per minute (GPM)
and 4.75 V at 65 GPM. The calibration instrument is accurate
±1 GPM.
Setup
For the Disp format parameter in the Input menu, choose
-999to 3000
, because the calibrating instrument is precise to
±1 GPM.
The tables below show the minimum and maximum input sig-
nals and their corresponding process variables, and the result-
ing values for the scaling parameters.
Process
Variable
Displayed
Sensor
Input
Reading in
Percent of Full Scale
50.0 PSI 20 mA 100%
.0 PSI 4 mA 100% x (4 mA/20 mA) = 20%
Parameter Value
Input range high 50.0 PSI
Input high signal 100.0%
Input range low .0 PSI
Input low signal 20.0%