Precision Digital PD941 - Manual (Page 26)

ConsoliDator Multi-Channel Controller Instruction Manual
26
Square Root
Square root mode refers to 2-point scaling with square root extraction typically used to
linearize the signal from a differential pressure transmitter and display the flow rate in
engineering units. The graph in Figure 18 shows the display response based on
example scaling parameters. For this mode select [Square Root] from Function
options.
The square root mode supports low-flow cutoff which can be used to suppress
readings below a programmed value. Below the cutoff value, the controller will display
“0”. To enter a cutoff value, select Configure Function Parameters. Press EDIT and
use arrow keys to change the value. Press SAVE when complete.
Follow Sensor Input Setup (page 29) to enter your scaling parameters.
Note: An input that goes below the Low Value parameter results in a display of “-999999”
indicating underrange condition. This can be prevented using the cutoff feature.
Process Scaling Parameters
Input
(mA)
Display
(%)
High Value: 100.00 Low Value: 0.00
4.00 0.00 Sensor: 20.00 Sensor: 4.00
5.00 25.00
Squa re Root Re sponse
0.00
20.00
40.00
60.00
80.00
100.00
4.00 8.00 12.00 16.00 20.00
Sensor (mA)
Display (%
)
6.00 35.36
7.00 43.30
8.00 50.00
9.00 55.90
10.00 61.24
11.00 66.14
12.00 70.71
13.00 75.00
14.00 79.06
15.00 82.92
16.00 86.60
17.00 90.14
18.00 93.54
19.00 96.82
20.00 100.00
Figure 18. Square Root Response Graph