SMC Networks PFCA7 Series Operation Manual page 58

○Conversion formula for process data and measurement/command value
(1) Conversion formula for process data to measurement/command value: Pr = a x (PD) + b
(2) Conversion formula for measurement/command value to process data: (PD) = (Pr – b) / a
Pr: Measurement value and command value
PD: Measurement value (process data)
A: Inclination
B: Intercept
[Inclination and intercept to the units specification]
Target Units
L/min
Instantaneous
flow
cfm
L
Accumulated
flow
Ft
[Calculation example]
(1) Conversion for process data to flow rate measurement/command value
(Range: 10 L/min; units specification: L/min; PD = 500)
Pr = a x (PD) + b
= 0.0025 x 500 + 0
= 1.25 [L/min]
(2) Conversion for flow rate measurement/command value to process data
(Range: 100 L/min; units specification: cfm; Pr = 2.0 [cfm])
(PD) = (Pr - b) / a
= [2.0 - (0)]/( 0.00088275)
≓ 2266
Range
10 L/min
25 L/min
50 L/min
100 L/min
10 L/min
25 L/min
50 L/min
100 L/min
10 L/min
25, 50, 100 L/min
10, 25, 50 L/min
3
100 L/min
Inclination a
0.0025
0.00625
0.0125
0.025
0.000088275
0.000220725
0.0004415
0.00088275
0.1
1
0.01
0.1
-58-
Intercept b
0
0
0
0
0
0
0
0
0
0
0
0
No.PF※※-OMA1002