Rockwell Automation 1756-CFM ControlLogix Configurable Flowmeter Module - Manual (Page 142)

142 Rockwell Automation Publication 1756-UM010B-EN-P - December 2011
142 Frequency Accuracy
Use one of two equations to calculate the firmware error, in high resolution
frequency mode.
Choose the equation according to the frequency of your application.
 If your application has a frequency in the following range:
– 1Hz to 1/T
s
use the equation below:
 If your application has a frequency in the following range:
– greater than 1/T
s
to 120kHz
use the equation below:
EXAMPLE
Based on the equations listed above, if your application
uses a T
s
= 0.1 seconds, the “cut off ” frequency for
choosing an equation is 10Hz because 1/T
s
(or 1/0.1) =
10.
In other words, if your application uses a
T
s
= 0.1 seconds, for frequencies 1Hz to 10Hz, use the
following equation:
For frequencies greater than 10Hz to 1kHz, use the
following equation.
Accuracy =
F
in
40,000
Accuracy =
1
40,000
1
T
s
x
Accuracy =
F
in
40,000
Accuracy =
1
40,000
1
T
s
x