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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/Ts
use the equation below:
Accuracy =
Fin
40,000
 If your application has a frequency in the following range:
– greater than 1/Ts to 120kHz
use the equation below:
Accuracy =
EXAMPLE
1
Ts
x
1
40,000
Based on the equations listed above, if your application
uses a Ts = 0.1 seconds, the “cut off ” frequency for
choosing an equation is 10Hz because 1/Ts (or 1/0.1) =
10.
In other words, if your application uses a
Ts = 0.1 seconds, for frequencies 1Hz to 10Hz, use the
following equation:
Accuracy =
Fin
40,000
For frequencies greater than 10Hz to 1kHz, use the
following equation.
Accuracy =
1
Ts
x
1
40,000
142Rockwell Automation Publication 1756-UM010B-EN-P - December 2011