Frequency Accuracy In High Resolution Frequency Mode; Calculate Frequency Accuracy - Allen-Bradley 1756-CFM User Manual

Frequency Accuracy in High
Resolution Frequency Mode
Frequency Accuracy
Use this appendix to calculate the frequency accuracy for High Resolution
Frequency mode and Totalizer mode.
There are two steps to calculating frequency accuracy in High Resolution
Frequency mode.

1. Calculate frequency accuracy.

2. Determine the application's operating conditions and add the error for
those conditions to the value obtained in step 1.
These values must be added to your frequency accuracy results in Totalizer
mode:
• Crystal error - 0.005% @ 25 °C
• Drift and crystal error - 0.01% from 0 °C to 60 °C
Calculate Frequency Accuracy
When calculating frequency accuracy in High Resolution Frequency mode, you
must know:
• sample time period
• input frequency
Use one of two equations to calculate the firmware error, in High Resolution
Frequency mode.
Rockwell Automation Publication 1756-UM010C-EN-P - June 2021
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