Rockwell-automation 1756-CFM ControlLogix Configurable Flowmeter Modul Uživatelský manuál stáhnout pdf (Strana 144)

144Rockwell Automation Publication 1756-UM010B-EN-P - December 2011

144 Frequency Accuracy

Use the following equation to calculate frequency accuracy in totalizer mode

for frequency period:

Speed

For speed, you must know the filter resolution. Use the following equation to

calculate frequency accuracy in totalizer mode for speed:

EXAMPLE

For example, in an application with the following

conditions:

 0.5s time period

 123Hz frequency

 25°C operating temperature

accuracy is determined with the following equation:

EXAMPLE

For example, in an application with the following

conditions:

 0.001 filter resolution

 25°C operating temperature

accuracy is determined with the following equation:

Accuracy =

(1) x (100)

) x (F

)

Accuracy =

(1) x (100)

(0.5) x (123)

Accuracy = 1.626 + 0.005

+ 0.005%

Accuracy = +/- 1.631%

Value is added to

accuracy to account

for the crystal error

Accuracy = Resolution x 100

Accuracy = 0.1 + 0.005

Accuracy = (0.001 x 100) + 0.005

Accuracy = +/- 0.105%

Value is added to

accuracy to account

for the crystal error

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Rockwell-automation 1756-CFM ControlLogix Configurable Flowmeter Modul Uživatelský manuál Strana 144