MATH.MeasureFrequence (FB)

(CAA_Mathematics.library)

This function block will measure the average frequency of an input signal over a defined number of periods. The function block being able to return a correct result it has to be called with a frequency higher than the maximum frequency of the input signal.

Input:

xEnable	BOOL	reset (see ⇘ “CAA 指南”)
xInput	BOOL	input signal
usiPeriods	USINT(1..10)	number of time periods the frequency shall be averaged in ( number

Output:

lrFrequency	LREAL	averaged frequency ( in Hz)
xValid	BOOL	validity of result; will be set to FALSE, if the required number of time periods has not yet been passed or if the distance in time of two raising edges exceeds 3*lrFrequency