6. Function blocks
6.1 Manufacturer function blocks
6.1.2.2 CF - Frequency counter
General
easyE4 base devices provide 4 frequency counters
CF01…CF04. These high-speed frequency counters are intern-
ally connected with the digital inputs I01…I04 and operate
independently of the cycle time. The contacts will switch
according to the actual value.
Operating principle
For the entire configured measuring interval, the pulses at the input are counted inde-
pendently of the cycle time and are then used to determine the frequency. The num-
ber of pulses counted within the measuring interval is then provided as a value at
function block output QV. Finally, as a result, output QF delivers a value equal to ten
times the frequency so that the measurement can be accurate to the decimal place
despite the fact that the value range is of type integer.
This means that the frequency is the value at QF multiplied by 0.1.
F= QF*0.1
The value range cannot be exceeded as the maximum measured value is less than
the value range.
The CF01…CF04 frequency counters are not dependent on the cycle time.
The minimum counter frequency is 0 Hz.
The maximum counter frequency is 5 kHz.
Only square wave signals are permissible.
The mark-to-space ratio is 1:1.
The counter wiring must observe the following digital input assignment:
l
I01 counter input for frequency counter CF01
l
I02 counter input for counter CF02
l
I03 counter input for counter CF03
l
I04 counter input for counter CF04
Square wave count pulses are required to ensure a 1:1 mark to space
ratio.
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easyE402/24 MN050009ENEaton.com
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