Wiring with the logic relay
120
1SVC 440 795 M0100
The frequency counter allows you to enter an upper
threshold value as a comparison value. The C15 and C16
frequency counters are not dependent on the cycle time.
Counter frequency and pulse shape
The maximum counter frequency is 1 kHz.
The minimum counter frequency is 4 Hz.
The signals must be square waves. We recommend a mark-
to-space ratio of 1:1.
If this is not the case:
The minimum mark-to-space ratio is 0.5 ms.
t
min
= minimum time of the pulse or pause duration
f
max
= maximum count frequency (1 kHz)
Measurement method
The pulses on the input are counted for one second
irrespective of the cycle time, and the frequency is
determined. The measurement result is provided as an actual
value.
Wiring of a frequency counter
The digital inputs have the following assignment:
• I3 counter input for frequency counter C15.
• I4 counter input for frequency counter C16.
t
min
= 0.5 x
1
f
max
h
Frequency counters operate independently of the program
cycle time. The result of the actual value setpoint
comparison is only transferred once every program cycle
for processing in the circuit diagram.
The reaction time in relation to the setpoint/actual value
comparison can therefore be up to one cycle in length.
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