Eaton easy500, easy700

4 Wiring  with
4.6 High-speed counters, -DA, -DC
100 Operating instructions 05/10 MN05013003Z-EN www.eaton.com
4.6 High-speed counters, -DA, -DC
easy provides various high-speed counter functions. These counter function
blocks are coupled directly to digital inputs. The following functions are
possible:
• Frequency counters: C15 and C16
• High-speed counters: C13 and C14.
4.6.1 Frequency Counter
easy provides two frequency counters C15 and C16 for use as required. The
frequency counters can be used for measuring frequencies. The high-speed
frequency counters are permanently connected to the digital inputs I3 and I4.
Applications such as speed monitoring, volume measurement using a
volume counter, the monitoring of machine running can be implemented
with the frequency counter.
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.
4.6.1.1 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)
4.6.1.2 Measuring procedure
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.
t
min
= 0.5 x
1
f
max
￫
The 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.