Beckhoff EP3356-0022, Документация

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Commissioning/Configuration
EP3356-0022 34 Version: 1.4
Overview of conversion times
Filter Set-
tings Value PDO update
time Filter property Limit frequency
(-3 dB) [Hz]
(typ.) Comment Rise time 10-90 %
[s] (typ.)
Filter deacti-
vated - Cycle-synchro-
nous,, min.
100 µs - - - -
0 FIR 50 Hz 312.5 µs 50 Hz notch filter 22 Hz Typ. conversion
time 312.5 µs 0.013
1 FIR 60 Hz 260.4 µs 60 Hz notch filter 25 Hz Typ. conversion
time 260.4 µs 0.016
2 IIR1 Cycle-synchro-
nous (up to min.
100 µs) Low-pass 2000 Hz a
0
=1/2
1
= 0.5 0.0003
3 IIR2 Low-pass 500 Hz a
0
=1/2
2
= 0.25 0.0008
4 IIR3 Low-pass 125 Hz a
0
=1/2 4 = 62.5e-
3
0.0035
5 IIR4 Low-pass 30 Hz a
0
=1/2
6
= 15.6e-
3
0.014
6 IIR5 Low-pass 8 Hz a
0
=1/2
8
= 3.91e-
3
0.056
7 IIR6 Low-pass 2 Hz a
0
=1/2
10
= 977e-
6
0.225
8 IIR7 Low-pass 0.5 Hz a
0
=1/2
12
= 244e-
6
0.9
9 IIR8 Low-pass 0.1 Hz a
0
=1/2
14
= 61.0e-
6
3.6
10 Dynamic IIR The filter changes dynamically between the filters IIR1 to IIR8
11 PDO Filter fre-
quency 1/PDO
Value[Hz]*64 Notch filter with
adjustable fre-
quency ca. 0,443 * PDO
Value [Hz] - -
Filter and cycle time
If the FIR filters (50 Hz or 60 Hz) are switched on, the process data are updated maximally with the
specified conversion time (see table). The IIR filter works cycle-synchronously. Hence, a new mea-
sured value is available in each PLC cycle.
At which point the filters can be adjusted is described in the chapter “Object description and
parameterization” for example under index 0x8000:12.
IIR filter
Differential equation: Y
n
= X
n
* a
0
+ Y
n-1
* b
1
with a
0
+ b
1
= 1
a
0
= (see table), b
1
= 1 - a
0
Dynamic IIR Filter
The dynamic IIR filter automatically switches through the 8 different IIR filters depending on the weight
change. The idea:
• The target state is always the IIR8-Filter, i.e. the greatest possible damping and hence a very calm
measured value.
• In the input variable changes rapidly the filter is opened, i.e. switched to the next lower filter (if still
possible). This gives the signal edge more weight and the measured value curve can follow the load
quickly.
• If the measured value changes very little the filter is closed, i.e. switched to the next higher filter (if still
possible). Hence the static state is mapped with a high accuracy.
• The evaluation as to whether a downward change of filter is required or whether an upward change is
possible takes place continuously at fixed time intervals.
Parameterization takes place via the CoE entries 0x8000:13 and 0x8000:14 [
}
66] . Evaluation takes place
according to 2 parameters:
• The "Dynamic filter change time" object (0x8000:13) [
}
66] is used to set the time interval at which the
existing signal is re-evaluated.