Beckhoff ELX3351, Руководство по эксплуатации

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Parameterization and programming
ELX3351 36 Version: 1.3.1
• IIR-Filter 1 to 8
The filter with IIR characteristics is a discrete time, linear, time invariant filter that can be set to eight
levels (level 1 = weak recursive filter, up to level 8 = strong recursive filter).
The IIR can be understood to be a moving average value calculation after a low-pass filter.
Fig. 29: Step response of the IIR filter
Note
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 measured value is available in each PLC cycle.
Note
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)
b1 = 1 - a
0