
n
Here you can specify a time interval for the setting of the
Steady State
bit
(DMS_STAT-Bit 1).
n
If the measured value is within the tolerance window SST longer than the time interval
SSW, then bit 1 of the status word DMS_STAT is set.
Byte
Bit 7 ... 0
0...3
Reference load for the calibration
n
Here you can specify the reference load for the calibration unit-free. The reference
load must be at least 20% of the
Nominal load
NL.
3.16.6
Deployment of the filter functions
The module has the following filter functions, which can be activated via the parametriza-
tion:
n
FIR 50/60 Hz
n
Dynamic IIR filter
n
Static IIR filter
In the parametrization via FILT you can specify the filter
FIR 50 Hz
respectively
FIR 60
Hz
. These filters acts a notch filter. Notch filter generate at the configured frequency and
the multiple thereof zeros (notches) in the frequency response. They attenuate these fre-
quencies here in the amplitude. When filters are used, these influence the conversion
time of your module. The higher the filter frequency, the faster the conversion time. This
can be used for the suppression of mains frequency interferences.
n
By activation of the dynamic IIR filter in the FILT parameter, dependent on the current
weight change, it is automatically switched between 8 different filters. The aim here is
to obtain a filter with the best possible damping, which must lead to stable measuring
values. The
Dynamic IIR filter
acts as 1. order low-pass filter and has the following
properties:
–
If there is a rapid change of the input value, it is switched-over to the next lower
filter (e.g. IIR1
à
IIR2). In this way the load changes are less precise, but it is
faster recognized.
–
If there is small change in the measured value, it is switched-over to the next
higher filter (e.g. IIR2
à
IIR1), so you will get a higher precision.
–
With the IIR1 filter you get the lowest noise suppression and the most unstable
measured value.
–
With the IIR8 filter you get the highest noise suppression and the most stable
measured value.
–
The revaluation, which can lead to a modification of the filter levels, takes place in
a fixed interval, which can be specified via parameter
DFCT
in ms.
Filter level
Limit frequency
Filter constant
Rise time 10-90% [s]
(typ.)
02h: IIR1
1000
a
0
= 0.5
0.0003
03h: IIR2
500Hz
a
0
= 0.25
0.0008
04h: IIR3
125Hz
a
0
= 62.5x10
-3
0.0035
05h: IIR4
30Hz
a
0
= 15.6x10
-3
0.014
RL Reference load
Overview
FIR 50/60 Hz
Dynamic IIR filter
VIPA System SLIO
Analog Input
031-1CA20 - AI 1x16(24)Bit Strain gauge (DMS) > Deployment of the filter functions
HB300 | SM-AIO | | en | 17-05
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