Measured value smoothing
You will find information that is generally applicable to the smoothing of analog values in the
respective section. You can only set strong smoothing for the SM 431; AI 8 x 14 Bit.
The module cycle time is a constant, irrespective of how many channels are enabled. It
therefore has no effect on the filter settling time, which is defined by the parameter assignment
of interference frequency suppression and smoothing.
Filter settling time with strong smoothing
Table 5-54
Interference frequency suppression and filter settling time with smoothing
Noise suppression
Smoothing
Filter settling time in ms
None
Strong
-
50 Hz
Strong
100
60 Hz
Strong
83,333
400 Hz
Strong
12,5
Step response with strong smoothing
The following figure illustrates the contents of the table above. It shows the filter settling time
after which, in the case of a step response, the smoothed analog value is applied to almost
100%, depending on the interference frequency suppression that has been set. The figure
applies to every change of signal at an analog input.
50
100
0
63
60 Hz:
50 Hz:
120
30
150
60
12,5
83,333 100
400 Hz:
Signal variation
in percent
Step response for any analog input signal
Noise suppression
Filter settling time in ms
Figure 5-29 Step response of the SM 431; AI 8 x 14 Bit (6ES7 431-1KF20-0AB0)
Analog modules
5.21 Analog input module SM 431; AI 8 x 14 Bit (6ES7431-1KF20-0AB0)
S7-400 Automation System Module Data
260
Reference Manual, Ausgabe 11/2016, A5E00850736-08