Lenze E94A - Manual (Page 583)

Lenze · 9400 function library · Reference manual · DMS 6.7 EN · 08/2014 · TD05
583
5 Function blocks
5.168 L_TbDifferentiate - differentiator with low-pass filter
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5.168.1 Function
Considering the signalling technique, the FB consists of the series connection of a time-discrete dif-
ferentiator and a PT1 filter.
• The filtering of the output signal can be switched off with the setting of the filter time constant
T
Filter
to "0.001 s". In this case, the output signal results directly from:
[5-139] Formula for the output signal when the filter is switched off
[5-140] Step response when filter is switched off
• When the filter is switched on, each change of the input signal is evaluated with 1 s/T
Filter
. Then
the output signal tends to zero with the filter time constant T
Filter
:
[5-141] Step response when the filter is switched on
dnOut ΔdnIn
1 s
Task cycle time
--------------------------------------- ⋅
=
dnOut
t
T
Cycle
T
Cycle
1 s
C04050: Filter time constant T
Filter
dnOut
t
T
Filter
T
Filter
1 s