User guide

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

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

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⋅=

dnOut

Cycle

C04050: Filter time constant T

Filter

dnOut

Filter