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Q
1
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H
L
2
D
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2
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D (transparent)
3
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4.11.6
Limit value
This software channel monitors the specified source channel. The result,
i.e. the output signal of the limit value channel, is "High" when the specified
alarm conditions are met.
The following forms of monitoring are available:
Mode
Alert when
Overrun
the value is above the specified range or above the
threshold
Underrun
the value is below the specified range or below the
threshold
Band mon-
itoring
the value is outside the specified range (threshold ±
bandwidth)
Band violation
the value is within the specified range (threshold ± band-
width)
Steady con-
dition
values change by more than the bandwidth
during lag
time.
In addition, you can also set no triggering for wire-breaks at the source.
The setting is only for sources (sensors) which can have wire-break mon-
itoring.
For all input, either enter a fixed value (
Manual value
) or specify a
chan-
nel
that delivers the value. It is possible to dynamically change the limit
values during measurement.
Threshold
is the decisive value in monitoring.
Hysteresis
: Hysteresis prevents the alarm being repeatedly activated for
small fluctuations around the threshold value in the monitored signal.
Depending on switch direction, the hysteresis lies below the threshold (for
overruns) or above the threshold (for underruns). See images. The hys-
teresis is especially beneficial for small (noise) signals. The
Delay
option
offers an alternative.
121
Delphin Technology AG
Januar 2018
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