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Signal processing
7.2 Evaluation of universal inputs
7.2
Evaluation of universal inputs
7.2.1
Universal input evaluation overview
Essentially, the four universal inputs are evaluated according to the same principle, with the
only differences being in the signal names and/or the associated parameters.
The wiring and configuration (P.26 to P.29) should be adapted for the relevant signal type.
7.2.2
Evaluation of analog current signals
Relates to parameters
Parameter no.
P.26 to P.29
P.30 to P.33
Procedure
The analog current signal is changed by internal measurement resistance into a voltage that
is strengthened, filtered, and changed via an analog-digital exchanger into a digital signal.
This measured value passes through a low pass filter with a fixed time constant. The
measured value is then monitored for under and overflow, which is used to derive a fault
message if appropriate. The following standardization is performed depending on the setting
for the selected parameter:
P.*
0 to 20
4 to 20
20 to 0
20 to 4
66
Parameter name
Adjustment/display
range
"INP1" to "INP4"
0-20
4-20
20-0
20-4
"ALI1" to "ALI4"
-5.0% to 105.0%
0 %
0 mA
4 mA
20 mA
20 mA
Comment
Analog signal 0 to 20 mA->0 to 100%
Analog signal 4 to 20 mA->0 to 100%
Analog signal 20 to 0 mA->0 to 100%
Analog signal 20 to 4 mA->0 to 100%
Alarm for universal inputs 1 to 4
100%
20 mA
20 mA
0 mA
4 mA
SITRANS DA400 for oscillating positive displacement pumps
Operating Instructions, 09/2008, A5E00841120-03
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