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Reference Manual
00809-0200-4101, Rev AA
July 2008
Rosemount 2051
3-9
Solution
Table 3-5 lists the appropriate configuration settings.
Table 3-5. Analog Input
Function Block Configuration for
a Differential Pressure
Transmitter.
Filtering The filtering feature changes the response time of the device to smooth
variations in output readings caused by rapid changes in input. Adjust the
filter time constant (in seconds) using the PV_FTIME parameter. Set the filter
time constant to zero to disable the filter feature.
Figure 3-3. Analog Input
PV_FTIME filtering Diagram.
Low Cutoff When the converted input value is below the limit specified by the LOW_CUT
parameter, and the Low Cutoff I/O option (IO_OPTS) is enabled (True), a
value of zero is used for the converted value (PV). This option is useful to
eliminate false readings when the differential pressure measurement is close
to zero, and it may also be useful with zero-based measurement devices such
as flowmeters.
NOTE
Low Cutoff is the only I/O option supported by the AI block. Set the I/O option
in Manual or Out of Service mode only.
Parameter Configured Values
L_TYPE Indirect Square Root
XD_SCALE 0 to 20 in.H
2
O
OUT_SCALE 0 to 800 gal/min.
Channel 1 - pressure
Out
PV XDSCALE0–
XDSCALE100
-------------------------------------------------
OUTSCALE100 OUTSCALE0–()OUTSCALE0+=
OUT
8inH
2
O0inH
2
O–
20inH
2
O0inH
2
O–
------------------------------------------------------
=
(800gal/min. - 0gal/min.) + 0gal/min. = 505.96gal/min.
PV_FTIME
63% of Change
OUT (mode in man)
OUT (mode in auto)
PV
Time (seconds)
FIELD_VAL