Emerson Fisher FIELDVUE DVC6000f, Instruction Manual

Page: 191 / 384

AI Function Block
December 2009 4-131
Figure 4-26. Analog Input Function Block Schematic
ANALOG
MEASUREMENT
ACCESS
ANALOG
MEAS.
CHANNEL
SIMULATE
CONVERT STATUS
CALC.
OUT_D
OUT
PV
ALARM
DETECTION
ALARM_TYPE
ALARM_HYS
LOW_CUT
HI_HI_LIM
HI_LIM
LO_LO_LIM
LO_LIM
OUT_SCALE
XD_SCALE
FIELD_VAL
IO_OPTS
STATUS_OPTS
CUTOFF FILTER
PV_FTIME
L_TYPE
MODE
NOTES:
OUT
_D = BLOCK OUTPUT VALUE AND STATUS
OUT_D = DISCRETE OUTPUT THAT SIGNALS A SELECTED ALARM CONDITION.
FIELDBUS-FBUS_02A
You can choose from direct, indirect, or indirect
square root signal conversion with the L_TYPE [16]
parameter.
Direct
Direct signal conversion allows the signal to pass
through the accessed channel input value (or the
simulated value when simulation is enabled).
PV = Channel Value
Indirect
Indirect signal conversion converts the signal linearly
to the accessed channel input value (or the simulated
value when simulation is enabled) from its specified
range (XD_SCALE [10]) to the range and units of the
PV [7] and OUT [8] parameters (OUT_SCALE [11]).
X (EU **@100%
−
EU **@0%) + EU **@0%
**OUT_SCALE values
PV =
100
( )
FIELD_VAL
Indirect Square Root
Indirect Square Root signal conversion takes the
square root of the value computed with the indirect
signal conversion and scales it to the range and units
of the PV [7] and OUT [8] parameters.
PV = FIELD_VAL
X (EU **@100%
−
EU **@0%) + EU **@0%
100
)
(
**OUT_SCALE values
When the converted input value is below the limit
specified by the LOW_CUT [17] parameter, a value of
zero is used for the converted value (PV [7]). This
option is useful to eliminate false readings when the
differential pressure measurement is close to zero.
Note
Invert is the only I/O option supported
by the AI block. You can set the I/O
option in Out of Service mode only.
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