DVC6000f Series
March 2006
5-128
Figure 5-26. 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
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.
Advanced Features
The AI function block provided with the DVC6000f
provides added capability through the addition of the
following parameters:
ALARM_SEL—Allows one or more of the process
alarm conditions detected by the AI function block to
be used in setting its OUT_D [37] parameter.
OUT_D—Discrete output of the AI function block
based on the detection of process alarm condition(s).
This parameter may be linked to other function blocks
that require a discrete input based on the detected
alarm condition.
STDDEV and CAP_STDDEV— are diagnostic
parameters that can be used to determine the
variability of the process.
5
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