Emerson Rosemount 2240S, Reference Manual, Page: 171 / 194

161
F
OUNDATION
™
Fieldbus Block Information
F
OUNDATION
™
Fieldbus Block Information
October 2017
Reference Manual
00809-0100-2240, Rev DA
C.2 Analog input block
Figure C-1. Analog Input Block
The Analog Input (AI) function block processes field device measurements and makes them available to
other function blocks. The output value from the AI block is in engineering units and contains a status
indicating the quality of the measurement. The measuring device may have several measurements or
derived values available in different channels. Use the channel number to define the variable that the AI
block processes.
The AI block supports alarming, signal scaling, signal filtering, signal status calculation, mode control,
and simulation. In Automatic mode, the block’s output parameter (OUT) reflects the process variable
(PV) value and status. In Manual mode, OUT may be set manually. The Manual mode is reflected on the
output status. A discrete output (OUT_D) is provided to indicate whether a selected alarm condition is
active. Alarm detection is based on the OUT value and user specified alarm limits. Table C-1 lists the AI
block parameters and their units of measure, descriptions, and index numbers.
Figure C-2. Analog Input Function Block Schematic
OUT=The block output value and status
OUT_D=Discrete output that signals a selected alarm condition
OUT_D
AI
OUT
Analog Measurement
Access
Analog
Meas.
CHANNEL
SIMULATE
OUT_SCALE
XD_SCALE
FIELD_VAL
L_TYPE
IO_OPTS
PV_FTIME
MODE
STATUS_OPTS
HI_HI_LIM
HI_LIM
LO_LO_LIM
LO_LIM
ALARM_HYS
ALARM_TYPE
OUT_D
OUT
PV
Convert
Cutoff Filter
Status
Calc.
Alarm
Detection
NOTES:
OUT = block output value and status.
OUT_D = discrete output that signals a selected alarm condition.
LOW_CUT