Emerson Rosemount 848T, Reference Manual, Page: 111 / 136

101
Reference Manual
00809-0100-4697, Rev GA
Appendix D: Function Blocks
November 2014
Function Blocks
Figure D-2. Analog Input Function Block Schematic
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.
Signal conversion
Set the signal conversion type with the Linearization Type (L_TYPE) parameter. View the
converted signal (in percent of XD_SCALE) through the FIELD_VAL parameter.
Choose from direct, indirect, or indirect square root signal conversion with the L_TYPE
parameter.
Direct
Direct signal conversion allows the signal to pass through the accessed channel input value (or the
simulated value when simulation is enabled).
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) to the range
and units of the PV and OUT parameters (OUT_SCALE).
OUT = Block output value and status
OUT_D = Discrete output that signals a selected alarm condition
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
ALM_SEL
OUT_D
OUT
PV
Convert
Cutoff Filter
Status
Calc.
Alarm
Detection
LOW_CUT
F
FIELD_VAL
100 Channel Value EU*@0%
– ( )
¥
EU*@100% EU*@0%
–
( )
----------------------------------------------------------------------------------------- =
* XD_SCALE values
PV Channel Value =
PV
FIELD_VAL
100
----------------------------
 
 
EU**@100% EU**@0%
– ( )
EU**@0% + ¥ =
** OUT_SCALE values