Emerson Rosemount 848T, Reference Manual, Page: 119 / 136

109
Reference Manual
00809-0100-4697, Rev GA
Appendix D: Function Blocks
November 2014
Function Blocks
Figure D-4. Multiple 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 (same value applied to eight channels). 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. 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).
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 and OUT
parameters.
OUT_1
OUT_2
OUT_3
OUT_4
OUT_5
OUT_6
OUT_7
OUT_8
OUT_SCALE XD_SCALE
Mode Logic
L_TYPE &
Filter
Ch 1
Ch 2
Ch 3
Ch 4
Ch 5
Ch 6
Ch 7
Ch 8
Sim
u
la
te
PV Channel Value =
PV
Channel Value
100
--------------------------------------
 
 
EU**@100% EU**@0%
–
( )
EU**@0% + ¥ =
** OUT_SCALE values
PV
Channel Value
100
--------------------------------------
 
 
EU**@100% EU**@0%
– ( )
EU**@0% + ¥ =
** OUT_SCALE values