Emerson Rosemount 2240S, Справочное руководство, Страница: 87 / 194

77
Reference Manual
00809-0100-2240, Rev DA
Configuration/Operation
October 2017
Configuration/Operation
5.10.6 Signal Conversion
You can set the signal conversion type with the Linearization Type (L_TYPE) parameter. You can view the
converted signal (in percent of XD_SCALE) through the FIELD_VAL parameter.
You can choose from direct or indirect 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.
When the converted input value is below the limit specified by the LOW_CUT parameter, and the Low
Cutoff I/O option (IO_OPTS) is enabled (True), a value of zero is used for the converted value (PV). This
option is useful to eliminate false readings when the differential pressure measurement is close to zero,
and it may also be useful with zero-based measurement devices such as flow meters.
Note
Low Cutoff is the only I/O option supported by the AI block. You can set the I/O option in Manual or Out
of Service mode only.
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
PV
FIELD_VAL
100
-------------------------------
 
 
EU**@100% EU**@0% –
 
EU**@0% +

=
** OUT_SCALE values