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Instruction Manual
IM-106-880C, OI
September 2009
7-27
Hazardous Area OCX 8800
You can 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).
PV = Channel Value
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 flowmeters.
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.
Block Errors Table 7-20 lists conditions reported in the BLOCK_ERR parameter.
Conditions in italics are inactive for the AI block and are given here only for
your reference.
FIELD_VAL
100 x (Channel Value – EU*@0%)
(EU*@100% – EU*@0%)
=
* XD_SCALE values
38740082
PV
FIELD_VAL
100
x (EU**@100% – EU**@0%)+ EU**@0%=
** OUT_SCALE values
38740083
PV
FIELD_VAL
100
x (EU**@100% – EU**@0%)+ EU**@0%=
** OUT_SCALE values
38740084