Emerson NGA2000 Reference Manual page 95

NGA2000 Reference
LIN_UNDER
Direction
Binding
Type
Value range
Units
Description
Usage
See also
LIN_UNITS
Direction
Binding
Type
Value range
Units
Description
Usage
See also
LIN_VAR_ID
Direction
Binding
Type
Value range
Units
Description
Usage
See also
LINA0_
LINA1_, LINA2_, LINA3_, LINA4_
Direction
Binding
Type
Value range
Units
Description
Usage
See also
Rosemount Analytical Inc. A Division of Emerson Process Management
Bidirectional
None
4-element floating point array
0 - 100; normally 5
Percent
The amount less than the linearization range over which this curve is valid.
LIN_OVER.and LIN_UNDER shows how far negative the signal can go before the
input/output relationship becomes linear with slope equal to the slope at zero. It is
expressed in percent of the linearization range given by LINRNGHI.
Other LINxxxxxxxx variables
Bidirectional
LIN_UNITS
Enumerated
Percent of span gas, ppm
None
Allows the user to express the gas concentration as a percentage of the span gas or
as an absolute value in ppm
Allows the user to dilute a span gas, and therefore to avoid having to re-enter all 20
gas values when he changes his span gas
Bidirectional
LIN_UNITS
Enumerated
Point 1 to Point 20
None
Allows the user to specify which gas sample he is entering
Controls the self-linearization measurement.
Bidirectional
None
4-element floating point array
Sum of each set of elements must be 1.0 ± 0.02.
None
Linearizer coefficients. Each element applies to the range given by that element
number, so LINAO-1 is the zeroth coefficient for range 1.
NGA analyzers use a fourth order polynomial to linearize the normalized output of
the sensors. The input range to the polynomial covers 0 - 1, and the output should
cover that range as well. In general, the curve passes through the points (0,0) and
(1.0,1.0), within the limits of acceptable error, usually 2%, i.e. ± 0.02 to 1.0 ± 0.02.
These coefficients may be written to as desired, although Rosemount cannot
guarantee linearization specifications if locally produced values are used. It is
essential that the polynomial produced be monotonic over the range of 0 - 1,
otherwise the calibration routines may fail.
Other LINxxxxxxxx variables
Reference Manual
748384-C
September 2003
Analyzer Variables 2-33