Reference Manual
748384-C
September 2003
Rosemount Analytical Inc. A Division of Emerson Process Management Analyzer Variables
2-39
NGA2000 Reference
NOXSPANGAS
Direction Bidirectional
Binding
None
Type
4-element floating point array
Value range
Typically 80% of RNGHI
Units ppm
Description
CLD only; contains the value of NOX span gases, element 1 containing the span gas
for range 1 etc.
Usage
During a span function, when in NOX mode, the analyzer adjusts the value of SPAN
for the selected range such that the value of PVA becomes equal to the value of the
appropriate element of NOSPANGAS, to within 0.02% of the range value. This
variable should be kept updated with the current value of the span gas as shown on
the bottle label. If the bottle is of dubious quality, it may be desirable to compare its
reading with that of a known good standard, and then mark the bottle and this variable
accordingly.
See also
SPAN
SPANWAS
OPSTATUS
Direction
Analyzer: bidirectional; 1/0 module: input
Binding
OPSTATUS
Type Enumerated
Value range
NORMAL; MAINTENANCE; STANDBY; CALIBRATION; QC CHECK.
Units None
Description
The current operational status of the analyzer.
Usage
Used to indicate the status of the module, so as to generate the appropriate relay
contact in the I/0 module.
NORMAL - normal operation.
MAINTENANCE - this analyzer's menus have been accessed.
STANDBY - the temperature or other parameters are not at normal levels.
CALIBRATION - the module is currently performing a zero, span or linearization
function.
QC CHECK - the variable PROCESS is set to a value greater than 0.
See also
GENERALSTATE
CALSTAT
PROCESS
OSC_TUNE
Direction Output
Binding
None
Type
Floating point
Value range
0-100
Units
Volt s
Description
NDIR only; the output of the oscillator coil.
Usage
It is necessary to detune the oscillator coil to about 80% of its peak reading, on the
higher frequency side of the peak. This allows the Luft detector to produce a linear
output as the measured gas concentration changes. Read this value as you first turn
the inductor core until you find the peak, then counter-clockwise past its peak until a
value of 80% of the peak value is reached.
See also
SIGNAL_GAIN
DET_SIG
RAW_SIGNAL