Emerson NGA2000 Reference Manual page 109

NGA2000 Reference
PVACEMS
Direction
Binding
Type
Value range
Units
Description
Usage
See also
PVU
Direction
Binding
Type
Value range
Units
Description
Usage
See also
PWAS
Direction
Binding
Type
Value range
Units
Description
Usage
See also
Rosemount Analytical Inc. A Division of Emerson Process Management
Analyzer: output; 1/0 module: input
PVACEMS
Floating point
0 - 1,000,000 typically, no hard limits though.
ppm
A copy of the primary variable (PVA), but with prior calibration factors applied.
During a calibration sequence, while PROCESS is set to something other than 0 by
the calibration module, PVACEMS reports the value of PVA using the values of the
calibration factors that were in use before the current calibration cycle. This allows an
1/0 module or DAS to record the drift experienced by the analyzer since the last
calibration. PVA is reported as well, but with the latest calibration factors applied. The
effect is that any span gas is reported through PVACEMS as if no zero calibration had
just been done, thus showing the total error in the span gas reading. As soon as
PROCESS goes back to 0, at the end of the calibration cycle, PVACEMS is no longer
updated, and its value becomes meaningless.
PVA
PROCESS
Analyzer: bidirectional; 1/0 module: input
PVU
Enumerated
ppm; ppb; %
None
Selects the units for all variables with values relating to the main reading for this
analyzer.
The NGA control module displays any variable with units defined as PVU, in the units
selected through the variable PVU. The value is still transmitted in ppm, but it is
interpreted as ppm, ppb or as percent as PVU is selected. It is important to note that
the value itself is not changed, it is merely displayed differently.
The 1/0 module copies this value so the control module can do the same thing with
1/0 menus.
PPU
PTU
Output
None
2-element floating point array
Both elements between 0 and 100.
None
NDIR only:
Oscillator tune at manufacturing time.
Percent modulation at manufacturing time.
Historical values of OSC_TUNE and PERCENT_MOD respectively. These show how
the instrument was working when it was tested during the manufacturing process.
These values are loaded automatically by the manufacturing data storage function.
OSC_TUNE
PERCENT_MOD
Reference Manual
748384-C
September 2003
Analyzer Variables 2-47