Reference Manual
748384-C
September 2003
Rosemount Analytical Inc. A Division of Emerson Process Management I/O Modules Variables
3-13
NGA2000 Reference
CRANGEO
CRANGEO, CRANGEOA, CRANGEOB, CRANGEOC, CRANGEOD
Direction Output
Binding
CRANGE
Type Enumerated
Value range
1; 2; 3; 4.
Units None
Description
Determines current analyzer range.
SCAL only uses CRANGEOA etc. to bind to each of its analyzer modules.
Usage
Bound to CRANGE in the analyzer, this is used to control the analyzer range, as
opposed to CRANGEI which tells the 1/0 module what the analyzer thinks its range
is.
See also
CRANGEI
CRANGE (in Section 2)
DWELL
Direction output
Binding
None
Type Integer
Value range
1-300
Units Seconds
Description
ACAL and SCAL only; dwell times for the calibration cycles.
The local zero gas dwell time.
The local span gas dwell time.
The local sample purge dwell time.
The remote zero gas dwell time.
The remote span gas dwell time.
The remote sample purge dwell time.
Usage
The zero gas dwell time is the time the calibration module allows zero gas to flow
before telling the analyzer(s) to perform a zero. The analyzer will then wait until it
detects a stable signal, or its time out is up, before doing a zero. The span gas
dwell time is the equivalent waiting time before the calibration module tells the
analyzer to span, and the sample dwell time is the time after spanning is complete
before the sample can be expected to have purged the span gas and the PVA
value of the analyzer has come to a realistic reading. In general the zero time must
be longer than the span time, normally by about a factor of 2, and the sample time
may be the same as or somewhat less than the span time. These times are
dependent partially on the sample system delays, and partially on the inherent
analyzer response times. The dwell times should be a minimum of ten times the
nominal analyzer response time; the latter is defined as the time to a 90% reading,
and in calibration it is essential that the analyzer comes to a 99.9% reading for 0. 1
% span or zero accuracy.
See also
CALSTAT