Campbell Scientific SDM-CD8S 8 Channel Solid State DC Control Module - Manual (Page 22)

SDM-CD8S 8 Channel Solid State DC Control Module
The sequence in the example, with the six sample intakes and two calibration
gases, is to measure 3 sample intakes, measure the zero and span, measure the
other 3 intakes, and again measure the zero and span. There are 10 sites in the
sequence. (The SiteSequence array is dimensioned to 10 elements.) The
sequence is 1, 2, 3, 7, 8, 4, 5, 6, 7, 8. Thirty seconds is spent on each site the
sequence. Thus it takes 5 minutes to run through the sequence of 10 sites (10
sites x 30 seconds/site). This sequence is repeated again and again.
OmitCounts: When the manifold is switched to a new site, it is necessary to
purge the line before the analyzer measurement represents the new site. The
program includes a counter that is incremented by one each scan. The omit
counts is number of measurements to exclude from an average for the site after
switching to the site.
The program records averages for each time the manifold is set to a site. The
average does not include values measured while the count is less that the omit
count. The count is reset to 0 when the program switches to a new site. In this
program there is a constant omitcounts that is used for all sites. If it was
necessary to set the Omit Counts independently for each site, OmitCounts
could be a variable array instead of a constant.
8.3.2 Data Tables
There are two data tables, RawData and SiteAvg. RawData holds samples of
every measurement. SiteAvg holds averages that are calculated for a site when
the manifold is switched to the next site.
8.3.3 Initialization Section (between BeginProg and Scan)
Manifold/SDMCD8S Settings: This section defines the bit pattern for each
valve setting.
Site Sequence: Edit the SiteSequence array assignment for the sequence
desired. For example, the 10 element SiteSequence array described in the
Terminology section above can be loaded with the code:
'Load SiteSequence
SiteSequence(1) = 1
SiteSequence(2) = 2
SiteSequence(3) = 3
SiteSequence(4) = 7
SiteSequence(5) = 8
SiteSequence(6) = 4
SiteSequence(7) = 5
SiteSequence(8) = 6
SiteSequence(9) = 7
SiteSequence(10) = 8
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