Campbell Scientific CR3000 Micrologger - Manual (Page 344)

Section 8. Operation
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will be represented by four field names: “values(1,1)”, “values(1,2)”,
“values(2,1)”, and “values(2,2)”. Scalar (non‐array) variables will not
have subscripts.
Line 3 – Data Units
Includes the units associated with each field in the record. If no units
are programmed in the CR3000 CRBasic program, an empty string is
entered for that field.
Line 4 – Data-Processing Descriptors
Entries describe what type of processing was performed in the CR3000
to produce corresponding data, e.g., Smp indicates samples, Min
indicates minima. If there is no recognized processing for a field, it is
assigned an empty string. There will be one descriptor for each field
name given on Header Line 2.
Record Element 1 – Timestamp
Data without timestamps are usually meaningless. Nevertheless, the
TableFile() instruction optionally includes timestamps in some formats.
Record Element 2 – Record Number
Record numbers are optionally provided in some formats as a means to
ensure data integrity and provide an up‐count data field for graphing
operations. The maximum record number is &hffffffff (a 32‐bit
number), then the record number sequence restarts at zero. The
CR3000 reports back to the datalogger support software 31 bits, or a
maximum of &h7fffffff, then it restarts at 0. If the record number
increments once a second, restart at zero will occur about once every
68 years.
8.3.2 Memory Conservation
One or more of the following memory-saving techniques can be used on the rare
occasions when a program reaches memory limits:
• Declare variables as DIM instead of Public. DIM variables do not require
buffer memory for data retrieval.
• Reduce arrays to the minimum size needed. Arrays save memory over the
use of scalars as there is less "meta-data" required per value. However, as a
rough approximation, 192000 (4-kB memory) or 87000 (2-kB memory)
variables will fill available memory.
• Use variable arrays with aliases instead of individual variables with unique
names. Aliases consume less memory than unique variable names.
• Confine string concatenation to DIM variables.
• Dimension string variables only to the size required.