Campbell Scientific RTDAQ Software - Manual (Page 359)

Appendix A. Campbell Scientific File Formats
Header line two consists of a set of comma-delimited strings identifying the
names of the fields in the table of the datalogger program.
Header line three describes the units associated with each field in the record.
Units are optional and are specified in the datalogger program, if included. If
no units are provided in the program, then an empty string placeholder is left in
this line for that specific field.
Header line four describes the processing performed in the datalogger to
produce the value for each field in the record; for example, sample, average,
min, max, etc. If there is no known processing for a field, that field will be
assigned an empty processing string. There will be one value on this line for
each field name given on header line two.
Header line five describes the data type for each field and supports the
following values: IEEE4, IEEE8, FP2, ULONG, LONG, SecNano, BOOL, and
ASCII(len).
Each data record following the header is a sequence of binary values. The
length of each value is determined by the data type assigned to it in header line
five and the length of the entire record is the sum of the individual data value
lengths. There are no characters that separate records so the application that
reads the TOB1 file must understand the file header so that the record length
can be calculated.
The timestamp and record number for each record are an optional output in a
TOB1 file. If these elements are present, a “SECONDS”,
“NANOSECONDS”, and “RECORD” column will be generated as names in
the field list of header line two.
A.2 Datalogger Data Formats
A.2.1 TOB2 or TOB3
TOB2 and TOB3 files are created when data is stored on external PC cards
with dataloggers such as the CR9000X, CR5000, CR3000, and CR1000. Once
data has been collected from the card using RTDAQ or LoggerNet, it is stored
in another format, such as TOB1 or TOA5. Only uncollected data files on
cards (or copied from cards) are in the TOB2 or TOB3 format. The TOB2 file
format has been replaced in newer datalogger operating systems by the TOB3
file format. TOB3 format is similar to TOB2 in most respects but differs from
TOB2 in the following ways:
• Frame headers in TOB3 are 12 bytes long rather than 8 bytes long. The
additional 4 bytes contain an unsigned integer with the least significant
byte written first to identify the record number for the first record in the
frame.
• In the TOB3 format, the offset field in the major frame footer no longer
represents the number of frames back to the last minor frame. This
information is used in TOB2 to help accelerate searching for data but is
not considered to be necessary in TOB3 because of the presence of the
record number in the frame header.
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