Graph with Many Points

[Murad Karrar]

Hello everybody, this is my first time using this newsgroup, I've been
playing around with labview for the past week. I've found it great for
data acquisition. I'm trying to build an application that requires the
logging of an EEG signal. I first was thinking of saving the data in a
database but then I thought that it would require a large number of
fields and would take a large memory space. Is there any other way of
saving the data for easy retrievel in the future.

Thanx in adavance.

[MaxMar]

You may be interested in using Labview's datalog file type.
There are examples that ship with LV in the \examples\file
folder. There is a file there named "datalog.llb" that has
several examples of reading/writing datalog files.

The datalog format is binary and allows the user to read the
data directly into a Labview data type without having to parse,
as you would with an ASCII file. This makes writing small
utilities for viewing or processing the data in Labview much
easier. In most of my large apps that gather lots of data
across many tests runs, I use a two-pronged approach. The
engineers prefer to have the data written to Excel because they
know the environment well and are able to construct report
templates in advance; plus they like all of the data to be in
one place. From a programmer's safety point of view, I don't
particularly like the idea of having all the data in one file.
So I write apps that log the data to a Labview datalog file (and
also an identical backup file, if the user so chooses) where it
can be retrieved by small, specialized VI's. At the same time,
I use ActiveX to write the data to Excel files that have been
designed as report templates, so when the data collection is
done, the report is done. Most of my apps have a companion data
retrieval utility that recalls the log file contents for viewing
and exporting to other file formats, such as Excel, Text, or
MSAccess, just in case someone asks for the data in some form
other than the Excel report. I manager the data types across the
separate Test and data processing VI's by using Typedefs.

I work in an R&D environment where the scientists manage their
own reports and do their own data analysis, so the above
arrangement works pretty well. The production side of our
company is a much different story, though. They use a central
database because the data is more extensively analyzed by many
different people and departments.


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