LI-COR LI-6400, Руководство пользователя

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Data Logging
9-2 Using the LI-6400
9
The LI-6400 provides a great deal of flexibility in choosing what is logged,
and how it is logged. This chapter explains what goes on, and how you can
modify logging to suit your purposes.
Basic Concepts
The LI-6400, in its default configuration, is an open system. As such, it shows
a continuous stream of measurements and calculations. You can monitor light
levels and photosynthetic rates, for example, while changing those light lev-
els. Over the course of, say, 5 minutes, the LI-6400 will have made hundreds
of measurements. The question is, which of these will you want to retain for
future use?
Person A might only want two sets of data: one when conditions were stable
at light level X, and another 5 minutes later at light level Y. Person B, how-
ever, might be studying the dynamics of the change from X to Y, and want to
record data as frequently as possible over that 5 minutes.
Where does it go?
When the LI-6400 records data, it generally does so in its file system, which
is described in Chapter 10. It can also record data in memory, or send it out
of the RS-232 port in real time. Files can be named, allowing you to go back
and retrieve your prized data that you stored under some meaningful name
like Ò
junk Ó, or “test 1 Ó, or the ever-popular Ò A-Ci curve right before lunch Ó.
What gets stored?
Data files contain ÒsnapshotsÓ. That is, whenever you think it appropriate,
you can store in your file a set of data for that instant in time. A file can con-
tain 1 or 100 or more such observations. Or no observations. The observations
can be irregularly spaced, recorded manually and whimsically, or evenly
spaced, recorded automatically based on time. They can even be recorded au-
tomatically when the program determines that stability has been achieved.