OPENÕs System Variables
Background Information
Using the LI-6400
14-3
4
A short description.
This is what you see in the list generated by the ÒWhatÕs WhatÓ function key
in New Measurements mode.
5
A variable name
The variableÕs name is how you refer to it in a program. For example, if you
are writing an AutoProgram (Chapter 25) or defining a user variable (Chapter
15) and need to refer to the sample cell CO
2
concentration, the variable name
is
co2_2_um
.
Table 14-8 on page 14-19 lists the System Variables defined by OPEN, in-
cluding their labels, variable names, descriptions, and references to where
they are defined or discussed.
When Are They Computed?
In New Measurements mode, system and user variables are computed as fol-
lows:
1
Measured Quantities
The instrumentÕs A/D converter has a set of new readings available every
0.75 seconds. These readings are the raw signals from each sensor (including,
for example, the battery (V), the temperature sensors (mV), the CO
2
reference
IRGA (mV), etc.). Each time these new A/D readings are available, OPEN
computes the sensorÕs readings in meaningful units, and some ancillary val-
ues, such as relative humidity, which are based on multiple sensors.
Thus, system variables that are associated directly or indirectly with sensors
are computed and available with updated values every 0.75 seconds. These
variables are documented under the headings
2
User variables (photosynthesis rate, conductance, etc.)
Every 2.25 seconds, user variables are computed. These typically include
photosynthesis, conductance, etc. There are a couple of system variables that
are computed at this frequency as well, and these are described in
3
Status variables
ThereÕs a group of system variables that convey some system status informa-
tion. These are updated every 10 seconds, and are described in
Summary of Contents for LI-6400
Page 1: ...Using the LI 6400 Portable Photosynthesis System ...
Page 15: ...Part I The Basics ...
Page 16: ......
Page 174: ...Making Measurements Answers to Questions 4 56 Using the LI 6400 4 ...
Page 175: ...Part II Useful Details ...
Page 176: ......
Page 200: ...Standard Tools Power ON Hooks 5 24 Using the LI 6400 5 ...
Page 214: ...Real Time Data Real Time Graphics 6 14 Using the LI 6400 6 ...
Page 234: ...Environmental Control Light Control 7 20 Using the LI 6400 7 ...
Page 244: ...Light Sensor Considerations Gallium Arsenide Phosphide GaAsP Sensor 8 10 Using the LI 6400 8 ...
Page 288: ...Data Logging Making Your Own AutoPrograms 9 44 Using the LI 6400 9 ...
Page 289: ...Part III Working With Files ...
Page 290: ......
Page 312: ...The LPL File System Troubleshooting 10 22 Using the LI 6400 10 ...
Page 340: ...Downloading Files Using a Data Capture Program 11 28 Using the LI 6400 11 ...
Page 375: ...Part IV Configuration Issues ...
Page 376: ......
Page 420: ...Defining User Variables Old Style vs New Style 15 18 Using the LI 6400 15 ...
Page 454: ...Using an Energy Balance Further Reading 17 12 Using the LI 6400 17 ...
Page 455: ...Part V Maintenance Troubleshooting ...
Page 456: ......
Page 572: ...Troubleshooting Useful Information 20 46 Using the LI 6400 20 ...
Page 593: ...Part VI Programming ...
Page 594: ......
Page 622: ...Programming with LPL Compiler Directives 22 28 Using the LI 6400 22 ...
Page 846: ...Index I 16 Using the LI 6400 ...