Sequoia LISST-25X, Руководство по эксплуатации

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LISST - 25 User’s Guide
5
Step 7: Set the
instruments internal
clock The internal instrument clock can be set in two ways. The first method is
by clicking on the button. This will set the instrument clock to the
PC clock time. The second method is by using the ST command. Enter
ST in the command box and press enter. Messages will prompt you for
the date and time. You can also enter the date and time after the ST
command to bypass the prompts (e.g.,
ST 01/05/2003 21:05:03). [Note
that the year is four digits and the hour is in 24-hour format.]
Step 8: Acquire
clean water
background
measurements Before accurate measurements can be made, the background light
scattering of the optical surfaces must be measured. This background is
subtracted from the measured scattering in the field so that only the
scattering from the particles in the water are used for processing of the
data. The instrument will need to be submerged in clean filtered water.
Check to make sure the windows and water are free of bubbles. The “
ZS ”
command will acquire and store the necessary background measurements
for later use. If there is a problem such as dirty windows or optical
misalignment messages will be displayed to the screen.
Step 9: Add Sample
and Display results We can now add material to the water to take actual measurements of
suspended solids. Add the material and make sure it is well mixed. At the
prompt enter “
GX ”. The date and time, total volume, mean size, and
optical transmission will be displayed to the screen. The LISST-25X only
measures volume, not mass. The instrument is shipped with a Calibration
Constant that has been computed using a density of 1. The Calibration
constant can be adjusted by using the command “
SC ”. For example, you
can convert the standard units of micro-liters per liter to milligrams/liter
by dividing the standard calibration constant by the density.
Step 10: Load a
Batch File
The LISST-25X is designed to be a self-contained instrument. One of the
features that support this functionality is the ability to load and execute a
list of commands. A batch file of up to 25 commands can be loaded into
memory. Commands for creating loops, both fixed length and continuous,
are also provided.
Start by loading the first line of the batch file with the command for
displaying the status of the instrument (“
DS ”). Enter “ LB 01 DS ”. This
will load batch line 1 with the DS command. The commands can be
entered in either capital or lowercase letters. The batch line value
following the “
LB ” command MUST be two characters. Let’s add a few
more lines to setup this example. Type in the following lines at the L25>>
prompt.
LB 02 GR 5
LB 03 WT 20
LB 04 GT 2
Line 2 will get 5 samples at the sample rate selected by the SR command,