Campbell Scientific Open Path Eddy Covariance (OPEC) - Manual (Page 25)

OPEC Open-Path Eddy-Covariance System
4.1.3 Remote Data Retrieval via a PC/CF Card
To transfer data manually from the PC/CF card to the PC, remove the card
from the datalogger following the proper card removal procedure (see the
appropriate datalogger manual for details). Insert a fresh card into the
datalogger or copy the data from the card to a working directory on the
computer. Transferring data using the PC/CF card is relatively fast. A 1024
Mbyte file (about 28 days of 10 Hz time series data) will take about 15 minutes
to copy from the card to a PC hard drive.
While the PC/CF card is not in the datalogger, the datalogger will continue to
collect and save the data in the CPU. When the card is returned to the
datalogger, the data will be transferred automatically from the CPU to the card.
When a card is inserted into a CRBasic datalogger, the
datalogger will transfer all the data that was collected since the
card was removed. It is good practice to avoid keyboard and RS-
232 activity during this time. After the datalogger is finished
transferring the data to the card, the LED will blink at a steady
frequency. NOTE
The amount of CPU storage, for time series data, varies from data logger to
datalogger. The Status Table reports the time it takes to fill the CPU and CRD
DataTables in the “DataFillDays” fields. The third DataFillDays field is the
fill time for the CPU time series data table.
Never remove a PC/CF card from the datalogger or turn off
power to the datalogger without first shutting down the
card. With a CR3000 or CR1000, press the “Removal
Button” on the CFM100 Compact Flash/NL115
Ethernet/Compact Flash module. With a CR5000 select
the PCCard|Remove Card menu. CAUTION
Data can be retrieved from a datalogger using one or two cards. If a single card
is used, and data on the card is not deleted after copying it to the PC, the data
from the CPU will be appended to the file on the card when it is returned to the
datalogger. Using a single card in this fashion allows the site attendant to
create files of uniform size.
The disadvantage of this approach, if the time between site visits is
significantly less than the DataTable file time, is that there will be redundant
data copied, along with the new data. This approach is not practical if the PC
can not be brought to the site or the time it takes to copy the data from the card
to the PC is greater than the time it takes to fill the CPU time series DataTable.
As an alternative, two cards can be used. The site attendant will remove the
card in the datalogger and replace it with a fresh one. This method is fast and
does not require a PC at the site. The disadvantage of this approach is that it
will create non-uniform file sizes around the time that the cards are exchanged.
If the time series data is processed by EdiRe, nonuniform file sizes are not an
issue. The files could be spliced together using the Append option in
CardConvert.
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