5 crd: drive – Campbell Scientific CR3000 Micrologger User Manual
Page 340
Section 8. Operation
340
8.3.1.1.5 CRD: Drive
CRD: drive uses CompactFlash
®
(CF) memory cards exclusively. Its primary
purpose is the storage of binary data files. See File-System Errors
(p. 352)
for
explanation of error codes associated with CRD: use.
Caution When installing or removing card-storage modules, first turn off
CR3000 power. Removing a card from the module while the CF card is active
can cause data corruption and may damage the card. Always press the removal
button to disable the card and wait for the green LED before removing the card or
switching off power prior to removal of the card.
To prevent losing data, collect data from the CF card before sending a program to
the datalogger. When a program is sent to the datalogger all data on the CF card
may be erased.
Campbell Scientific CF card modules connect to the CR3000 peripheral port.
Each has a slot for Type I or Type II CF cards. A maximum of 30 data tables can
be created on a CF card. Refer to Writing High-Frequency Data to CF Cards
(p.
for information on programming the CR3000 to use CF cards. Refer to the
appendix Card-Storage Modules
for information on available CF-card modules.
Note CardConvert software, included with mid- and top-level datalogger support
software
converts binary card data to the standard Campbell Scientific
data format.
When a data table is sent to a CF card, a data table of the same name in SRAM is
used as a buffer for transferring data to the card. When the card is present, the
Status table will show the size of the table on the card. If the card is removed, the
size of the table in SRAM is shown.
When a new program is compiled that sends data to the CF card, the CR3000
checks if a card is present and if the card has adequate space for the data tables. If
no card is present, or if space is inadequate, the CR3000 will warn that the card is
not being used. However, the user program runs anyway and data are stored to
SRAM. When a card is inserted later, data accumulated in the SRAM table are
copied to the CF card.
Formatting CF Cards
The CR3000 accepts cards formatted as FAT or FAT32; however, FAT32 is
recommended. Otherwise, some functionality, such as the ability to manage large
numbers of files (>254) is lost. Older CR3000 operating systems formatted cards
as FAT or FAT32. Newer operating systems always format cards as FAT32.
To save time, use a PC to format CF cards. After formatting the card, write any
file to the card, then delete the file. This action sets up the card for faster initial
use.
FAT32 uses an “info sector” to store the free cluster information. This info sector
prevents the need to repeatedly traverse the FAT for the bytes free information.
After a card is formatted by a PC, the info sector is not automatically updated.
Therefore, when the datalogger boots up, it must determine the bytes available on
the card prior to loading the Status table. Traversing the entire FAT of a 16 GB
card can take up to 30 minutes or more. However, subsequent compile times are
much shorter because the info sector is used to update the bytes free information.
To avoid long compile times on a freshly formatted card, format the card on a PC,