5.4.1 CPU drive
The serial flash memory CPU drive contains data logger programs and other files. This memory is
managed in File Control.
NOTE:
When writing to files under program control, take care to write infrequently to prevent
premature failure of serial flash memory. Internal chip manufacturers specify the flash
technology used in Campbell Scientific CPU: drives at about 100,000 write/erase cycles. While
Campbell Scientific's in-house testing has found the manufacturers' specifications to be very
conservative, it is prudent to note the risk associated with repeated file writes via program
control.
Also, see System specifications (p. 210) for information on data logger memory.
5.5 MicroSD (CRD:drive)
The data logger has a microSD card slot for removable, supplemental memory. The card can be
configured as an extension of the data logger final-data memory or as a repository of discrete
data files. In data file mode, sub folders are not supported.
The CRD: drive uses microSD cards exclusively. Its primary purpose is the storage of data files in a
compact binary format. Campbell Scientific recommends and supports only the use of microSD
cards obtained from Campbell Scientific. These cards are industrial-grade and have passed
Campbell Scientific hardware testing. Use of consumer grade cards substantially increases the risk
of data loss. Following are listed advantages Campbell Scientific cards have over less expensive
commercial-grade cards:
l Less susceptible to failure and data loss.
l Match the data logger operating temperature range.
l Provide faster read/write times.
l Include vibration and shock resistance.
l Have longer life spans (more read/write cycles).
A "card controller error"indicates that the data logger has failed to communicate with the card. It
is an error caused by the micro-controller built into the microSD card. If the error repeats itself, try
an industrial-grade card.
A maximum of 30 data tables can be created on a microSD card. When a data table is sent to a
microSD 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
5. Data memory 61
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