Campbell Scientific CR5000 Measurement and Control Module - Manual (Page 41)

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Section 2. Data Storage and Retrieval
The CR5000 can store individual measurements or it may use its extensive processing
capabilities to calculate averages, maxima, minima, histograms, FFTs, etc., on periodic or
conditional intervals. Data are stored in tables. For simplicity, the PC9000 program
generator allows a maximum of three data tables (in the native language up to 30 data
tables can be created). The number of tables and the values to output in each table are
selected when running the program generator (Overview) or when writing a datalogger
program directly (Sections 4 – 9).
2.1 Data Storage in CR5000
There are two areas for data storage on the CR5000:
Internal Static RAM
PCMCIA PC Card
Internal RAM is used as either the sole storage area for a data table or as a
buffer area when data are sent to PC card.
When the CR5000 gets a request for data that is stored on a PC card, the
CR5000 only looks for the data in the PC card when the oldest data are
requested or if the data are not available in internal RAM.
In the CRBASIC program, the DataTable instruction sets the size of the data
table or buffer area. A data table can be stored in a PC card by including the
CardOut instruction within the data table declaration. A maximum of 30
tables can be created by the program.
2.1.1 Internal Static RAM
Internal RAM is used as either the sole storage area for a data table or as a
buffer area when data are sent to a PC card. The only limit on the number of
tables is the available memory. Internal RAM is battery backed. Data remain in
memory when the CR5000 is powered down under program control. Data in
RAM are erased when a different program is loaded and run.
There are 2 Mbytes of SRAM. Some of this is used by the operating system
and for program storage. The rest is available for data storage. When a new
program is compiled, the CR5000 checks that there is adequate space in SRAM
for the data tables; a program that requests more space than is available will
not run.
2.1.2 PCMCIA PC Card
The CR5000 has a built in PC card slot for a Type I, Type II, or Type III
PCMCIA card. PCMCIA PC Cards allows expanding the CR5000’s storage
capacity. SRAM and ATA cards are supported. A program can send a
maximum of 30 data tables to PC cards.