Campbell Scientific CR1000 Measurement and Control System - Manual (Page 333)

Section 8. Operation
333
CRD:
Principal use is to expand Final Storage (p.
454), but it is also used to store .JPG, cr1, and
.DAT files.
1
The CPU: drive uses a FAT16 file system, so it is limited to 128 file. If the file names are longer
than 8.3 characters (e.g. 12345678.123), you can store less.
2
The USR: drive uses a FAT32 file system, so there is no practical limit to the number of files that
can be stored on it. While a FAT file system is subject to fragmentation, performance degradation
is not likely to be noticed since the drive is small and solid state RAM (very fast access).
8.3.1.1.1 Data Table SRAM
Primary storage for measurement data are those areas in SRAM allocated to data
tables as detailed in table CR1000 SRAM Memory
(p. 331).
Measurement data can
be also be stored as discrete files on USR: or USB: by using TableFile()
instruction.
The CR1000 can be programmed to store each measurement or, more commonly,
to store processed values such as averages, maxima, minima, histograms, FFTs,
etc. Data are stored periodically or conditionally in data tables in SRAM as
directed by the CRBasic program (see Structure
(p. 112)
). The DataTable()
instruction allows the user to set the size of a data table. Discrete data files are
normally created only on a PC when data are retrieved using datalogger support
software
(p. 77).
Data are usually erased from this area when a program is sent to the CR1000.
However, when using support software File Control menu Send
(p. 454)
command
or CRBasic Editor Compile, Save and Send
(p. 451)
command, options are
available to preserve data when downloading programs.
8.3.1.1.2 CPU: Drive
CPU: is the default drive on which programs and calibration files are stored. Do
not store data on CPU: or premature failure of CPU: memory may result.
8.3.1.1.3 USR: Drive
SRAM can be partitioned to create a FAT32 USR: drive, analogous to partitioning
a second drive on a PC hard disk. Certain types of files are stored to USR: to
reserve limited CPU: memory for datalogger programs and calibration files.
Partitioning also helps prevent interference from data table SRAM. USR: is
configured using DevConfig settings or SetStatus() instruction in a CRBasic
program. Partition USR: drive to at least 11264 bytes in 512-byte increments. If
the value entered is not a multiple of 512 bytes, the size is rounded up. Maximum
size of USR: is the total RAM size less 400 kB; i.e., for a CR1000 with 4-MB
memory, the maximum size of USR: is about 3.6 MB.
USR: is not affected by program recompilation or formatting of other drives. It
will only be reset if the USR: drive is formatted, a new operating system is
loaded, or the size of USR: is changed. USR: size is changed manually using the
external keyboard / display or by loading a program with a different USR: size
entered in a SetStatus() instruction.
Measurement data can be stored on USR: as discrete files by using the
TableFile() instruction. Table TableFile()-Instruction Data-File Formats
(p. 336)
describes available data-file formats.