Campbell SC115, Руководство по эксплуатации продукта

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SC115 CS I/O 2G Flash Memory Drive with USB Interface
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COM ports on the computer (as memory devices, two SC115s may be
attached to a computer at the same time).
12. Troubleshooting Memory Drive
12.1 Preventing Data Corruption
To avoid corruption of SC115 memory, never remove the SC115 from the data
logger during data transfer. The flashing LED indicates when data is being
written to the SC115. Should the SC115 be removed while the LED is flashing,
the most likely result is that the current data file will be corrupted. In addition,
a FAT sector or the directory link sector may become corrupted. This condition
requires that the SC115 memory be reformatted, which will result in the loss of
all data.
When either the NumRecs/TimeIntoInterval or Interval parameters are set to a
non-zero positive value (resident modes), there is a risk that the data logger
will begin writing data to the SC115 at the exact moment it is being removed
from the data logger, resulting in data corruption. To prevent this, set these
parameters to values that allow the time between writing data to be easily
discerned (such as an interval of 10 seconds) by watching the LED. The user
then times the removal of the SC115 to occur when the data logger is not
writing data. See Section 10.5.2 , Resident Interval Mode Example
(p. 14)
.
Another method is to set the NumRecs parameter in TableFile() to match the
Size parameter in the associated DataTable() instruction. Depending on the
rate at which records are written, this can cause data to be written to the SC115
at long intervals, greatly reducing the chance of removing the SC115 from the
data logger while transferring data. See Section 10.5.3 , Resident Record
Number Mode Examples
(p. 14)
(second example).
If SC115 data becomes corrupted, first attempt to retrieve all files from the
SC115. Reformat the SC115 per Section 14.2 , Formatting Memory
(p. 20)
.
12.2 Skipped Scans
To avoid skipped scans, ensure that the scan interval in the data logger program
is long enough to include writing to the SC115. For example, if the program
has a single
TableFile()
instruction, add at least 100 ms to the scan rate to
accommodate each added TableFile() instruction.
Compile data logger programs in pipeline mode when possible. Data logger
programs compiled in sequential mode require a longer scan interval than
programs compiled in pipeline mode to avoid skipped scans. In pipeline mode,
the Scan() / NextScan instruction BufferOption parameter can be increased to
prevent skipped scans. In sequential mode, the TableFile() instruction must
finish before continuing to the next instruction, resulting in skipped scans
unless the scan interval is long enough to handle all communication,
measurement processing, and TableFile() tasks. Sequential mode ignores any
scan buffers that may be assigned. Programs may run as much as three times
faster in pipeline mode than in sequential mode.