Campbell CR850, Руководство оператора

Страница: 130 / 566

Section 7. Installation
130
If a program is planned to experience multiple lapses, and if telecommunications
bandwidth is not a consideration, the
Lapses parameter should be set to 0 to
ensure the CR800 allocates adequate memory for each data table.
Table 14. DataInterval() Lapse Parameter Options
DataInterval()
Lapse
Argument
Effect
X > 0
If table record number is fixed, X data frames (1 kB per data
frame) are added to data table if memory is available. If record
number is auto-allocated, no memory is added to table.
X = 0
Time stamp and record number are always stored with each
record.
X < 0
When lapse occurs, no new data frame is created. Record time
stamps calculated at data extraction may be in error.
Scan Time and System Time
In some applications, system time (see System Time
(p. 445)
) is desired, rather than
scan time (see Scan Time
(p. 442)
). To get the system time, the CallTable()
instruction must be run outside the Scan() loop. See section Time Stamps
(p. 269).
OpenInterval() Instruction
By default, the CR800 uses closed intervals. Data output to a data table based on
DataInterval() includes measurements from only the current interval.
Intermediate memory that contains measurements is cleared the next time the data
table is called regardless of whether a record was written to the data table.
Typically, time series data (averages, totals, maxima, etc.) that are output to a data
table based on an interval only include measurements from the current interval.
After each output interval, the memory that contains the measurements for the
time series data are cleared. If an output interval is missed (because all criteria are
not met for output to occur), the memory is cleared the next time the data table is
called. If the
OpenInterval instruction is contained in the DataTable()
declaration, the memory is not cleared. This results in all measurements being
included in the time series data since the last time data were stored (even though
the data may span multiple output intervals).
Note Array-based dataloggers, such as CR10X and CR23X, use open intervals
exclusively.
Data Output-Processing Instructions
Final data storage processing instructions (aka "output processing" instructions)
determine what data are stored in a data table. When a data table is called in the
CRBasic program, final data storage processing instructions process variables
holding current inputs or calculations. If trigger conditions are true, for example if
the output interval has expired, processed values are stored, or output, into the
data table. In CRBasic example
Definition and Use of a Data Table
(p. 127),
three
averages are stored.