
Section 9. Program Control Instructions
Parameter
& Data Type
Enter
Option
Constant
The Option parameter determines how data will be buffered during the
Scan…NextScan process. The options are:
Option Result
0, 1, or 2 The datalogger uses two buffers when processing
measurements. When a measurement begins on a scan,
the values of the previous scan are loaded into a buffer.
This allows processing to finish on the previous scan
during measurement of the current scan.
>3 The datalogger uses three or more buffers when
processing measurements, based on the number of scans
defined by this Constant.
Larger buffers can be used for a Scan that has occasional large processing
requirements such as FFTs or Histograms, and/or when processing may be
interrupted by communications. If a value of 1000 is inserted into the
BufferSize argument of a scan having 10 thermocouple measurements,
40,000 bytes of SRAM will be allocated for the buffer [(4 bytes) /
(measurement) x (10 measurements)/(buffered scan) x 1000 buffered
scans)]. The buffer size plus the size of any Output Tables stored in SRAM
should not exceed 4 megabytes (serial # ≥3605) or 2 megabytes (serial #
<3605).
If the processing ever lags behind by more than the buffer allocated, the
datalogger will discard the buffered values and synchronize back up to the
current measurement
The SlowSequence instruction does not allow for this buffering scheme
even though Scan is used to signify the start of a scan in a slow sequence.
In SlowSequence, the measurements are stored in a single buffer.
Processing of this buffer is completed before the NextScan measurements
are made.
Count
Integer
The number of times to execute the Scan/NextScan loop. Enter 0 for infinite
looping.
SelectCase … EndSelect
Executes one of several statement blocks depending on the value of an
expression.
Syntax
SelectCase testexpression
[Case expressionlist1
[statementblock-1] ]
[Case expressionlist2
[statementblock-2] ]
[CaseElse
[statementblock-n] ]
EndSelect
The Select Case syntax has these parts:
9-13
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