of the period in 10 ms increments up to 24 hours. As shown in CRBasic example
BeginProg / Scan() / NextScan / EndProg Syntax
(p. 155), the CRBasic program
may be relatively short.
CRBasic Example 14. BeginProg / Scan() / NextScan / EndProg Syntax
'This program example demonstrates the use of BeginProg/EndProg and Scan()/NextScan syntax.
Public PanelTemp_
DataTable(PanelTempData,True,-1)
DataInterval(0,1,Min,10)
Sample(1,PanelTemp_,FP2)
EndTable
BeginProg ' <<<<<<<BeginProg
Scan(1,Sec,3,0) ' <<<<<<< Scan
PanelTemp(PanelTemp_,250)
CallTable PanelTempData
NextScan ' <<<<<<< NextScan
Scan() determines how frequently instructions in the program are executed, as
shown in the following CRBasic code snip:
'Scan(Interval, Units, BufferSize, Count)
Scan(1,Sec,3,0)
'CRBasic instructions go here
ExitScan
Scan() has four parameters:
• Interval — the interval between scans. Interval is 10 ms ≤ Interval ≤ 1 day.
• Units — the time unit for the interval.
• BufferSize — the size (number of scans) of a buffer in RAM that holds the
raw results of measurements. When running in pipeline mode, using a buffer
allows the processing in the scan to lag behind measurements at times
without affecting measurement timing. Use of the CRBasic Editor default
size is normal. Refer to section SkippedScan
(p. 487) for troubleshooting tips.
• Count — number of scans to make before proceeding to the instruction
following NextScan. A count of 0 means to continue looping forever (or until
ExitScan). In the example in CRBasic example Scan Syntax
, the scan is one
second, three scans are buffered, and measurements and data storage continue
indefinitely.
7.8.4.12.2 SlowSequence / EndSequence
Slow sequences include automatic and user entered sequences. Background
calibration is an automatic slow sequence. A
User-entered slow sequences are declared with the SlowSequence instruction and
run outside the main-program scan. Slow sequences typically run at a slower rate
than the main scan. Up to four slow-sequence scans can be defined in a program.
Instructions in a slow-sequence scan are executed when the main scan is not
active. When running in pipeline mode, slow-sequence measurements are spliced
in after measurements in the main program, as time allows. Because of this
splicing, measurements in a slow sequence may span across multiple-scan
155
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