Campbell Scientific PC400 Datalogger Support Software - Manual (Page 183)

Section 9. Datalogger Program Creation with CRBasic Editor
Define Subroutines If there is a process or series of calculations
that needs to be repeated several times in the
program, it can be packaged in a subroutine
and called when needed rather than repeating
all the code each time.
Program The program section defines the action of
datalogging.
Set scan interval The scan sets the interval for a series of
measurements.
Measurements Enter the measurements to make.
Processing Enter any additional processing with the
measurements.
Call Data Table(s) The Data Table must be called to process output
data.
Initiate controls Check measurements and Initiate controls if
necessary.
NextScan Loop back (and wait if necessary) for the next
scan.
End Program
9.4.2 Program Declarations
Variables must be declared before they can be used in the program. Variables
declared as Public can be viewed in display software. Variables declared using
Dim cannot be viewed. Variables assigned to a fixed value are used as
constants.
For example, in a CRBasic program there may be multiple temperature (or
other) sensors that are wired to sequential channels. Rather than insert multiple
instructions and several variables, a variable array with one name and many
elements may be used. A thermocouple temperature might be called TCTemp.
With an array of 20 elements the names of the individual temperatures are
TCTemp(1), TCTemp(2), TCTemp(3), ... TCTemp(20). The array notation
allows compact code to perform operations on all the variables. For example,
to convert ten temperatures in a variable array from C to F:
For I=1 to 10
TCTemp(I)=TCTemp(I)*1.8+32
Next I
Aliases can also be created that will allow an element of an array or another
data result to be referred to by a different name. To continue the example
above, TCTemp(3) could be renamed using the following syntax:
Alias TCTemp(3) = AirTemp
In the display software, the more descriptive alias, AirTemp, would be used for
the cell name.
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