Campbell Scientific CR1000KD CR800 and CR850 Measurement and Control Systems - Page 113

Section 7. Installation 7.7.3.2 Structure Table CRBasic Program Structure (p. 113) delineates CRBasic program structure. CRBasic example Program Structure (p. 114) demonstrates the proper structure of a CRBasic program. Table 9. CRBasic Program Structure Declarations Define CR800 memory usage. Declare constants, variables, aliases, units, and data tables. Declare constants List fixed constants. Declare Public variables List / dimension variables viewable during program execution. Dimension variables List / dimension variables not viewable during program execution. Define Aliases Assign aliases to variables. Define Units Assign engineering units to variable (optional). Units are strictly for documentation. The CR800 makes no use of Units nor checks Unit accuracy. Define data tables. Define stored data tables. Process / store trigger Set triggers when data should be stored. Triggers may be a fixed interval, a condition, or both. Table size Set the size of a data table. Other on-line storage devices Send data to a Campbell Scientific mass-storage media (USB: drive) if available. Processing of data List data to be stored in the data table, e.g. samples, averages, maxima, minima, etc. Processes or calculations repeated during program execution can be packaged in a subroutine and called when needed rather than repeating the code each time. Begin program Begin program defines the beginning of statements defining CR800 actions. Set scan interval The scan sets the interval for a series of measurements. Measurements Enter measurements to make. Processing Enter any additional processing. Call data table(s) Declared data tables must be called to process and store data. Initiate controls Check measurements and initiate controls if necessary. NextScan Loop back to set scan and wait for the next scan. End program End program defines the ending of statements defining CR800 actions. 113