Campbell Scientific CR9000X Measurement and Control System - Manual (Page 147)

Section 4. CRBasic – Native Language Programming
4.2.5 Constants
A constant can be declared at the beginning of a program to assign an
alphanumeric name to be used in place of a value so the program can refer to
the name rather than the value itself. Using a constant in place of a value can
make the program easier to read and modify, and more secure against
unintended changes. Constants can be changed while the program is running if
they are declared using the ConstTable/EndConstTable instruction. See
Example 4.2.5-1.
Programming Tip: Using all uppercase for constant names may make them
easier to recognize.
EXAMPLE 4.01. CRBASIC Code: Using the Const Declaration
Public MTempC, PTempF
ConstTable
Const CTOF_MULT = 1.8
Const CTOF_OFFSET = 32
EndConstTable
BeginProg
Scan (1,Sec,0,0)
ModuleTemp (MTempC,1,4,250)
MTempF = MTempC * CTOF_MULTult + CTOF_OFFSET
NextScan
EndProg
4.2.6 Flags
Flags are a useful program control tool. While any variable of any data type
can be used as a flag, using Boolean variables, especially variables named
“Flag”, works best. If the value of the variable is -1 the flag is high. If the value
of the variable is 0 the flag is low (Section 4.6). CSI's logger support software
looks for the variable array with the name Flag when the option to display flag
status is used in one of the real time screens. EXAMPLE 4.0-1 shows an
example using flags to change the word in string variables.
EXAMPLE 4.0-1. CRBASIC Code: Flag Declaration and Use
Public Flag(8) As Boolean
Public FlagReport(2) As String
BeginProg
Scan (1,Sec,0,0)
If Flag(1) = True Then
FlagReport(1) = "High"
Else
FlagReport(1) = "Low"
EndIf
If Flag(2) = True Then
FlagReport(2) = "High"
Else
FlagReport(2) = "Low"
EndIf
NextScan
EndProg
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