Campbell Scientific CR9000X Measurement and Control System - Manual (Page 141)

Section 4. CRBasic – Native Language Programming
TABLE 4.2.4-1. Data Types
Code Data Format Where Used Word
Size Range Resolution
FP2 CSI Floating
Point
Output Data Storage 2 bytes ±7999 13 bits
(about 4 digits)
IEEE4 or
FLOAT IEEE 4 Byte
Floating Point Output Data Storage,
Variable Declaration 4 bytes ±1.4 x 10 -45 to
±3.4 x 10 38
24 bits
(about 7 digits)
LONG 4 Byte Signed
Integer Output Data Storage,
Variable Declaration 4 bytes -2,147,483,648
to
+2,147,483,647 1 bit (1)
UINT2 2 Byte Unsigned
Integer Output Data Storage 2 bytes 0 to 65535 1 bit (1)
BOOLEAN 4 byte Signed
Integer
Output Data Storage,
Variable Declaration 4 bytes 0, -1 True or False
(-1 or 0)
BOOL8 1 byte Boolean Output Data Storage 1 byte 0, -1 True or False
(-1 or 0)
NSEC Time Stamp Output Data Storage 8 byte seconds since
1990 1 nanoseconds
STRING ASCII String Output Data Storage,
Variable Declaration
Set by
program
4.2.4.5 Data Type Operational Detail
BOOLEAN “AS BOOLEAN” specifies the variable as a 4 byte Boolean. Boolean variables
are typically used for flags and to represent conditions or hardware that have
only 2 states (e.g., On/Off, Ports). A Boolean variable uses the same 32 bit
long integer format as a LONG but can set to only one of two values: True,
which is represented as –1, and false, which is represented with 0. To save
memory space, consider using BOOL8 format instead.software to display it as
an ON/OFF, TRUE/FALSE , RED/BLUE, etc.
Public Switches(8) AS Boolean, FLAGS(16) AS Boolean
BOOL8 Used for data storage only. A one byte variable that hold 8 bits (0 or 1) of
information. BOOL8 uses less space than 32-bit BOOLEAN data type, since
32 bits of information are stored in four 8-bit Boolean bytes. Repetitions in
output processing data table instructions must be integrally divisible by two,
since an odd number of bytes cannot be stored in a data table. When
converting from a LONG or a FLOAT to a BOOL8, only the least significant 8
bits are used, i.e., only the modulo 256 is used. When LoggerNet retrieves a
BOOL8 data type, it splits it apart into 8 fields of true or false when storing or
displaying. BOOL8 conserves CR9000X memory which results in less band
width being used when data are collected via telecommunications.
EXAMPLE 4.2.4-3 programs the CR9000X to monitor the state of 32 ‘alarms’
as a tutorial exercise. The alarms are toggled by manually entering zero or
non-zero (e.g., 0 or 1) in each public variable representing an alarm. Samples
of the four FlagsBool variables are stored in data table “Bool8Data” as four 1-
byte values. When programming, remember that aliasing can be employed to
make the program and data more understandable for a particular application.
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