Section 7. Installation
198
Constants, in memory, are four-byte signed integers or floating point numbers of
up to about 500 characters in length (length limited to the maximum
command
line
(p. 576)
length).
CRBasic syntax does not have a provision for declaring a data type for a constant,
so the compiler infers data type based on the format of the constant value
expression, which is usually a single scalar. There are three possible outcomes:
•
string — the constant expression produces a string or the value is
enclosed in quotes
•
integer — the constant expression does not produce a floating point
v
alue or the constant does not have a decimal point. Range =
–2,147,483,648 to 2,147,483,647
•
floating point. Range ≈
–1E38 to 1E38
If the constant is not written as a decimal, the compiler treats the value as an
integer. Integer and floating point values are represented by 32 bits. A
floating-point value achieves its extended range by using a base-two exponential
format. The range of integers that a floating-point value can reliably store is
limited by the size of the mantissa, which is
±
16,777,216. If the attempt is made
to express a floating-point constant outside of this range, precision may be lost.
Constants in a constant table can also be changed using the
SetSetting()
instruction and the constant table using the CR1000KD.
Note
Using all uppercase for constant names may make them easier to
recognize.
Using the Const Declaration
'This program example demonstrates the use of the Const declaration.
'Declare variables
Public
PTempC
Public PTempF
'Declare constants
Const
CtoF_Mult = 1.8
Const
CtoF_Offset = 32
BeginProg
Scan
(1,Sec,0,0)
PanelTemp
(PTempC,250)
PTempF = PTempC * Cto CtoF_Offset
NextScan
EndProg
7.6.3.8.1 Predefined Constants
Many words are reserved for use by CRBasic. These words cannot be used as
variable or table names in a program. Predefined constants include instruction
names and valid alphanumeric names for instruction parameters. On account the
Summary of Contents for CR6 Series
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Page 76: ...Section 5 Overview 76 FIGURE 20 Half Bridge Wiring Example Wind Vane Potentiometer ...
Page 80: ...Section 5 Overview 80 FIGURE 23 Pulse Input Wiring Example Anemometer ...
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Page 454: ...Section 8 Operation 454 FIGURE 104 Narrow Sweep High Noise ...
Page 459: ...Section 8 Operation 459 FIGURE 106 Vibrating Wire Sensor Calibration Report ...
Page 535: ...Section 8 Operation 535 8 11 2 Data Display FIGURE 121 CR1000KD Displaying Data ...
Page 537: ...Section 8 Operation 537 FIGURE 123 CR1000KD Real Time Custom ...
Page 538: ...Section 8 Operation 538 8 11 2 3 Final Storage Data FIGURE 124 CR1000KD Final Storage Data ...
Page 539: ...Section 8 Operation 539 8 11 3 Run Stop Program FIGURE 125 CR1000KD Run Stop Program ...
Page 541: ...Section 8 Operation 541 FIGURE 127 CR1000KD File Edit ...
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Page 610: ...Section 11 Glossary 610 FIGURE 137 Relationships of Accuracy Precision and Resolution ...
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