Rockwell Automation 57C610 Enhanced Basic Language, AutoMax - Manual (Page 33)

5Ć1
5.0 EXPRESSIONS
An expression is a symbol or a group of symbols that BASIC can
evaluate. These symbols can be numbers, strings, constants,
variables, functions, array references, or any combination of these.
The following are the different types of operations which can be
performed:
1. Arithmetic expressions/operators
2. String expressions/operators
3. Boolean expressions/operators
4. Relational expressions/operators
5.1 Arithmetic Expressions
BASIC allows you to perform addition, subtraction, multiplication,
division, and exponentiation with the following operators:
** Exponentiation
* Multiplication
/ Division
+ Addition, Unary+
- Subtraction, Unary-
The unary plus and minus are different from the other operators
because they operate on only one operand, not two. The standard
operators (binary operators) require two operands.
The following expressions use binary operators:
MOTOR_SPEED% + JOG_SPEED%
GAIN% Ć GAIN_CHANGE%
GAIN% * GAIN_FACTOR%
The following expressions use unary operators:
GAIN - SPEED (Legal but results in a positive value)
-MOTOR_SPEED%
-(GAIN%+GAIN FACTOR%)
+MOTOR_SPEED% (This form is not typically used because
it is assumed that the absence of an operator in front of a
variable means plus or positive)
Unary minus makes a positive expression negative. Unary plus does
not make a negative expression positive. A unary minus applied to a
variable already having a negative value will, of course, make the
variable (or expression) positive.
The symbols for unary plus and minus (+ and -)are the same as
the binary plus and minus, but the operation is different. For
example, A% - B% means subtract B% from A%, whereas -(A%)
means negative the value of A%.
Performing an operation on two arithmetic expressions of the same
data type yields a result of that same data type. For example, A% +
B% yields an integer, and K$ + M$ yields a string.
When a real value (constant or variable) is used in an expression
with any other numeric data type (single integer, double integer, or
real) the result is always real. When a boolean value is used in an