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MELSEC-Q
2 THE BASICS OF AD51H-BASIC
• Division when overflow occurs or when the divisor is 0.
If a divisor becomes 0 in a division while executing an expression, a “Division by
zero” error will occur. Also, if 0 is lifted to a negative power, a “Division by zero” error
will occur.
When an overflow occurs, an “Overflow” error will be generated.
• Mixing with other types of operators
An expression can contain logical operators, other than arithmetic operators. When
an expression contains a relational operator, the arithmetic operation is performed by
returning the value –1 if the result of the logical operation is True, and value 0 if the
result of the logical operation is False.
Example
(A=B) (A>C)
(A AND MASK)/2
2.10.2 Relational operators
Relational operators are used to compare two values. The results of comparisons are
expressed as either “True” (-1) or “False” (0). Results such as these are used to
determine the program flow.
Operator
Meaning
Example
=
Equal to
X=Y
<>, ><
Not equal to
X<>Y, X><Y
<
Less than
X<Y
>
Greater than
X>Y
<=, =<
Less than or equal to
X<=Y, X=<Y
>=, =>
Greater than or equal to
X>=Y, X=>Y
The "equal to" symbol (=) is also used to assign a value
to a variable.
When a relational operator and an arithmetic operator both exist in the same equation,
the arithmetic operator will always take priority. The result is then used for the relational
operation.
Example
X+Y<(T-1)/Z
• • • • •
The result is True if the value X + Y is less than
T-1
Z
SIN(X)<0
• • • • •
The result is True if the value SIN(X) is less than 0.
