Rockwell-automation 1771-DB BASIC MODULE Manual de usuario descargar pdf (Pagina 119)

100

101

Chapter

Expressions, Variables and Operators

9 -9

Relational expressions involve the operators =, < >, >, >=, <, and <=.

In the BASIC module, you typically use relational operations to test a

condition.

The BASIC module relational operators return a result of 65535 (0FFFFH)

if the relational expression is true, and a result of 0 if the relation

expression is false. The result returns to the argument stack. Because of

this, it is possible to display the result of a relational expression.

>PRINT

1=0

PRINT 1>0

65535

PRINT A<>A

PRINT A=A

65535

You can chain relational expressions with the logical operators .AND.,

.OR., and .XOR. (page 9 -8). This makes it possible to test a complex

condition with one statement.

>10

IF (A>E).AND.(A>C).OR.(A>D)THEN...

Additionally, you can use the NOT operator (page 9 -11).

>10

IF NOT(A>E).AND.(A>C)THEN...

Important: When using logical operators to link relational expressions,

you must be sure operations are performed in the proper sequence.

When in doubt, use parentheses.

Relational Operators

1 2 ... 114 115 116 117 118 119 120 121 122 123 124 ... 393 394

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