Emerson iPro SERIES Instrukcja Użytkownika Pobierz pdf (Strona 56)

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1592025400 – Vers. 1.0 - 56 -

8. PROGRAMMING LANGUAGES

8.1 ST language – General concepts

The environment of ST language is composed by:

• STATEMENT

:= assignment

( ) priority

IF, THEN, ELSE, ELSIF, END_IF; binary selection

CASE, OF, ELSE, END_CASE; selection

WHILE, REPEAT, END_WHILE, END_REPEAT; iterations

FOR, TO, BY, DO, END_FOR; indexed iterations

RETURN; program termination

EXIT; iteration statement termination

BOOLEAN OPERATOR (decreasing priority)

NOT boolean negation

AND boolean AND

OR boolean OR

XOR boolean exclusive OR

=, <>, >=, <=, <, > comparisons

+, -, *, / arithmetic operators

Beware of:

WHILE and REPEAT have to be used with special care.

arithmetic operator can be used for integer DINT or REAL.

• TIME

+ addition

- subtraction

Beware of subtraction: negative timer as result means nothing.

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Emerson iPro SERIES Instrukcja Użytkownika Strona 56