Rockwell-automation Logix5000 Controllers Structured Text Programming Bedienungsanleitung PDF herunterladen (Seite 13)

Publication 1756-PM007D-EN-P - November 2012 13

Program Structured Text Chapter 1

Assign an ASCII Character to a String

Use the assignment operator to assign an ASCII character to an element of the

DATA member of a string tag. To assign a character, specify the value of the

character or specify the tag name, DATA member, and element of the

character.

To add or insert a string of characters to a string tag, use either of these ASCII

string instructions.

Expressions

An expression is a tag name, equation, or comparison. To write an expression,

use any of these elements.

• Tag name that stores the value (variable)

• Number that you enter directly into the expression (immediate value)

• Functions, such as: ABS, TRUNC

• Operators, such as: +, -, <, >, And, Or

As you write expressions, follow these general rules.

• Use any combination of upper-case and lower-case letter. For example,

these three variations of “AND” are acceptable: AND, And, and.

• For more complex requirements, use parentheses to group expressions

within expressions. This makes the whole expression easier to read and

ensures that the expression executes in the desired sequence.

This is OK This is not OK

string1.DATA[0]:= 65; string1.DATA[0] := A;

string1.DATA[0]:= string2.DATA[0]; string1 := string2;

To Use this instruction

Add characters to the end of a string CONCAT

insert characters into a string INSERT

IMPORTANT

You may add user comments inline. Therefore, local language

switching does not apply to your programming language.

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Rockwell-automation Logix5000 Controllers Structured Text Programming Bedienungsanleitung Seite 13