Lenze DDS v2.3 Uživatelský manuál stáhnout pdf (Strana 135)

100

101

Drive PLC Developer Studio

Editors

7-13

l DDS EN 2.3

Application example

An operating hour meter that is to continue counting after a mains failure.

• All other variables will be re-initialized either with the standard initial values (0 or FALSE) or

with the defined initial values.

Example:

VAR RETAIN

rem1:INT; (* 1. retentive variable *)

END_VAR

7.2.7 Constants, typed literals

Between the keywords VAR CONSTANT and END_VAR, all constants are declared.

• Constants can be declared locally or globally.

Syntax:

VAR CONSTANT

<Identifier>:<Type> := <Initialization>;

END_VAR

Example:

VAR CONSTANT

con1:INT:=12; (* 1. constant *)

END_VAR

For a list of permitted constants refer chapter on Operands.

(^ 13-1)

7.2.8 Retentive constants

Between the keywords VAR CONSTANT RETAIN and END_VAR, all retentive constants are

declared.

• Retentive constants can be declared locally or globally.

Syntax:

VAR CONSTANT RETAIN

<Identifier>:<Type> := <Initialization>;

END_VAR

Example:

VAR CONSTANT RETAIN

Acceleration: DINT:=10000; (* acceleration time *)

END_VAR

7.2.9 Keywords

• Alleditorsrequirekeywordstobewrittenincapitals.

• Keywords must not be used as variable names.

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