Lenze PLC Designer PLC Designer (R3-1) Instrukcja Użytkownika Pobierz pdf (Strona 77)

L-force | PLC Designer

Concepts and Base Components

 DMS 4.1 EN 03/2011 TD29 75

If the instance is inserted via input assistant (<F2>) with option With arguments in the

implementation window of a ST or IL POU, it will be displayed automatically according

to the syntax showed in the following example with all of its parameters. But you not

necessarily must assign these parameters. For the above mentioned example the call

would be displayed as follows:

Example, insert via input assistant with arguments:

CMD_TMR(in:=, pt:=, q=>)

-> fill in, e.g.:

CMD_TMR(in:=bvar, pt:=t#200ms, q=>bres);

Extension of a function block

Supporting object orientated programming a function block can be derived from

another function block. This means a function block can extend another, thus

automatically getting the properties of the basing function block in addition to its

own.

The extension is done by using the keyword EXTENDS in the declaration of a function

block. You can choose the "extends" option already during adding a function block to

the project via the Add Object dialog.

The syntax:

FUNCTION_BLOCK <function block name> EXTENDS <function block name>

This is followed by the declaration of the variables.

Example:

Definition of function block fbA:

FUNCTION_BLOCK fbA

VAR_INPUT

x:int;

....

Definition of function block fbB:

FUNCTION_BLOCK fbB EXTENDS fbA

VAR_INPUT

ivar:int;

....

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Lenze PLC Designer PLC Designer (R3-1) Instrukcja Użytkownika Strona 77