Access to Variables in Arrays, Structures, and Blocks

Access to array elements

Syntax:

<name of array variable> [ <comma-separated list of dimension indexes> ]

<name of array variable>

Name of the array variable

Example: aiCounter

For more information, see: Designating Identifiers

<comma-separated list of dimension indexes>

One index per dimension, so that one element of the array is identified

Example: 2

The index is valid from the index minimum to the index maximum. Example: 0..9

Example 195. Examples

One-dimensional array with 10 components

//Declaration
VAR
    aiCounter : ARRAY[0..9] OF INT;
    iLocalVariable : INT;
END_VAR

// Implementation
iLocalVariable := aiCounter[2];

Two-dimensional array with 2 times 2 components

//Declaration
VAR
    aiCardGame : ARRAY[1..2, 3..4] OF INT;
    iLocal_1 : INT;
END_VAR

//Implementation
iLocal_1 := aiCardGame[1, 3];

For more information, see: ARRAY OF

Access to structure components

Syntax:

<name of structure variable> . <name of component>

<name of structure variable>

Example: sPolygon

For more information, see: Designating Identifiers

<name of component>

Example: aiStart

Example 196. Example

//Declaration type
TYPE S_POLYGONLINE :
STRUCT
    aiStart : ARRAY[1..2] OF INT := [-99, -99];
    aiPoint1 : ARRAY[1..2] OF INT;
    aiPoint2 : ARRAY[1..2] OF INT;
    aiPoint3 : ARRAY[1..2] OF INT;
    aiPoint4 : ARRAY[1..2] OF INT;
    aiEnd : ARRAY[1..2] OF INT := [99, 99];
END_STRUCT
END_TYPE

//Declaration structure variable
VAR
    sPolygon : S_POLYGONLINE;
    iPoint : INT;
END_VAR

//Implementation
iPoint := sPolygon.aiPoint1[1];

For more information, see: STRUCT

Access to variables in POUs

Syntax:

<POU name> . <variable name>

<POU name>

Name of a function block instance (FUNCTION_BLOCK) or a program (PROGRAM)

Example: fbController

For more information, see: Designating Identifiers

<variable name>

Variable of the POU

Example: xStart

Example 197. Example

FUNCTION_BLOCK FB_Controller
VAR_INPUT
    xStart : BOOL;
END_VAR
VAR_OUTPUT
END_VAR
VAR
    ControlDriveA : S_CONTROL;
END_VAR
IF xStart = TRUE THEN
    //Symbolic bit access
    ControlDriveA.bitEnableOperation := TRUE;
END_IF

PROGRAM PLC_PRG
    fbController : FB_Controller;
END_VAR
fbController();
fbController.xStart := TRUE;