Declaration of input variables in ST

Syntax

VAR_INPUT (* optional_begin *) RETAIN NON_RETAIN (* optional_end *)
  name_1, name_2, ..., name_n  : data-type := initial-value;
  name_3, name_4, ..., name_n  : STRING[length] := 'initial-value';
  name_5, name_6, ..., name_n  : ARRAY [x..y] OF data-type := [initial-value_1, initial-value_2, .., initial-value_n];
  name_7, name_8, ..., name_n  : ARRAY [x1..y1, x2..y2, x3..y3] OF data-type;  (* Here, initial values are possible as well. *)  
  name_9, name_10, ..., name_n : REF_TO type := REF(name_A);
 
(* Additional pieces of data, such as partial addresses, are also possible for the variables. *)
(* Note: If a function block type is used as type for the variable, it is actually a function block instance. *)
END_VAR

Meaning

Declaration of one or more →input variables, name_1, name_2 etc. must be →IEC-identifiers.
The declaration of more sections of this kind is allowed. The declaration is possible within declaration of a →program, of a →function block, of a →function or of a →method.

Providing the optional keyword RETAIN or NON_RETAIN makes all elements of this section →retentive or non-retentive. RETAIN or NON_RETAIN is possible within the declaration of a program and the declaration of a function block . If variables are declared based on a structured data type within the section with RETAIN or NON_RETAIN, its structure elements (incl. nestings) are treated as retentive or non-retentive alike.

A →data type is possible as type for a variable.

See "Supported data types" to learn which data types are supported for the declaration of variables. Use the optional →initial value [:= initial-value] to assign a value to the variable (see "Initialization of variables in ST" for details).
Moreover, it is possible to declare:

STRING variables; details: see "Declaration of STRING variables (incl. access)"
array variables – this is similar to the declaration of an array data type

reference variables; details: see "Declaration of reference variables (incl. assignments to them)"

The declaration of input EN is not necessary. See "Execution control: EN, ENO" for information on input EN.

Good to know

Moreover, logi.CAD 3 allows you to specify additional data for the declaration . See " Defining description, comment, JSON string or type for variables or data types " for details.

Moreover, logi.CAD 3 allows you to define a not yet fully specified location for the declaration. See "Declaration of a language element with partial address in ST" for details.

Within a section VAR_INPUT...END_VAR, it is also possible to declare function block instances and to declare variables based on an interface.

Example

VAR_INPUT
  IN1, IN2 : INT;
  T1 : TIME; 
  IN3: ARRAY [1..2] of BOOL;
  IN4 : STRING[10]; 
  myRefIN: REF_TO INT;
END_VAR