Call function blocks

The structured text programming language can call function blocks. Function block calls can be used in any expression, and contain properties explained in the following table.

Function block call properties

Properties of function block calls
Property
Description
Name
Name of the function block instance.
Meaning
Calls a function block from the standard library, or from a user-defined library, and accesses its return parameters.
Syntax
(* call of the function block *)
<blockname> ( <p1>, 2 : <p2> ... );
(* gets its return parameters *)
<result> := <blockname>. <ret_param1>;
...
<result> := <blockname>. <ret_paramN>;
Operands
Parameters are expressions that match the type of the parameters specified for that function block.
Return value
See syntax to get the return value.
Function block call example
Function block call example
When setting the value of the return parameter in the body of a function block, you can assign the return parameter using its name concatenated with the function block name:
FunctionBlockName.OutputParaName := <expression>;

Example

(* ST program calling a function block *)

(* declare the instance of the block in the variable editor: *)
(* trigb1 : block R_TRIG - rising edge detection *)

(* Function block activation from ST language *)
trigb1 (b1);
(* return parameters access *)
If (trigb1.Q) Then nb_edge := nb_edge + 1; End_if;
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