Calling Function Blocks

The Structured Text (ST) programming language enables calling function blocks. Function block calls can be used in any expression.
Function Block calls
Name
Name of the function block instance
Meaning
Calls a ST, LD, or FBD function block or a "C" function block and gets its return parameters
Syntax
(* call of the function block *)

<blockname> ( <p1>, 
PLC-2
 ... );

(* gets its return parameters *)

<result> := <blockname>. <ret_param1>;

...

<result> := <blockname>. <ret_paramN>;
Operands
Parameters are expressions which match the type of the parameters specified for that function block
Return value
See Syntax to get the return parameters.
When setting the value of the return parameter in the body of a function block, 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 dictionary: *)

(* 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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