A function block is called in ST by writing the name of the instance of the function block and then assigning the values of the parameters in parentheses. In the following example a timer is called with assignments for the parameters IN and PT. Then the result variable Q is assigned to the variable A.
The result variable is addressed with the name of the function block, a following point, and the name of the variable:
CMD_TMR(IN := %IX5, PT := 300); A:=CMD_TMR.Q