Symbol:

Implement more program code in an action. You can implement this program code as the base implementation in another language. The base implementation is a function block or a program where you inserted the action.

An action does not have its own declaration and it works with the data from the base implementation. This means that the action uses the input and output variables and the local variables from its base implementation.

Add an “Action” to a function block or program by clicking “Project  Add Object  Action”.

Input support when generating inheriting POUs

When you doing object-oriented programming and using the inheritance (keyword ‎EXTENDS‎) of POUs, you can get support as follows:

When you insert an action, a property, a method, or a transition below a POU derived from a base POU, the “Add …” dialog opens. Then the input field for the name extends to a list box. The list box contains a valid selection from the actions, properties, methods, or transitions available in the base POU. Now you can, for example, easily accept a method of the base POU and then adapt it to the derived function of the POU.

Methods and properties with the access modifier ‎PRIVATE‎ are not listed here because they are also not inherited. Methods and properties with the access modifier ‎PUBLIC‎ automatically get a blank access modifier field when accepting into the derived POU, which means the same thing functionally.

Example

Calling an action

Syntax:

‎<program>.<action>‎ or ‎<FB instance>.<action>‎

To call an action from only within the base implementation, you only have to provide the action name.

Examples

Calling a “Reset” action from another POU The call is not executed from the base implementation.

Declaration:

PROGRAM PLC_PRG
VAR
    Inst : Counter;
END_VAR

Calling a “Reset” action from an IL POU

CAL Inst.Reset(In := FALSE) 
LD Inst.Out
ST ERG

Calling a “Reset” action from an ST POU

Inst.Reset(In := FALSE);
Erg := Inst.out;

Calling a “Reset” action from an FBD POU