“Execution order”

In the CFC editor, you position the elements and therefore also the networks freely. Two modes are available to prevent the execution order in the CFC POU from being undefined.

“Auto Data Flow Mode”

In this mode, the execution order is determined automatically by data flow, or in case of ambiguity, by network topology. The POUs and the outputs are numbered internally. The networks are executed from top to bottom and left to right.

Advantage: The automatically defined execution order is optimized by time and by cycle. You do not need any information about the internally managed execution order during the development process.

The following commands are provided afterwards in the “CFC  Execution Order” menu:

The elements in the CFC editor are displayed without markers and without numbering. It is not possible to change the execution order manually. For networks with feedback, you can also set a starting point.

“Explicit Execution Order Mode”

In this mode, you can define the execution order explicitly. To do this, the elements are displayed in the CFC editor with markers and numbering, and menu commands are provided for defining the order.

The following commands are provided in the “CFC  Execution Order” menu:

Note: Up to CODESYS V3.5 SP1, this was the usual behavior of CFC POUs. Pay attention that it is your responsibility to adapt the execution order and assess the consequences and impacts. This is another reason why the execution order is always displayed.

“Apply to All CFCs”

Changes the mode for all other CFC objects in the project to the mode selected in the list