If you want to use your LD network as a PLC for calling up other POUs , then you must merge a POU with an EN input. Such a POU is connected in parallel to the coils. Beyond such a POU you can develop the network further, as in the Function Block Diagram. You can find the commands for insertion at an EN POU under the menu item 'Insert' 'Insert at Blocks'.

An operator, a function block, a program or a function with EN input performs the same way as the corresponding POU in the Function Block Diagram, except that its execution is controlled on the EN input. This input is annexed at the connecting line between coils and contacts. If this connection carries the information "On", then the POU will be evaluated.

If a POU has been created once already with EN input, then this POU can be used to create a network. This means that data from usual operators, functions, and function blocks can flow in an EN POU and an EN POU can carry data to such usual POUs.

If, therefore, you want to program a network in the LD editor, as in FBD, you only need first to insert an EN operator in a new network. Subsequently, from this POU, you can continue to construct from your network, as in the FBD editor. A network thus formed will perform like the corresponding network in FBD.