A UDF (User-Defined Function block) provides you a convenient way to deal with circuit logic that is composed of a group of function blocks and used in several places of a circuit program or among multiple circuit programs. A UDF helps you avoid copying and pasting a common set of blocks to multiple places and results in more readable program logic with fewer connection lines. With a UDF, you can do the modifications of all occurrences of the circuit logic at just one place.
To create and use a UDF, follow these steps:
Edit mode: create and edit a UDF
You can create a new UDF via menus or toolbars, and edit this UDF.
You can use a group of selected blocks in an existing circuit program as the start contents of the new UDF.
You can save the UDF to a UDF library path where you can import the UDF later.
You can create your own UDF library or copy a UDF library from a third party.
Use mode: use the UDF in an FBD or in another UDF (nested UDF)
If you have imported the UDF, it is available in the block tree like general function blocks. You can use it in the same way as a general function block.