Logix Designer, like most IEC 61131-3-compliant applications, takes any program you create in any IEC-compatible language, converts it into Instruction List (IL)—a low-level language that resembles assembly—and compiles it down to bytecode (the binary language used internally by the controller) in order for the controller to execute it.
The following diagram illustrates the ways that various languages are compiled down into the same bytecode language:
Ultimately, the controller is not aware of which language you created your program in (Ladder Logic, Function Block, or Sequential Function Chart); it always ends up as the same bytecode language that is executed on the controller. Within Logix Designer, you can create the exact same program using Ladder Logic that you would create using Function Block Diagrams (FBDs), and it would (in theory) translate down to the same Structured...