[1] Ladder logic [5] (LAD) is a graphic programming language. The syntax of the instructions is akin to a circuit diagram. Via LAD, we can follow a signal flow between power rails via inputs, outputs, and instructions. It has all elements to create a full user program, the full range of basic instructions and wide range of addresses available.
[5] Functions and function blocks allow to structure an LAD program clearly. The LAD Programming Package is an integral part of the STEP 7 Standard Software, meaning this installation of a STEP 7 software, all editor functions, compiler functions, and test/debug functions for LAD
are available to us.
integral:
[5] Via LAD, we can create our own user program via the Incremental Editor. The input of the local block data structure is made easier with the help of table editors.
[5] 3 programming languages are in the standard software, STL, FBD, and LAD. We can switch from an language to another almost freely and choose the suitable language for a block we program. If we write programs in LAD or FBD, we always switch over to the STL representation. If we convert LAD programs into FBD programs and vice versa, program elements that can't be represented in the destination language are shown in STL
[1] Wikipedia
[2]
[3]
[4] Ladder Logic (LAD) for S7-300 and S7-400 Programming - Cache Industry Siemens (PDF)
[4.1] saved file (Discord)
[5] Ladder Logic (LAD) for S7-300 and S7-400 Programming - Brescianet (PDF), this file appears to be different version of the Cache Industry Siemens', althought similar
[5.1] saved file (Discord)