System Software for S7-300 and S7-400 System and Standard Functions Reference Manual - The S7 CPUs have integrated system functions and organization blocks included with their operating system, which you can use when programming.If you’re more comfortable with Ladder Logic or Function Block Diagram then start there but sooner or later you’ll have to become familiar with Statement List. You only require one language type for programming an S7-300/S7-400, but you can mix the languages within a project, if required.
Once you install the Step 7 software there will be a directory under the SIMATIC folder called Documentation that includes the most important manuals. Where to Start? Manuals, manuals, everywhere! The best thing for this is the sales catalog (ST 70 – 2005). Getting used to part numbers and product groupings can go a long way with your comfort level. The first thing I like to do with a new product is get an overview of everything. There are differences between the regular version of Step 7 and Step 7 Lite but for learning purposes you can go along way with the free Lite version.
There’s a lot of different stuff there thrown together and found in different spots with very long URL addresses to add to the confusion. From a new users perspective I’ve only heard disparaging comments about finding the right information on the Siemens’ website.
This is a listing of tutorials and manuals found on the Siemens automation website that will get you started on the SIMATIC Step 7 software for S7-300 and S7-400 systems.