Here are some useful add-in related Visual C++ Samples / VC++ Examples Program links I've started collecting. This section is still very much under construction, and more links will be appearing in the future. ... PLC Programming , Read data from PLC , Write Data to PLC , PLC Communication. ... C++ Article STL Iterator and the VC++ MFC Iterator .... STL, LAD or FBD. Correspondingly, S7-SCL blocks can be called in STL, LAD, and FBD programs. When used in actual application cases, S7-SCL blocks can be recompiled into the STEP7 programming language STL. Recompiling into the S7-SCL is not possible. During compilation, those blocks are generated from the previously edited program that are runnable.