AutoCAD Electrical supplies hundreds of PLC modules if you install every manufacturer (maybe thousands - I've never actually counted). But, if you look at the drawings in the library folder you won't see many PLC modules. That is because AutoCAD Electrical builds most of the PLC modules on-the-fly. The end result is a block with attributes, but it is actually built from a small set of building blocks. This method has some advantages over supplying all those PLC module blocks (besides taking up less disk space).
- Module adapts to the rung spacing
- I/O style can be selected at insertion time
- Breaks and spacers can be added as needed
Of course AutoCAD Electrical can't supply every possible PLC module. So, that means there are times when you need to add a module. Or you might want to change how an existing module is built. But, with this parametric method it is a little more complicated than just opening a library symbol and making the changes. All the information to build a module is stored in the PLC database file, ace_plc.mdb. But, you don't have to edit that file directly. The PLC Database Editor should be used to make all modifications.
Watch this video for an overview of the Parametric PLC feature and using the PLC Database Editor.