The file extension PLN identifies the file format of the CAD software ArchiCAD. Designed by the Hungarian company Graphisoft, the program is aimed primarily at architects and is used for the design of building structures, interior, exterior and landscape.
A special feature of ArchiCADs is the use of a so-called virtual building, in which the procedure for the construction of a real building is simulated.
PLN is a proprietary format and can only be read by ArchiCAD. Unfortunately, some PLN files from older archicad versions (8 and below) can not be opened with the current version. However, Graphisoft offers free converters that convert old PLN files into the new format.
Most often resolving problems with opening PLN files is very simple. Just install an appropriate program that supports such files. All of the listed programs support PLN files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of PLN files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate PLN files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the ArchiCAD applications is not on the list, select "Browse" option in order to manually locate the directory where ArchiCAD has been installed.
Sometimes problems with opening PLN files may not lie with the application itself, but can arise due to other causes, such as: