ArchiCAD supports DWG CAD format from AutoCAD so you can simply export the .pln projects and save them as .dwg drawings. It doesn't seem any other program supports projects from ArchiCAD, so the original program seems to be your only choice.
Convert ArchiCAD solo project to AutoCAD drawing.
We found one software available in the database for this conversion.
Microsoft Windows software - convert pln to dwg on Windows
One of the architecture CAD software programs
Convert from pln file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.