A9Convert is a command line program to convert DWG/DXF to different versions of DWG/DXF. It supports up to Autocad 2010.

Operating Systems: Windows XP/Vista/7

License: Freeware 

Current Version: 10.1

Download Link: http://www.a9tech.com/assets/downloads/a9convert.zip

Major Features:

•Standalone converter. No AutoCAD installation is required.
•Command line application. Can be used to script batch converting multiple files at one time.
•Convert DWG to DXF.
•Convert DXF to DWG.
•Perform version conversion among DWG files.
•Perform version conversion among DXF files.
•Read/Write AutoCAD R2.5, R2.6, R9, R10, R13, R14, 2000, 2002, 2004, 2005, 2007 and 2010.
Usage:

usage: a9convert source_file target_file target_format target_version
                   Target format options: DWG|DXF
                   Target version options: R2.5|R2.6|R9|R10|R12|R13|R14|R2000|R2004|R2007|R2010
                 –help Print the help.
                 –version Print the version.

Examples:
a9convert wall.dwg c:tempwall2.dwg DWG R2000
a9convert d:cadfileswall.dxf c:tempwall2.dxf DXF R2010