Convert2DXF command line app is available to download and test.Convert2DXF Command Line App
Included in the zip file is a readme.txt file that has several examples on how to call it.
The order of the parameters does not matter and the simplest way to call it is with one parameter, the PDF filename and path. If any paths have spaces in them you will need to wrap them in double quotes ("C:\my folder\mypdf.pdf", "C:\my folder\mydxf.dxf"). Specifying only the PDF file name and path will create the DXF file in the same directory as the PDF.
Parameters are separated by a space.
Other parameters include ...
The path and filename where to save the DXF file (file extension must be .dxf).
IN to specify Inches (defaults to Millimeters)
BCLMODE to convert paths to LwPolylines, arcs, and circles where it can.
If you have any issues please let me know.