HOW TO IMPORT AND EXPORT .DXF DRAWING FILES

DXF stands for Data eXchange File. It is a relatively universal method of transferring 2D and 3D vector information between various graphic and CADD programs. The limitations of the DXF file have more to do with the DXF specifications and less to do with DataCAD itself. DXF files are meant to be generic and therefore do not interpret or transfer many "higher order" functions in DataCAD.

Much of the information here came from Bruce Kaplan, the author of the DXF PREP (CheapTricks Ware No. B26) macro. Items noted with an asterisk (*) are "corrected" by the DXF PREP macro. You can do all of them manually, but the macro is a cheap and fast method to automate it all.
 

A. THE BI-DIRECTIONAL LIMITATIONS OF DXF FILES ARE:

1. Only 4 fonts are directly compatible: SIMPLEX, COMPLEX, ROMANS, ROMANC. (*)
2. Only 4 line types will transfer: SOLID, DASHED, DOTTED, and DOT-DASH.
3. The DXF protocol only supports 3D entities (polygons) with a maximum of 4 vertices and no thickness (3-D).

1. Layer names must be all CAPITALS and contain only DOS characters. (*)
2. DataCAD's associative hatches do not transfer. The bounding polygon will, but no hatch will be displayed within it. The solution is to explode the associative hatch into non-associative hatching prior to creating the DXF file (see the explanation of Changing Associative Hatching to Non-Associative Hatching, below).
3. Nested symbols (symbols made up of other symbols) will not transfer. (*)
4. Single point polylines will cause an abort (usually caused by a user error). (*)
5. DataCAD's DXF process will "tesselate" (bust up) the higher order 3D entities (i.e. slabs) into individual polygon surfaces (no more than 4 vertices). The coincident edges of the coplanar polygons will be invisible to give the appearance of it being being one whole 3D entity.
6. DataCAD's 2-1/2 D entities must be "squashed" to 2D only. Do this by changing the Z-base and Z-height of all entities to zero. (*)
7. Unused symbol definitions should be purged. Do this by going to Directry/SymFiles/PurgeSym. (*)
8. For each drawing you wish to export via DXF, make sure the limitations of DXF protocol have been observed, are accounted for, or have been corrected (this is what the DXF PREP macro is good for).
9. Do the following to set up for DXF'ing. In DataCAD's CONFIG program select one of the DXF compatible fonts as your default character set. Then create a clean default drawing that you will use only for DXF.
10. Run the LYRUTIL macro and save out all the layers you want to keep (use Save All or Save On).
11. Open up your DXF default drawing and create a new file, then use LYRUTIL to read in the layers you previously saved out.
12. Once in the new drawing make sure that the layers you want to DXF are displayed (if the layer is OFF it won't be written into the DXF file), then go to File I/O\DXF\WriteDXF to create the DXF file.

C. From AUTOCAD-to-DATACAD:

1. If the AutoCAD drawing uses offset polylines to draw walls (or any other parallel lines), these polylines should be exploded to regular entities.
2. Do the following to set up for DXF'ing. In DataCAD's CONFIG program select one of the DXF compatible fonts as your default character set. Then create a clean default drawing that you will use only for DXF.
3. For each drawing you wish to import via DXF: Go to File I/O\DXF\ReadDXF and choose the DXF file to import. If you didn't know the base units the drawing was created in you should check the actual size of a distance of known dimension (e.g. a door opening). If it is the wrong size you can either use Enlarge to adjust the drawing by a factor or you can reset the DXF import Scale and go through the ReadDXF process again.

CHANGE ASSOCIATIVE HATCHING TO NON-ASSOCIATIVE:

There are two ways to explode Associative Hatching to Non-Associative. The first method (2D) is alright if you don't care to maintain the original hatch ORIGIN. For an amorphous hatch such as concrete, cement, etc., you probably don't care about where the origin is. But if you used Associative Hatching to make an acoustic tile ceiling, or a tile floor, where the ORIGIN of the pattern is critical, then you must use the second method (3D).

Method No. 1 (2D) - Does not retain Origins:

1. Go to Hatch and make sure Associat is turned OFF.
2. Pick your hatch(es) by Area/Entity, etc.
3. Click on DelAssoc and the associative hatching will be changed to non-associative. The hatch lines will now be individual entities.

1. Go to the DataCAD 3D Menu.
2. Pick Explode/ToLines.
3. Pick your hatches by Area/Entity, etc. It's easiest to do them all at once by Area.
4. The hatch lines will now be exploded to individual 3D entities, while retaining the individual origins of each hatch.
5. Use the 3D LINE CONVERT (Available from the DataCAD WEB site - 3DLNCVT.ZIP) macro to convert the 3D hatch lines to 2D lines.