Open the pdf in Reader and select the graphics "snapshot tool". Draw a rectangle around the graphic you want to import and it will be copied to the clipboard. Open IrfanView or another image editor and paste it in there and save that as a tif, png, bmp, whatever. You can then insert that into DataCAD and use the Enlarge command to calculate the enlargement so you can scale it.
Dick
DataCAD user since version 2