Frank, I'm not sure about the VCN510 because it has the Nexus640 control, but I know the Variaxis 730 with the Fusion640 will have the HD Operation Function. It's a pretty handy feature, and more user friendly than a typical drip-feed setup. The major drawback is you can't view the code as it's running. You can only monitor the commands that are coming up on the next line.
You will need the IC memory card or an ethernet connection in order to load a large program into the right folder on the hard drive. You can drag-and-drop from the floppy drive, but you can only fit 1.44MB on a floppy.
There are also specific criteria for making a file ready to run via the HD Operation Function, so make sure you read up on it in the manual. It's just minor stuff like(If I remember correctly):
-Dragging-dropping the program to the correct folder on the hard drive.
-No "%" sign at the start or end of the program.
-File name must be XXXX.eia (Replace XXXX with your desired program number.)
-No sub programs can be called from an HD Operation program.
Whenever I run from the HD, I create a normal EIA program to use as a main, and then call the HD programs as subs.
If you need to edit the HD program, just double-click it in Windows Explorer, and it will open in either Notepad or Wordpad.