Well, I think for now I'll keep the spindle under dl06 control while I get the rest of the machine on line. I'll engineer some kind of alarm that will trip an estop is the spindle doest respond to Mach commands to prevent problems. Theoretically it should work. Before the machine is finished I'll get the analog expansion module and place the drive under IP-A control as I mentioned above.
When I started researching options for the retrofit, I talked to a company stateside here called PMDX. They had provided the breakout board I used for a brideport retrofit I did a few years ago. They didn't have an ethernet control board, but they told me Brian Barker had recently purchased two of these very same machines and was planning to retrofit them both. I emailed Brian and he put me in touch with the guy who was designing his retrofits, Scott Schaffer. Scott planned to have the spindle under DL06 control. From the reading I've done, Scott is extremely knowledgable on machine design and mach retrofits. He's done quite a bit with this particular PLC. So, long story short, this is the primary reason my DL06 controls the spindle drive.
Just out of curiosity, do you know of anyone who makes a vfd that takes a + or- 10V signal?
Jonathon