4th axis build - Can I use Mitsubishi Servo Motor HF-SP102 (1kw) via SSCNET-III

I’m in the process of building a 4th axis for my linuxcnc mill.  My Mill is a Matsura MC-500 and is based on MESA boards via ethernet and QT dragon w/Linux 2.9.
I’ve aquired for cheap two new HF-SP-102 motor (1KW) with high load and high precision harmonic drives from "Harmonic Drive LLC" that are integrated (but can be separated) for $25/each, I then found the servo driver for it MR-J3-100B amp on ebay, and got the cables to connect it for a few hundred.
I’m now trying to work out how to connect it to the PC and drive it but it doesn;t seem that straight forward as the servo driver support SCNET-III.  I saw some posts and links to Dimitry's site(www.yurtaev.com/), but my PC is an all in one touch screen and I;m not sure it has PCI slot.
I perhaps I could get a MR-J3-100A driver as it uses a 'general' interface (not SCNET-III)

I probably got a bit excited with the cheap motors and gear boxes and just assumed it would be straight forward to get the electricals working (oops).  What do you think is the best way forward?  Buy a card from Dimitry and a new PC and touchscreen, or should I get a different path that is supported by the MESA boards and non PCI ie buy a different motor+servo and make the adapters to the Harmonic reducer units I have.

Cheers,
Cam

A cursory look through the manual (I think it's the right one) looks like the MR-J3-100B can also take +10v/-10v analog input control.

If so - and you'd better make sure I'm not way wrong - you could use a Mesa analog board to control it.

On the other hand, if you're using step/dir for you other drives new servos are getting so cheap it might make sense to just buy a new one and fit it up.

Side note - when I put a servo on my 4th, I found it extremely helpful to have a very precise home-to-index function.  Really cuts down on the typical fiddling getting a trunion table or vise dialed in.

Whatever servo you wind up with, try to ensure it's got an encoder index signal output, and you've got a couple free inputs (one high speed and one for a home proxy).

Thx Spumco,
You're right I could use the 10v but I don't think this will give good positioning accuracy, would be fine if I were using it in a lathe like situation.
I've found another servo driver which has step dir pulses, its their A series of servos (MR-J3-100A or MR-J4-100A),k the B series seems to be SSCNET series. I might try and chase down one of those.

I assume you posted some info on your 4th axis build so I'll do some reading up on the homing.

Thx Aciera, thx re the driver recommendation. Also I didn't know about the encoder delay kinda important, as I would like it to be accurate for longer machining runs I'll look into adding an external encoder as you suggest.

camb0 wrote:

I assume you posted some info on your 4th axis build so I'll do some reading up on the homing.
 

I can't remember if I did or not, but the homing wound up being pretty convoluted because I was out of HS encoder inputs and had zero room to stuff another Mesa board in the enclosure.

• Solution - use the drive's internal home-to-encoder-index function (Copley XSL)
• I wound up using some relays and HAL logic so that when I pushed the "Home-A" button
  • LCNC sets home (i.e. G53 A0) without commanding the drive to do anything
  • joint.3.homing sends an output to trigger the A-drive to home itself
  • When the drive finishes homing, it sets an output that's connected to joint.3.home-sw-in

It works, and is like a low-tech version of the absolute homing the Ethercat folks use to 'trick' LCNC in to behaving with hardware capable of external homing.