Pci or Ethernet motion control?

[Doddy]

Holy thread revival!

On this subject of PCI vs Ethernet, and with a particular application of a Lathe/turning project where I need to encode the spindle speed (and possibly with >1 ppr, likely 64-200ppr), is there any experience with how the packetised nature of ethernet impacts the latency/jitter of the spindle timing pulse which would critically impact the ability to thread?

I'm thinking Parallel port or PCI before ethernet - I can't imagine how a rotational controller is going to give phase-accurate timing on the PC through the ethernet packaging and/or socket stack to give a real-time rotational speed decoding.

Or has anyone got experience of shaft position encoding with an ethernet controller? Does it work?

[Clive S]

Holy thread revival!

On this subject of PCI vs Ethernet, and with a particular application of a Lathe/turning project where I need to encode the spindle speed (and possibly with >1 ppr, likely 64-200ppr), is there any experience with how the packetised nature of ethernet impacts the latency/jitter of the spindle timing pulse which would critically impact the ability to thread?

I'm thinking Parallel port or PCI before ethernet - I can't imagine how a rotational controller is going to give phase-accurate timing on the PC through the ethernet packaging and/or socket stack to give a real-time rotational speed decoding.

Or has anyone got experience of shaft position encoding with an ethernet controller? Does it work?

There should be no problem using the Ethernet for spindle control (even a high speed encoder) as the processing is done on the card. You mentioned Linuxcnc a while back have a look at these cards 7i76e 7i96 and 7i92

http://store.mesanet.com/index.php?r...product_id=290

http://store.mesanet.com/index.php?r...11&search=7i96

Funnily enough Ross is retrofitting fitting a couple of lathes with the 7i96

Edit: PCW is the guy on the Lcnc forum that owns Mesa

[m_c]

As Clive says, it's done on the card.
All the Mesa cards I've looked at have an FPGA which will handle all the time critical stuff, and motion will be buffered to the FPGA.

It's how pretty much all external motion controllers work.

[Doddy]

Cool, m_c and Clive - that's kind of addressing my concerns. I'm still going Linux, but it's going to be the usual 4+ weeks for 2 MPGs to find their way to the UK so I'll play with PP in the short term but for the MPG encoding as well as spindle speed controllers it looks like a Mesa card is needed in the near future.