> -----Original Message-----
> From: Les Newell [mailto:les.new...@fastmail.co.uk]
> Sent: February-07-20 4:40 AM
> To: emc-users@lists.sourceforge.net
> Subject: Re: [Emc-users] Homann Designs ModIO
>
> > With how cheap realtime i/o is - I don't see the a lure of modbus.
>
> Modbus non-realtime should be plenty fast enough for spindle control
> unless you are doing position control of the spindle. I'm not sure about
> RTAI but if you are using preempt-rt mb2hal should be pretty close to
> real time.
>
> It's also great for user interface stuff. For instance both my mill and
> lathe have Modbus front panels with 20+ buttons, numerous indicator
> lights as well as a number of analog controls.
>
> For jog wheel I have to agree, a direct realtime input is the way to go.
> Modbus jog wheel should work but it won't be as smooth.
>
> > It's a bit unusual in that mb2hal consumes an INI file, but it is not
> > the same INI file as defines the LinuxCNC machine config.
> You can specify the machine config ini file if you wish. The mb2hal ini
> file namespace does not conflict with anything else in the machine config.
>
> Les
>
Under MACH3 now that I finally have the ModIO MPG working I can report that
it's not as smooth as my USB based pendant. But then 56k baud isn't the same
at 6Mbps that USB uses.
I would imagine if I connected the quadrature MPG knob directly to a second
parallel port I'd also see better response in MACH3.
But that requires adding a low profile PP board. The one I have I works under
WIN-7 but not WIN-XP (it's just too old and no drivers exist) and IIRC, I had
problems discovering it under LinuxCNC too. Hence the purchase of the the MESA
7i92H.
Anyway, first step is just to get the MODBus stuff working and the ModIO is as
good a product as any. Long term I want a CAN bus on my mill for tool changing
etc. But that's because I have been using CAN bus for almost 30 years and I
believe still have the record for the largest one shown on my home page (over
1500 nodes).
http://www.autoartisans.com/
John
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