Here's my test setup.
from left to right.
1. MESA 7i92H connected via Ethernet to the Pi4 1Gb sitting under my monitor.
The Pi is running LinuxCNC.
2. Probotix Break out Board and although it could be isolated I'm using the
same 12V supply for both sides with the BLK/WHT twisted wires.
It generates the 5V to run the MESA 7i92H. BLK/RED twisted wire.
3. The PWM Spindle Control board I pulled from the mill because I was too lazy
to assemble another one for this testing.
It too is powered from the 12VDC adaptor (actually more like about 16V)
Grey jacket cable to black connector.
This holds the little PWM to 10V module and is driven by the BoB via DB25
pins 14-PWM, 16-DIR and 1-ENABLE
4. Bergerda AC Servo showing that it's running the motor at 558RPM which I set
from the LinuxCNC buttons.
Now the first surprise when I stopped the LinuxCNC program. I've been spoiled
by the ChargePump on the PMDX-126 BoB I use. With this small Probotix board
the program stopped and the parallel port output pins all went high. Not a
problem for a stepper motor. Big issue when the PWM input thinks that is 100%
and the ENABLE signal which is active high goes high. Motor started turning at
full speed.
I'm not surprised. So many of the Break Out Boards out there are designed only
with stepper motors in mind but in this case this is the spindle. This enable
signal would also run a master power relay which would also stay on after
LinuxCNC went away. Not good.
With the Charge Pump gone the Break Out Board automatically disables outputs so
they can't source current out to a drive and it definitely switches off any
relays on the BoB. So not too impressed with this small BoB.
Or maybe the issue is with the 7i92? Perhaps on loss of communications with
the host it should set the outputs low. It's looking like it sets them high
since the PWM output was 0 and the ENABLE output is also LOW set by the "Toggle
Machine Power F2" button on the user interface.
> -----Original Message-----
> From: R C [mailto:[email protected]]
> Sent: June-14-21 8:14 PM
> To: [email protected]
> Subject: Re: [Emc-users] all the MESA cards talk made me think
>
>
> On 6/14/21 3:50 AM, andy pugh wrote:
> > On Mon, 14 Jun 2021 at 02:16, R C <[email protected]> wrote:
> >
> >> I have seen the 7i92� mentioned, and others,� can they do multiple
> >> stepper motors?� (right now I am using a parallel BOB,� that connects
> >> to� steopper drivers (ala DM542), which drive the actual steppers.)
> > The Mesa FPGA card replaces the parport card, and in some cases also
> > replaces the BoB.
> >
> > The 5i25 and 7i92 replace only the Parport card and would retain the
> > same BoB. They can both be used with the same BoB as you currently
> > use, or you could use a 7i76 (probably overkill)
>
> right I have been looking at some.� I don't mind using existing BOBs,
> since I have several, and since I am not really running high-tech,
> industrial stuff..� it shouldn't be too expensive.
>
> (I saw some between 50-100 bucks, that would work (?)
>
>
> >
> > Alternatively you could look at a 7i96 or 7i76E which both connect to
> > the ethernet port and replace both the parport card and the BoB.
>
> I'll look into those too.
>
> I wonder how these things need to be programmed though, John explained
> some of that.� I think in a bit, when I have more time, I� just buy a
> few and just jum in (but build a test setup first.
>
>
> Ron
>
>
> > There are not any PCI cards which also directly replace the BoB, and
> > none that replace the stepper drivers.
> >
>
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