It's been a long time and I have not made much progress. Except now I am
retired from my job as an electrical engineer. In my job I developed
industrial PMAC servo drives for a leading industrial controls manufacturer
located in Milwaukee. So to solve my servo amplifier problem I have decided
to build my own and have already made significant progress. My homemade
drives will be able to run either DC brush motors or in the future AC
motors. I have a basic torque mode drive in the process of development but
I am thinking I would like the drive to be a velocity mode drive.
My question now is how to interface to LinuxCNC? I really want to connect
all of my I/O using the mesa ethernet cards like the 7I80. From the 7I80 it
looks like there is a way to have SPI interfaces. It seems like the SPI
would be one way to make a simple digital interface to my drives. The 7I80
would send velocity commands and velocity feedback to the drives. The
drives would return status and fault information back to LinuxCNC.
Is it possible for me to use the SPI interfaces with LinuxCNC in the way I
have described? If so, how does one go about setting up the SPI interfaces
and defining what data is passed back and forth? I am hoping Andy Pugh, PCW
or someone that knows can comment.
LinuxCNC <--Ethernet--> 7I80 -----<> I/O inputs and outputs
|-----<> SPI comms to
servo amps 7I46?
| ----< encoder inputs for
axis and MPGs
LinuxCNC with position loop only should be able to run with a slower 1mSec
or maybe 500uSec thread and no other high speed thread would be needed. I
may however need to get the velocity feedback to my servo drive at a faster
rate for best/better performance.
My reason for wanting Ethernet is I do not have to have my LinuxCNC PC on
or embedded in my machine, it can be several meters away mounted where it
won't be subject to heat and vibration. In addition with only one
interface, a PC upgrade or repair / swap is easy.
Regards,
John Figie
On Sun, Nov 29, 2020 at 6:47 PM dave engvall <dengv...@charter.net> wrote:
>
>
> On 11/27/20 10:52 AM, andy pugh wrote:
> > On Fri, 27 Nov 2020 at 18:45, John Figie <zephyr9...@gmail.com> wrote:
> >
> >> I think I am going to attempt to figure out what the parameters of my
> motor
> >> are and make a model to simulate my control loop. For hobby stuff I
> think
> >> LTspice may be good to model and simulate.
> > I am not sure what you hope to gain from a model. The data to populate
> > it would have to come from the actual machine, and at that point you
> > might as well just get on with it.
> >
> IIRC early versions of emc had motor parameters, etc tacked on the the
> end of the parameters for each axis. I don't know if any use was ever
> made of that.
> Maybe some of the early emc-ers with their memory still intact will
> remember as well as a model to insert the data into.
> Dave
>
> Just a comment: I've never had much success using torque mode: that
> doesn't mean I should not go back and revisit it.
>
>
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