Re: PC based CNC system architecture

Jon Elson <jmelson@a...> wrote:

>
> > Wally K. wrote:
> > This was kind of what i was getting at. You have made a specific
> > design for 1 customer and now everyone has to live with those
> > wants and needs.

> Jon Replys:
> Yes, but so did the guys who designed the LS7166 and 7266.
>

I did not follow you here. What is a LS7166 and 7266.

> >
> > > >Wally K wrote:
> > > >
> > > > 3) it will be fairly expensive. From memory $350.00 or so.
> > >
> > >Jon Elson wrote:
> > >
> > > The particular customer wanted nice Phoenix Contact plug-in
> > > terminal blocks, and some other stuff that ran up the cost, also
> > > needed differential input option, etc...
> > >
> > > A different design should be able to be done using the same

basic

> > > chip such that the entire counter and rate generator would fit

on

> > > one board. I think the only other part would be the crystal
> > > oscillator. We also did a fancy 8-slot motherboard for these
> > > cards, but again, there are much cheaper ways to go, like
> > > eliminating the gold card edge fingers.
> > >
> > > These prices were based on buying 15 PC boards, first time
> > > (so it incurs the setup charge) and parts for about 5 of each
> > > board. Even small increases in volume make a big difference,
> > > especially in the PC board cost.
> > >


> >
> > Wally K. replys:
> >
> > Jon you have been with this group far longer than i have. From

your

> > experience with this group wouldn't you say the people here range
> > from thrifty to cheap (not that there is anything wrong with being
> > either).
> >
> > After reading Matt Shaver's post about selling this unit for

$800.00

> > to $1000.00 i darn near fell off of my chair. I would say with

that

> > price Matt has put this control out of reach of at least 90% of

the

> > people that would want it.
> >
> > I would really like to see your schematic of this control with the
> > sections needed for stepper control marked. I would like to see

if i

> > could make a new layout and or make different component choices

for a

> > low cost stepper control.



> Jon Replys
> The first batch of boards cost $57 each! Now, if we don't need to

revise

> them, and we buy a larger quantity on a reorder, we save a bundle!
> About the only component change you can make is the terminal
> strips. There are $36 of Phoenix Contact pluggable screw terminals
> on this version. Much cheaper terminals should be available,

although

> these are 2.5 mm spacing in this design. The only other expensive
> part is the Xilinx XCS10-PC84C FPGA, at $18.10 (and I was forced
> to buy 15 of them!) There is a $6 SPROM to load the configuration
> into the FPGA, one 74HC00 gate for startup and a crystal oscillator

module.

> That's all there is on the board, if you don't want differential

inputs.

> This and a few decoupling caps comes to $126 - it adds up quick.
>
> I added a few extra traces on the board so that the same board could
> be used with a different chip configuration as a 4-channel rate

generator.

> That is still a concept only, but I'm pretty sure I can make it

work in

> the same FPGA.
>
> Jon
>

Wally Replys:

I need a little help understanding your overall concept here. From
what you say in this post and trying to remember what you said in
previous posts. Is the $126 configuration all that is needed for
stepper control for 4 axis. Or are other cards needed. You have
talked about a motherboard with 8 slots in other posts, is this $126
card the motherboard. Are the 8 plug in cards you talked about for
servo control only.


Wally K.