Re: EHP External Hardware Proposal

Steve, I just replied to your Simple Step posting...

reply in text

Steve Carlisle wrote:

> From: "Steve Carlisle" <quatsein@...>
>
> Hans, thanks for the reply. There is so many possibilities
> on this cnc hardware, it seems to confuse me at times.
> I have seen numerous PIC/Stepper IC's but they seem to
> operate fairly slowly (4800 baud).

Lots of PIC project use PIC chip without the built in UART and the simply do the bit banger software UART...
I use the PIC16C66 76 77 876 etc... The on board UART can do a very high Baud rate. beware of the early PIC16C73 it had a
silicon problem and lost data above 9600 Baud...!

> Am I right in that you want
> to make an intelligent RS232 to step/direction convertor?

YES !

>
> What software is out there that is compatible with RS232
> and not propriotry? Need that knowledge!

None that I know of, and I was expecting to do it myself, until Matt Shaver's reply.. See earlier posting.
I correct that, last year when I was researching CNC I found a company in India that had a pretty neat program, 6 axis I seem to
remember and could control
multiple machines ALL using RS-232... When I send them a message asking if the software was available for printer port output...
they said NO...

If I can find that link I'll post it ..
regards
hansw

>
>
> Steve
>
> ----------
> From: hansw <hansw@...>
> To: CAD_CAM_EDM_DRO@onelist.com
> Subject: Re: [CAD_CAM_EDM_DRO]EHP External Hardware Proposal
> Date: Tuesday, February 01, 2000 7:50 PM
>
> From: hansw <hansw@...>
>
> Steve,
> I posted several replies the details of the idea.
>
> In reply to your question...
>
> I do not see it as a board in the sense of a plug in ISA or PCI card... it
> would be external and controlled by RS-232
>
> PC-----------RS232----------------EHP-------------Exisiting Driver
> Hardware.
>
> The idea is to use RS232 much like Flash Cut... but it appears FLashCut
> are holding their system details close to the chest...
> I'm not interested in copying any ones idea, I can do it self...
> See other postings about this subject ..
>
> regards
> Hans Wedemeyer
>
> Steve Carlisle wrote:
>
> > From: "Steve Carlisle" <quatsein@...>
> >
> > It seems that most of the companys that sell data aquistion
> > and control products list, LPT/Printer port compatible I/O
> > systems. Would this be the type of board that would be
> > considered for EHP?
> >
> > Steve
> >
> > ----------
> > From: Bertho Boman <boman@...>
> > To: CAD_CAM_EDM_DRO@onelist.com
> > Subject: Re: [CAD_CAM_EDM_DRO]EHP External Hardware Proposal
> > Date: Tuesday, February 01, 2000 5:32 PM
> >
> > From: Bertho Boman <boman@...>
> >
> > More thoughts:
> >
> > I think Hans is going full speed but we need to talk about our goals.
> >
> > A few of my suggested goals:
> >
> > Keep it simple and do not reinvent the wheel. Make it possible for
> persons
> > to either use what is commonly available or easily
> > modifiable.
> >
> > To make an external multi-axis, coordinated controller board is a
> > significant undertaking. To further complicate it by adding
> > the servo/stepper amplifiers on board would be a very large task to say
> the
> > least. Besides the hardware there would be tons of
> > software required.
> >
> > Doing a one channel DSP (or Micro-P) based controller like I described is
> a
> > reasonable group project. That would separate the
> > motion control software from the servo amplifier and the tach feed back
> and
> > it would also remove the need for an expensive
> > custom PC I-O card. Actual I-O could be either through the parallel port
> > or even opto isolated RS-232.
> >
> > The software to drive it only needs to be modified slightly: Instead of
> > writing the the command to the PC I-O card D/A it sends
> > it out on the printer port or the equivalent step speed command. Instead
> > of reading the shaft encoder counter on the I-O card
> > it reads it from the printer port. I think it would be relatively easy
> to
> > modify CNC software to do the above.
> >
> > That means multiple existing software could be used with slight
> > modification since none of the timing or feedback loops are
> > changed for the software. Only the local servo constants would be
> modified
> > but they are normally external anyhow.
> >
> > Neither Hans or I are happy to have to fiddle with Linux but if the
> > installation and RT kernels issues are streamlined, EMC
> > would be an excellent choice for the software. That would also remove
> the
> > need to modify EMC to make it work well with
> > steppers. An other possible alternative would be if Hans or someone with
> > the right experience can take a look at what it takes
> > to run EMC under a slightly modified NT to get reasonable RT performance
> as
> > I mentioned in a previous post.
> >
> > A small single channel board with PWM amps that can be used with either
> > steppers or servos sounds good. Hey, stack up six of
> > them and we have a hexapod! It would solve several problems:
> >
> > 1. Pulse generator for steppers with no frequency limit or jumps
> > 2. Amplifiers for plain steppers.
> > 3. Encoder feedback for steppers.
> > 4. Servo Amps with digital gain/ filter control.
> > 5. Encoder, home and limit switches interface.
> > 6. Electronic tach for servo feed back
> > 7. No PC I-O card required
> > 8. Easy opto isolation
> > 9. Since it is a very low cost single channel board it can be used for
> > simple motion control of just about anything.
> >
> > To the EMC "crew": Is it practical what I suggest and would you be
> willing
> > to support it?
> >
> > Hans and Windows programmers: Have you taken a look at what is required
> to
> > run EMC on NT?
> >
> > Who has DSP experience?
> >
> > Step up to the mic. Let your suggestions and comments be heard!
> >
> > If this is pulled through, I can have the boards built on my production
> > lines at cost (I'm not in this to make money) as long as
> > we can run a reasonable size batch each time. That way, software and
> > non-electronic persons still can be part of a large group
> > and we can standardize our effort.
> >
> > Bertho Boman
> > =======================================
> >
> > > From: "Carlos Guillermo" <cnk@...>
> > >
> > > Hans -
> > >
> > > I've got a pretty basic question. Are we talking about offloading
> > > interpolation duties to external hardware? As in sending an arc-move
> > > command to the external micro and then letting it execute the
> coordinated
> > > motion? Or, are we talking about merely updating a count register for
> > each
> > > axis' "commanded position" and letting the external micro handle the
> > servo
> > > loop, PID gains and all? Or, are we just talking about blind stepper
> > pulse
> > > train generation...? I think I've heard a little of each from the
> > various
> > > people interested in this system architecture, and was just wondering
> > what
> > > the external micro's duties would be.
> > >
> > > Carlos Guillermo
> >
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