Re: control panel

[Ray Henry <rehenry-at-up.net>]

On Wednesday 06 November 2002 01:26 pm, John Kasunich wrote:
> Ray Henry wrote:
> > There are also better solutions for digital IO than a spare
> > parport.  I just got a Measurement Computing (www.mccda1.com )
> > DIO-24 PCI card for some tests here.  I am able to get Linux's
> > /proc/pci to locate it for me and can use iosh to read and
> > write to it.  This means that PCI boards should be able to
> > be used in these kinds of projects.
> >
> > There are a number of ISA cards that will do similar tasks.
> > One interesting (inexpensive) set of boards can be had from
> > http://www.winfordeng.com/products/crd155b.html for less
> > than $75.00 but I haven't had a chance to try them yet.
> > This card uses a 25 pin parport connector and they have an
> > inexpensive screw terminal interface card with some prototype
> > area as well.
> >
> > There's got to be a good "industrial" approach to IO that
> > gets us beyond the extra parport.
> >
> > Ray
>
> What about the expanded I/O capabilities of the "EPP" mode of
> most parallel ports?  Relatively simple external hardware can
> allow a single parallel port to access up to 256 input ports
> (2K digital inputs) and 256 output ports (2K digital outputs).
> Software overhead can be quite low, and the hardware can be
> very simple as well.  Two input ports and two output ports
> (16 input bits and 16 output bits) would require two 74xx374s
> and two 74xx244s, plus one or two glue gate packages.  Expansion
> beyond two ports would require one '374 as an address latch, and
> some decoding.  A pair of 74xx138s would be sufficient to decode
> eight ports (64 bits of input, 64 output).
>
> I believe this is what Jon Elson is doing with his PPMC boards
> and universal motion controller.  I am planning several CNC and
> robotics projects (if I ever get the time to work on them) and
> EPP is definitely the way I am going to go.
>
> Some good info about EPP is at:
> http://www.beyondlogic.org/epp/epp.htm
>
> John Kasunich

Hi John

Yes you are correct that epp and ecp are more compact and efficient ways 
to transfer info from a pc to external hardware.  Jon E's stuff is 
designed to do exactly that.  Jon has setup and tested some software mods 
that allow the real-time and IO streams to be mixed into a single channel 
so that a single EPP can handle both types of data.

An external EPP board for IO is really attractive because it can allow 
for a single cable between the PC and that card and at the same time 
allow for many add on expansions.   

I guess what I'm looking at is a lower level of interface for those of us 
who have some wiring skills but not those needed for any higher order 
external interface card.

Good luck on the robotics projects.

Ray