RE: Interface update

> -----Original Message-----
> From: Dean Sala [SMTP:adsala@...]
> Sent: Wednesday, February 23, 2000 5:48 PM
> To: CAD_CAM_EDM_DRO@onelist.com
> Subject: Re: [CAD_CAM_EDM_DRO] Interface update
>
> From: "Dean Sala" <adsala@...>
>
> Doug,
> It's real great that you are trying to resolve this problem. I completely
> agree that we need some sort of breakout box that could get us up to speed
> faster. With an on board 5vPS, relays, screw in terminals and such. It
> just so happens that I have already designed a proto type of this board to
> work with CNCpro. Except that it does not use optoisolation on the
> board.
> I already have optoisolation on board my step drivers.
>

Most, but not all step motor drivers have optoisolated inputs. It's
those exceptions that I want to accomodate here.

> The auxillary outputs, 3 in all so far (CNCPro at least) go through
> ULN2003a's
> (that can be parralleled for more current) to drive 1amp 5v relays.
>

I though CNCPro had 4 aux outputs.

> Also, the homing inputs are hooked up to IR switches with their own
> terminal
> block. The other inputs are just tied high through 4.7ks.
>

It would also be nice to have the ability to use 120VAC for the
homing inputs. I know this sounds strange, however, some of my industrial
applications require long wiring runs that would be succeptable to noise if
5V were used. Here again, I'm talking about an option made available by
careful design of the PCB. Populate as needed.

> Are you sure you need optoisolation on the board too? I can add them
> right to the output of the SN74S244 but
> then the opto isolators would be driving opto isolators. Maybe I can put
> a
> switch selector to bypass opto isolation if the step drivers have them.
>

Again, these would be a populate as needed option.

> Possible enhancements: On board 5V power supply(otherwise supply external
> 5v
> PS). Connectors to connect 120v to stepper power supply with fuses etc.
> Diagnostic LEDs connected to various outputs. Connectors for main power
> switch and power light. Oh, limit switch connectors tied to turn off
> stepper PS. There you have it! All-in-one wonder board!
>

Agreement.

> About using the parrallel port for drive LED's....you should sink them of
> course but it's always better to put a buffer inline like an S series TTL
> driver which can source 28ma and sink 64ma perfect for this situation,
> more
> noise resistant and just what their made for. This way you don't have to
> worry about how much power the parallel port can provide.
>

Also agreed.

This newsgroup is made up of enthusiastic, knowledgable people. We
share a personal interest in what we do. However, I have industrial
applications for this board. Industry is heavily populated with disgruntled
workers that seem to enjoy trashing things. Having built test equipment for
production workers I can tell you that idiot-proofing (they call it
industrial hardening) is an absolute must.

I see an all-in-one wonder board with lots of holes in it. Some of
us want optos. Some want on-board power. Etc - etc. Let's design a PCB
layout that will provide all of this in any combination the builder desires.
More of us would build things if we didn't have to fiddle around with all
those darn wires. I'll put up the money for the boards and parts because I
have industrial applications for it outside of CNC. Then if anyone on this
list wants one I will pass it on at my cost. Sound fair?

Doug