Wonderboard PC interface original message!

It seems as though this thread has went off on a tangent. I originally replied to Doug about a parrallel interface card that I had designed to work with CNCpro. But it seemed to never appear on the message board except in Doug's reply to it. The reply is in the "Interface Update" thread. Anyway, It seems as though some of you are getting confused between what Doug is proposing and what I have done. So I want to clarify. I designed an proto typed external interface card to work with CNCpro. I am building a homebrew CNC system so my design is catered towards that. I believe Doug has different requirements and is building a more robust board catered towards industrial use. Am I right? I'm not completely clear about his requirements yet. But this is what I wrote to him.


Here is my original message to the "Interface update" thread.

------------------------------------------------------------------------------------------------------------------------------
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.

The proto type plugs into the parrallel port via cable. It has it's own
DB25 connector on one side and has a series of screw terminals on the other.
It consists of a SN74S244 hex schmit trigger driver to drive the step and
direction data (3 or 4 axis or whatever)into the Step motor drivers. 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. 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. I am still
working on the design and am thinking about making it more universal for
other parrallel port NC programs that aren't as configurable as CNCpro. But
first I'm keeping it simple. I'm sorry for not getting ideas from you guys
but now I have a feeling what you want. 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.

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!

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.

Good luck
Dean

---------------------------------------------------------------------------------------------------------------------------------------

Please read Dougs reply in the "Interface Update" thread if you are interested in his comments. It is a message stored under his name

If you have any questions about my design please reply. I left a few things out of the above description.

Thanks
Dean Sala






[Non-text portions of this message have been removed]