RE: Interface for CNCPro, etc.

> -----Original Message-----
> From: stratton@... [SMTP:stratton@...]
> Sent: Monday, February 21, 2000 8:42 PM
> To: CAD_CAM_EDM_DRO@onelist.com
> Subject: Re: [CAD_CAM_EDM_DRO] Interface for CNCPro, etc.
>
> I was just going to socket the chips and use them as spike absorbers,
> but I suppose optocoupling could be done.
>

Sockets are incredibly cheap and should be used for all home brew
boards IMHO.

> having standard off-the shelf cables coming from the card, so that the
> computer can easily be disconncted from the amps. Then have simple
> passive breakout boards that could mount in the amp enclosure and go
> from DB25's or whatever on the cable to screw terminals.
>

How about making the card so either a DB25 or removable screw term
connector can be fitted during solder-up?

> Are you sure the parallel port can't drive an optocoupler? It may not
> be in spec, but I've never had any problem driving visible LED's from
> one.
>

The original IBM spec called for about 5ma sourcing and 25ma sinking
on the data lines. The control lines are supposed to have less capacity. I
talked to a colleague today about this (former IBM research lab manager).
His guess is that newer one-chip parallel ports have even lower source/sink
capabilities. Does anyone out there have good data on this?

Doug