Re: [CAD_CAM_EDM_DRO] Re: Black box

ron ginger wrote:

> I really want NO critical time constraint on the PC. With a smart box,
> I send it off on a move, and the PC can go out to lunch, that move will
> accelerate, count to its end and decelerate exactly as programmed. Your
> approach lightens part of the load on the PC, but still keeps it in a
> tight time loop.
>
> I suspect the cost of the box is really unrelated to its smarts. Clearly
> this work can be done with a PIC, because Kerr sells a box that includes
> a servo amp in it for just under $200. I suspect most of the cost is in
> making a board, adding connectors, etc, and putting it in a box. The
> exact compliment of chips in the box probably doesn't change the price
> much.

But, then you can't follow a path consisting of a series of small vectors
at a constant feed rate, which is an awfully nice feature to have. So, you
at least need to have the capability of making a move and keeping going
to merge smoothly into the next move. Of course, if the PC doesn't
service the motion system, then you have an axis sailing off into the
wild blue, or requiring an abrupt stop at the endpoint. I think you
have to deal with the problem of ASSURING that the PC can continue
to service the motion control with a steady stream of commands, or
else it is really a toy CNC.

Jon