Re: [CAD_CAM_EDM_DRO] Re: Re: EMC, ISA and other Questions...

alex wrote:

>Ray,
>I made a program to transmit DRO data from Mauch/Kulaga board to another
>machine in real time.
>
>It can be helpful if Linux machine doesn't have ISA slots, then it can be
>networked
>to a cheap old computer which does DRO readout. Then closed-loop operation
>can be facilitated.
>

No, you are dreaming. A DRO is fine for a person who can handle 2 or 3
updates a second.
Closed-loop motion control requires very repeatable sampling intervals,
because velocity
is calculated from how much the position changed sinde the last update.
If the interval of the
samples, or the interval of the packets transmitted, varies, the program
is unable to give
predictable speeds. I run EMC at 1000 samples/second, with less than 10
uS of jitter in
the sampling interval. Most commercial CNC systems have very high
sampling rates,
from 10 KHz to 60 KHz and above.

If there is nothing else but the 2 computers on the ethernet, this might
work out OK, but
even with that limitation, the time of packet transmissions may not be
dependable.

Jon