Re: [CAD_CAM_EDM_DRO] EMC2 Servo Loop

Phil@Yahoo wrote:

> This is a question mainly for Jon Elson, being the EMC2 guru-
>
> You mentioned in a recent post that EMC2 can run the servo loop in the PC,
> which I presume means the PC is reading the encoder outputs. My question is:
> how can the PC read the encoder fast enough? I know there are some fairly
> significant delays in the parallel port speed, at least on output. Maybe
> that's not an issue on input? Also, where do you get enough inputs?
>

Maybe I should expand on my previous message....
The idea here is that the attached hardware counts the encoder pulses
and converts them to
position. In the case of my boards, that is a 24-bit signed binary
count. This is then extended
by the device driver to give 32-bits of signed precision, which nobody
so far has found
insufficient. So, the computer only needs to sample the count
periodically and compute a
new velocity to minimize following error.

Jon