Re: [CAD_CAM_EDM_DRO] steppers+feedback+emc

awallin25 wrote:

> after milling some mdf with a stepper controlled table I think i need
> to add feedback(encoders) to eliminate missed steps...
>
> my question is:
>
> would it be possible to hook up the encoders directly to the pc and
> let EMC read them and act accordingly, ie. implement a PID controller
> in (real-time) software ?

No. The problem is that the PC would have to sample the encoder signals
many thousands of times a second to avoid missing a transition. Much better
to have a counter in hardware than never "looks away", but is dedicated to
wathcing the encoder position.

> the parallell port pins won't be enough(?), but what other options
> are available ? (serial?)

In general, the serial port is too slow.

Take a look at my latest project http://pico-systems.com/univstep.html
it has the encoder counters, plus very smooth step pulse rate generators,
plus the digital I/O for limit and home switches.

Jon