Re: [CAD_CAM_EDM_DRO] Re: EMC spindle speed control

On 18 May 2001, at 21:20, Jon Elson wrote:

> Marty Escarcega wrote:
>
>
> Oh, this is all there, and has been for 2 years or so. I have the
> forward and reverse hooked up through the parallel port, an Opto-22
> type SSR board, and to my VFD. I don't use the brake signal, as my
> VFD determines the braking cycle all by itself, and has no brake
> command. It will apply AC, and then DC braking every time the run
> signal is turned off. There is a separate output pin on the parallel
> port for forward, reverse and brake. So, you can hook up SSRs in the
> manner you choose to command power contactors. I'd wire some sort of
> interlock contacts so the forward reverse and brake relays are
> mutually exclusive, as closing any two at once could cause a dead
> short, and weld the relays.

I was thinking of the commercial FWD/REVERSE Contactors that
came with alot of machines, which are interlocked.

> > Now the spindle speed control, only think I can think of is to use
> > the control input of a VFD. Once set, don't the VFD's remain pretty
> > constant? Feedback would be another issue. Only think I could think
> > of is a rotary encoder like the one Dan Mauch sells to provide
> > feedback to EMC/Computer.
>
> EMC definitely doesn't have any provisions for feedback on spindle
> speed to close a spindle speed loop. If you have a spindle encoder,
> it can take a reference off that to do threading operations on a
> lathe, making another axis follow the spindle at some ratio, also
> known as "electronic gearing".

But again, EMC doesn't have feedback provisions for the spindle
speed....yet? :-)

> > > So, am I way out in left field? :-) Or reasonably close to home
> > plate?
>
> The particular parallel port pins for spindle forward, reverse and
> brake are specified in the .ini file, in the [EMCIO] section. IE.
> spindle_forward_index is the bit number on the parallel port that
> commands the spindle to start running forward.
> Spindle_forward_polarity sets what polarity of that bit is intended to
> mean start the spindle.
>
> Jon

Do I read right that these assignments are on the second parallel
port? And have something to do with BRIDGEPORTIO?

Thanks Jon,
Marty