Re: [CAD_CAM_EDM_DRO] Re: PC to controller comunication protocols

Hi Jack,

Yes! That's interesting. But why the "added" noise? Race conditions
perhaps?

I developed and am using my own CNC controller, STEP4. I'd be
interested in hearing more about yours.

Alan KM6VV


jcc3inc wrote:

>Gentlemen:
>
>I too have been working (off and on) on a CNC controller. It is DOS
>based with a max step rate of 4.166 KHz. It does work well, but I'd
>like to have available a higher step rate, and a smoother output
>pulse train. The current max pulse jitter is 240 microsec.
>
>I've been working on an external curcuit which accepts commands of
>up to 31 steps from the parallel port and does linear interpolation
>in X, Y, Z from the sequential commands. The base update rate is 1
>KHz, so there's time for the computer to do other tasks such as
>velocity smoothing and cutter comp. My current IC external circuit
>has added "noise" pulses at the rate of about 12 or so per 100,000
>pulses, not acceptable. So far I have not eliminated the noise. The
>supporting PC program for the above with linear and circular
>interpolation is done, and appears to be OK. The objective for the
>new approach is 31KHz pulse rate and a jitter of 30 microsec or less.
>
>If I knew something about programming microprocessors, they would be
>a better possibility, as the code to handle linear interpolation for
>3 axes is simple, in BASIC anyway. My programming experience has
>been only in QuickBASIC.
>
>I'd be quite interested in communicating with others of similar
>interests. A spec sheet and screen view of my controller are
>available. I could post them in the files and photos section here.
>
>Regards,
>Jack C.
>
>