Re: [CAD_CAM_EDM_DRO] Re: Having problems with Lindsay design DRO... Could you please help?

> Well, I'm still stuck.
> I have adjusted the "Time" setting and it got a little better, but it
> still has alot of errors. If I go VERY slow, it will work fine, but
> that kinda defeats the purpose of the DRO.
> I have checked all the items mentioned, and they appear to be correct.
> I am using an old Compaq pentium 75 MHz PC.
> Could it be the cable between the black box and the computer?
> It doesn't appear to be damaged, but could this be the problem?
> I think a new cable will cost about $15. Should I just cut my losses
> and buy the pre-wired board from Camtronics and use the Kulaga
> software? (I really don't want to put $85 more into this if I don't
> have to.)

Buy the kit or build it yourself - it's not a complicated circuit - I
built it up on an old prototype card in an evening, although I'll
probably spring for an etched board at some point to make it more
robust. The main point is that the circuit uses a $25 chip to handle
all the time critical pulse-counting tasks, wheras a software based
counter can loose pulses if the processor's time isn't properly
prioritized between its numerous tasks. That is a requirement that is
hard to achieve with everything going on in a modern PC, and darn near
impossible once you add the overhead of something like windows or
linux (your only safe choice is a realtime extension, like EMC uses).

Go with the hardware solution - some better wire probably wouldn't
hurt, but if your leads are moderately short and you get errors even
with your machine's spindle motor off, chances are it's timing not
noise.

Chris

--
Christopher C. Stratton, stratton@...
Instrument Maker, Horn Player & Engineer
22 Adrian Street, Somerville, MA 02143
http://www.mdc.net/~stratton
NEW PHONE NUMBER: (617) 628-1062 home, 253-2606 MIT