On Thursday 24 September 2009, Sven Wesley wrote: >Yes, maybe. What should I look for? > The voltage levels your parport is capable of outputting, and whether there may be extra noises on the signals. The scope will need to be dc coupled of course, and have good bandwidth. The 100mhz dual trace that most techs carry is about right for this sort of stuff.
Your parport should be capable of outputting a logic zero that is well below .2 volts, which gives about a .4 or .5 volt margin for noise. Conversely, the logic 1's should be 2.9 volts or better ttto have that same half a volt for noise margin, and here, generally speaking, the pullup ability is rather puny, so noise on the line becomes more important. There is a voltage range from about .6 volts to around 2.4 volts where the chip makers will not say what the output will be, so the driving voltages must be more widely separated in order to be running at guaranteed valid signaling voltages. Sure, one can measure this with a multimeter, but it doesn't show you the noise that screws things up. The scope will. And some parport driver chips are known to have very low driving abilities. The cure there is to use an aftermarket card, which will generally have much stronger drivers on it. 'star' grounding schemes are also good practice. Just tying all the grounds together all over the place will often cause ground loops, which can pick up large amounts of noise & muck with things in strange ways. The shield coverings of my motor cabling are grounded only at the driver terminal ends, and not to the machine, which has its own frame ground via the power cord and the variable speed spindle controller. I can even do EDM with an 80 volt, 6 amp capable supply running at 3 amps, so noisy my 75 year old ears object, but none of that noise gets into the control circuits badly enough to effect the machine. >2009/9/24 Gene Heskett <[email protected]> > >> On Wednesday 23 September 2009, Sven Wesley wrote: >> >I'm still loosing on Z by the way, I'm starting to suspect a faulty >> >> driver. >> >> Do you perchance have access to an oscilloscope? > >--------------------------------------------------------------------------- >--- Come build with us! The BlackBerry® Developer Conference in SF, CA > is the only developer event you need to attend this year. Jumpstart your > developing skills, take BlackBerry mobile applications to market and stay > ahead of the curve. Join us from November 9-12, 2009. Register > now! http://p.sf.net/sfu/devconf >_______________________________________________ >Emc-users mailing list >[email protected] >https://lists.sourceforge.net/lists/listinfo/emc-users > -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) The NRA is offering FREE Associate memberships to anyone who wants them. <https://www.nrahq.org/nrabonus/accept-membership.asp> Most people don't need a great deal of love nearly so much as they need a steady supply. ------------------------------------------------------------------------------ Come build with us! The BlackBerry® Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9-12, 2009. Register now! http://p.sf.net/sfu/devconf _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
