thanks guys just one question about all this gene
why do you suggest breaking the ground off the the computer powersupply cable and connecting a ground from the pc chassis to the machine main ground? does the grounding that goes through the cable now good enough? regards Andrew On Fri, May 29, 2020 at 11:53 AM Leonardo Marsaglia <ldmarsag...@gmail.com> wrote: > > > > Connect all grounds to this bolt, checking that they are not grounded at > > the far end. By doing this, you are establishing a single point ground > > that is the zero volt reference for the whole system. Connect this bolt > > to the building static ground, the bare wire in most power cabling. > > > > Connect the machines frame to this bolt. > > > > Connect the - rails of all supplies to this bolt. > > > > Connect the - terminals of all cards to this bolt. > > > > Break the 3rd pin off the computers supply cable and connect the > > computers chassis to this bolt. Power the computer not from the wall, > > but from the same power feeding this box. > > > > Connect the shielding of all shielded cabling to this bolt. Do not > > connect the far end of this shielding to anything that is otherwise > > grounded. > > > > By making sure these grounds are not connected anyplace else you are > > breaking any ground loops which can and will act as antennas to insert > > noise into your control signals. > > > > By having this single point ground, a nearby lightning strike can inject > > a 100k volt pulse into the system ground as what would be called > > a "ground bounce", but the system will not see it as noise nor be > > damaged, because everything is bouncing in unison. > > > > Regardless of what that bolt does during the strike, the 5 volt supply > > remains at 5 volts to this bolt, and the 24 volt supply remains at 24 > > volts to this bolt. > > > > And when the storm is done, your chances of having anything damaged is > > reduced to the vanishing point. > > > Thanks for this Gene. It's more than useful to remember how to properly > ground logic circuits to avoid external noise and dangerous voltage spikes. > > El jue., 28 may. 2020 a las 20:35, Gene Heskett (<ghesk...@shentel.net>) > escribió: > > > On Thursday 28 May 2020 18:36:10 andrew beck wrote: > > > > > hey gene > > > > > > sorry for the slow reply > > > > > > just getting to this grounding thing now. > > > > > > currently I have single large copper block with a lot of holes in it > > > for terminals, this is connected to the earth(ground) wire that goes > > > back to the whole shed main ground wire rod in the dirt > > > > > > all my servo drives and vfd main grounds go back to this point as do > > > all motor grounds etc. this is how heidenhain set up the machine > > > originally and they have a whole grounding schematic showing how it > > > all works. I have basically copied that. > > > > > > I have 2 meanwell 24v powersupplies that have the ground wire on the > > > input side also connected to ground. the output side (phase and > > > neutral) are floating relative to ground and not connected to ground > > > at all I think. as the meanwell switching powersupply output should > > > be isolated from the input. I think this is correct > > > > > > the computer cord ground wire is currently connected to this same > > > large copper block. > > > > > The sheer bulk of that copper bother me a bit because it can function as > > an antenna. A single bolt, tightened well into the chassis with all the > > connections stacked up on this bolt will be quieter. > > > > > my computer via the 5i25 currently supplies 5v logic power to the 7i76 > > Thats fine, but if using a std bob on the other 5i25 port, do NOT enable > > the jumper for that port as the bobs std grounding will short circuit > > that, you must supply a separated 5 volts to that bob, or plug in a usb > > cable to steal it from the pc's usb circuitry, > > > > > > and one of the 24v meanwell powersupplys supplies the 24v field io for > > > the 7i76 > > I have all supplies - outputs tied to ground. It might work 99% of the > > time without it, till the first nearby lightning strike... With all > > that grounded, it will probably keep right on working after the strike. > > > > > my encoder problems started when I connected up the servo drive > > > simulated encoder output to the 7i76 encoder counter. I haven't > > > connected the 5v and 24 v grounds together. they did work for awhile > > > but don't now > > > > Tie the -'s to the ground bolt. Then do a full powerdown on the whole > > thing, with about a 10 count in the dark, then boot everything back up > > and test it. And report what you get now... > > > > > I have a 7i89 and 7i84 coming soon and will need a external 5v > > > powersupply anyway i think so will change when they arrive here from > > > america. > > > > > > anyway I read your reply and got a bit confused could you read my > > > email here and let me know what I need to change and why I should do > > > it this way just so I understand. > > > > Basicly, your lack of a common ground has possibly allowed voltages well > > above the breakdown voltages of the chips on these cards, between the - > > connections and a real ground. They all have what can look like an SCR > > as an isolation tub under each transistor its built from, and these > > SCR's can upset the whole thing if they get turned on. Thats why the > > count to 10 or more powerdown is done, giving these SCR's time enough at > > a low enough voltage to turn them off, at which point the circuit looks > > more normal and may even work. If not, then something has been damaged > > on the card and it should be replaced or tested and repaired as needed > > by Peter. His turnaround time from CA to WV here in the states has been > > very good. Its several thousand miles. But if I recall correctly, you > > are not exactly local. > > > > > regards > > > > > > Andrew > > > > > > On Thu, May 21, 2020 at 9:31 PM Gene Heskett <ghesk...@shentel.net> > > wrote: > > > > On Thursday 21 May 2020 01:57:06 andrew beck wrote: > > > > > hey peter > > > > > > > > > > I had a look and the unless there is a shorted out pin in the > > > > > servo drive connector itself I think the wiring is all good. > > > > > > > > > > and I highly doubt the servo drive has problems all I did was > > > > > connect the 24v back into the servo on pin which is how it has > > > > > been running for the last ages. > > > > > > > > > > anyway how do you recommend commoning the grounds? > > > > > > > > > > it is as simple as connecting the field power 0v ground with a > > > > > wire to the logic power 0v ground? > > > > > > > > Yes, but how you do it can be very important. > > > > > > > > In your control box, install a longer bolt, #6 or #8-32 to the > > > > chassis. 4mm if metric. > > > > > > > > Connect all grounds to this bolt, checking that they are not > > > > grounded at the far end. By doing this, you are establishing a > > > > single point ground that is the zero volt reference for the whole > > > > system. Connect this bolt to the building static ground, the bare > > > > wire in most power cabling. > > > > > > > > Connect the machines frame to this bolt. > > > > > > > > Connect the - rails of all supplies to this bolt. > > > > > > > > Connect the - terminals of all cards to this bolt. > > > > > > > > Break the 3rd pin off the computers supply cable and connect the > > > > computers chassis to this bolt. Power the computer not from the > > > > wall, but from the same power feeding this box. > > > > > > > > Connect the shielding of all shielded cabling to this bolt. Do not > > > > connect the far end of this shielding to anything that is otherwise > > > > grounded. > > > > > > > > By making sure these grounds are not connected anyplace else you are > > > > breaking any ground loops which can and will act as antennas to > > > > insert noise into your control signals. > > > > > > > > By having this single point ground, a nearby lightning strike can > > > > inject a 100k volt pulse into the system ground as what would be > > > > called a "ground bounce", but the system will not see it as noise > > > > nor be damaged, because everything is bouncing in unison. > > > > > > > > Regardless of what that bolt does during the strike, the 5 volt > > > > supply remains at 5 volts to this bolt, and the 24 volt supply > > > > remains at 24 volts to this bolt. > > > > > > > > And when the storm is done, your chances of having anything damaged > > > > is reduced to the vanishing point. > > > > > > > > Stay well Andrew. > > > > > > > > > > Cheers, Gene Heskett > > -- > > "There are four boxes to be used in defense of liberty: > > soap, ballot, jury, and ammo. Please use in that order." > > -Ed Howdershelt (Author) > > If we desire respect for the law, we must first make the law respectable. > > - Louis D. Brandeis > > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
