On Friday 29 May 2020 22:14:57 andrew beck wrote: > sweet thanks gene > > I will take your advice and connect the pc chassis to the main ground. > > I think I will continue to use my grounding blocks for now though as > there are about 20 ground cables to connect up and that is getting a > bit much for one bolt I think. hopefully I don't have a problem. I > will let you know if I do haha > Use only one block, and put them as close together as you can. > > regards > > Andrew > > On Sat, May 30, 2020 at 2:00 PM Gene Heskett <ghesk...@shentel.net> wrote: > > On Friday 29 May 2020 21:22:09 andrew beck wrote: > > > 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? > > > > The computers 3rd wire should remain if its the ONLY ground > > connection in the whole system. But since we power gear thru EMT > > tubing, and that also includes a generally better ground, the power > > cord to the computer should have that 2nd or 3rd ground removed, and > > the computers ground taken back to this common bolt by a direct from > > its chassis ground wire, UNLESS the computer is mounted to and > > mechanically connected to the frame of the machine and this frame is > > grounded to that common bolt. > > > > Anytime you can lift just one of those wires from that bolt, and > > still get ground continuity because its grounded someplace else too, > > is bad kharma, find that "other" ground and disconnect it. Once, > > done well, is enough. A shielded cable where the shield is grounded > > at the far end can inject many volts of noise, enough to blow the > > interface card. Disconnect that far end. That bolt should connect to > > the power wirings "static" ground, and the only allowable cross > > connected point to the powerline neutral is in the main entrance > > box. You don't care if a nearby lightning strike might cause that > > bolt to be 200,000 volts from ground for a microsecond during that > > strike, but the +5 volt line will be 200,005 volts, or 5 volts from > > what it considers its ground might be at that exact instant. You > > will be damaged ONLY if some other point in the circuit breaks down > > and some of that lightning bolts energy actually flows thru your > > system to get to that better ground. Block it with air, the more the > > merrier. > > > > > 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 > > > > 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
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
