actually just another question here gene so following along that analogy you made with the single bolt for all ground wires. if I connect the pc case to the bolt and also the 0v from 24v dc outputs,
does that mean that I don't have to connect between the mesa 7i76 field io 0v and logic power 0v? I think it does. just triple checking as things get expensive if I get them wrong and I don't want to go down that track regards Andrew On Sat, May 30, 2020 at 2:14 PM andrew beck <andrewbeck0...@gmail.com> 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 > > > 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
