[Emc-users] Grounding

[Roland Jollivet]

Definitely do not tie 0VDC to ground. It will often cause problems with the
switching power supply.




On 13 July 2018 at 04:55, Dave Cole  wrote:

> Typically in a multi-panel control system setup there is a ground bar in
> each panel.   The incoming AC power ground is tied to this and the 24 volt
> power supply negative is tied to the local ground bar just as I described
> before.  If all of these panels are on a common machine frame, the ground
> bars are oftentimes linked together with a heavy bonding copper cable (like
> a 4 gauge or heavier bare cable).
>
> You don't want to rely on the machine frame to be the ground conductor.
> The systems I used to work on way back when were all AC, 120 volts for the
> controls and you could run control wire circuits for 1000 ft with only
> occasional problems.  Way back when, a controls electrician typically
> didn't carry a voltmeter with him.   He used a wiggy.
> https://en.wikipedia.org/wiki/Solenoid_voltmeter
>
> Now you just pull Ethernet cables between control panels.
> Not much 120 VAC control wiring is being installed any longer.
>
> Dave
>
>
>
>
> On 7/12/2018 6:33 PM, John Dammeyer wrote:
>
>> So what happens when the equipment with the 24V supply is 30m long in
>> multiple steel frames?  There would be a bonding wire from frame to frame
>> since you wouldn't want to bond one end to one AC ground outlet and the
>> other end to a different AC ground outlet.
>>
>> What if you have 30A, 24V supplies at each end of the machine or in each
>> module.If each 24V supply minus terminal is grounded to the frame and
>> you run a common ground bus through the machine you now have the frame and
>> the ground bus serving as the DC ground path.   You wouldn't want to run DC
>> ground on the frame.
>>
>> I worked on a machine once that had I think 42 modules.  Each one was
>> independent and inserted two advertisement flyers into newspapers.  A
>> client would buy the number of modules they thought they would need for the
>> number of insertions.   I don't think they ran 24V from the front end all
>> the way through so probably AC to each module and a 24V supply for the
>> motors and relays (and air valves).   The entire set of modules was also
>> connected via CAN bus so we have the CAN signal ground in that match too.
>> It was a long time ago and I was brought in to solve CAN bus problems so I
>> never really looked closely at the power.
>>
>> What about if you have a vehicle instead.  Might have equipment mounted
>> on frames  that need to be bonded together.  If they run an independent
>> battery pack and/or genset then the DC ground doesn't need to touch the
>> frame.  But what if the vehicle 12V battery which does have negative
>> connected to the frame also provides some sort of vehicle connection.  Say
>> a radio that has a modem that connects to a PC.
>>
>> Logic would dictate you want the DC ground of everything connected to the
>> frame with some bond wires even if just for lightning protection.  But now
>> you run risk of ground loops on the 12V circuits interfering with the
>> system battery pack.
>>
>> Do the hybrid electric cars connect the negative DC of the high voltage
>> battery pack to the frame?
>>
>> I'm amazed at the can of worms this question raises.  We haven't even
>> discussed the electrical noise issues coupled through the lowest impedance
>> path.
>>
>> John
>>
>>
>> -Original Message-
>>> From: Dave Cole [mailto:linuxcncro...@gmail.com]
>>> Sent: July-12-18 2:57 PM
>>> To: emc-users@lists.sourceforge.net
>>> Subject: Re: [Emc-users] Grounding
>>>
>>> I think you need to define what you mean by "grounding".
>>>
>>> If you have a 24 volt DC powered control system, like an industrial
>>> control panel, typically the 24 volt DC power supply/s will tie the 0V
>>> terminal on the power supply to frame/panel ground.�� These are the big
>>> 10, 20, 40 amp 24 volt DC power supplies that power the control panel
>>> components.
>>>
>>> There are some good reasons to do this.
>>> Many industrial control components have loose ties frame ground
>>> internally and if you don't tie 0V to frame ground they malfunction!
>>> Many of these components have specifications for the number of volts
>>> that the M, 0V terminal can be away from chassis ground.
>>>
>>> The grounding is normally done by a single green wire from the power
>>> supply 0V terminal to the ground bus bar.�� That way if there are
>>> grounding/common issues you can lift that wire to aid in debugging the
>>> system.
>>>
>>> When you get into 5V systems, breakout boards, etc, I tend to keep those
>>> isolated from frame/panel ground.��� I think there are only downsides to
>>> connecting the 0V terminal of a 5 volt power supply to frame ground.
>>>
>>> If you look at industrial drives, they always separate the frame/safety
>>> ground from the signal "ground" or "reference" terminal.�� They are
>>> usually two different terminals.� One is oftentimes a cable lug or
>>> bolt-cable 

Re: [Emc-users] Grounding

[Erik Christiansen]

On 12.07.18 15:33, John Dammeyer wrote:
> So what happens when the equipment with the 24V supply is 30m long in
> multiple steel frames?  There would be a bonding wire from frame to
> frame since you wouldn't want to bond one end to one AC ground outlet
> and the other end to a different AC ground outlet.

Rather than chain a whole lot of modules on one long ground wire, where
each can interfere with the others by imposing HF noise on the common
ground impedance, thereby coupling it into the others, I'd wire them
individually back to the power supply. ("Star Earth", as Gene so rightly
points out.)

If there is internal DC connection to the equipment case, I'd provide
isolated mounts to defeat the earth loops which would most likely
otherwise cause problems.

If there's RF EMI into the equipment from a hostile environment, then
I'd be tempted to connect the metallic case to its internal equipment's
earth via a good RF bypass capacitor, to put the circuitry's Faraday
cage at earth potential.

...

> What about if you have a vehicle instead.  Might have equipment
> mounted on frames  that need to be bonded together.  If they run an
> independent battery pack and/or genset then the DC ground doesn't need
> to touch the frame.  But what if the vehicle 12V battery which does
> have negative connected to the frame also provides some sort of
> vehicle connection.  Say a radio that has a modem that connects to a
> PC.  

One connection, as at the battery would be fine. It's earth loops which
best radiate EMI, proportional to the area of the loop antenna.

> Logic would dictate you want the DC ground of everything connected to
> the frame with some bond wires even if just for lightning protection.
> But now you run risk of ground loops on the 12V circuits interfering
> with the system battery pack.  

I'd put gaseous arrestors on external lines as primary protection,
followed by MOVs or transorbs further inboard, with some impedance
between, to further clamp the surge not entirely swallowed by the
arrestors. But I'd try to read up on that bit first. Grounded shielding
on external wiring has to help too.

Erik

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Re: [Emc-users] Grounding

[Dave Cole]

Typically in a multi-panel control system setup there is a ground bar in 
each panel.   The incoming AC power ground is tied to this and the 24 
volt power supply negative is tied to the local ground bar just as I 
described before.  If all of these panels are on a common machine frame, 
the ground bars are oftentimes linked together with a heavy bonding 
copper cable (like a 4 gauge or heavier bare cable).


You don't want to rely on the machine frame to be the ground 
conductor.    The systems I used to work on way back when were all AC, 
120 volts for the controls and you could run control wire circuits for 
1000 ft with only occasional problems.  Way back when, a controls 
electrician typically didn't carry a voltmeter with him.   He used a wiggy.

https://en.wikipedia.org/wiki/Solenoid_voltmeter

Now you just pull Ethernet cables between control panels.
Not much 120 VAC control wiring is being installed any longer.

Dave



On 7/12/2018 6:33 PM, John Dammeyer wrote:

So what happens when the equipment with the 24V supply is 30m long in multiple 
steel frames?  There would be a bonding wire from frame to frame since you 
wouldn't want to bond one end to one AC ground outlet and the other end to a 
different AC ground outlet.

What if you have 30A, 24V supplies at each end of the machine or in each 
module.If each 24V supply minus terminal is grounded to the frame and you 
run a common ground bus through the machine you now have the frame and the 
ground bus serving as the DC ground path.   You wouldn't want to run DC ground 
on the frame.

I worked on a machine once that had I think 42 modules.  Each one was 
independent and inserted two advertisement flyers into newspapers.  A client 
would buy the number of modules they thought they would need for the number of 
insertions.   I don't think they ran 24V from the front end all the way through 
so probably AC to each module and a 24V supply for the motors and relays (and 
air valves).   The entire set of modules was also connected via CAN bus so we 
have the CAN signal ground in that match too.  It was a long time ago and I was 
brought in to solve CAN bus problems so I never really looked closely at the 
power.

What about if you have a vehicle instead.  Might have equipment mounted on 
frames  that need to be bonded together.  If they run an independent battery 
pack and/or genset then the DC ground doesn't need to touch the frame.  But 
what if the vehicle 12V battery which does have negative connected to the frame 
also provides some sort of vehicle connection.  Say a radio that has a modem 
that connects to a PC.

Logic would dictate you want the DC ground of everything connected to the frame 
with some bond wires even if just for lightning protection.  But now you run 
risk of ground loops on the 12V circuits interfering with the system battery 
pack.

Do the hybrid electric cars connect the negative DC of the high voltage battery 
pack to the frame?

I'm amazed at the can of worms this question raises.  We haven't even discussed 
the electrical noise issues coupled through the lowest impedance path.

John



-Original Message-
From: Dave Cole [mailto:linuxcncro...@gmail.com]
Sent: July-12-18 2:57 PM
To: emc-users@lists.sourceforge.net
Subject: Re: [Emc-users] Grounding

I think you need to define what you mean by "grounding".

If you have a 24 volt DC powered control system, like an industrial
control panel, typically the 24 volt DC power supply/s will tie the 0V
terminal on the power supply to frame/panel ground.�� These are the big
10, 20, 40 amp 24 volt DC power supplies that power the control panel
components.

There are some good reasons to do this.
Many industrial control components have loose ties frame ground
internally and if you don't tie 0V to frame ground they malfunction!
Many of these components have specifications for the number of volts
that the M, 0V terminal can be away from chassis ground.

The grounding is normally done by a single green wire from the power
supply 0V terminal to the ground bus bar.�� That way if there are
grounding/common issues you can lift that wire to aid in debugging the
system.

When you get into 5V systems, breakout boards, etc, I tend to keep those
isolated from frame/panel ground.��� I think there are only downsides to
connecting the 0V terminal of a 5 volt power supply to frame ground.

If you look at industrial drives, they always separate the frame/safety
ground from the signal "ground" or "reference" terminal.�� They are
usually two different terminals.� One is oftentimes a cable lug or
bolt-cable lug connection, and the other a small screw terminal.

FWIW, I am in the machine controls business.� PCs are common
components
in machine controls.

Dave


On 7/12/2018 4:31 PM, John Dammeyer wrote:

Thanks,
I'm not concerned about the AC ground side of things.

Internet searches on this subject generally seem to agree that DC ground
doesn't and shouldn't be connected to the metal frame earth 

Re: [Emc-users] Grounding

[Gene Heskett]

On Thursday 12 July 2018 17:31:17 andy pugh wrote:

> On 12 July 2018 at 20:12, John Dammeyer  wrote:
> > Is it standard practice to connect the DC Servo and DC
> > Instrumentation Bus to the machine frame ground which is connected
> > to power line earth?  Or is it more normal practice to keep the DC
> > isolated from the 'earth' ground.
>
> I think it might be a good idea to keep the high voltage DC bus
> separated from Signal Ground. I don't know this for a fact and I am
> only mentioning it because the other replies seem to be glossing over
> that part of the question.

So I did Andy, but the connection there cannot be opened if you are using 
one of Jon's pwm-servo amps to drive the spindle, which I am. In that 
driver, ground, the negative end of a 126 volt multi-amp (around 20) 
supply, and the common of the pwm signal that controls it are one and 
the same terminal on that driver. I too would like to see some isolation 
there, but it does in fact work well if the rest of the grounding is 
solid. Twice, as thats essentially the same circuit in The Little 
Monster 7x12.

-- 
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)
Genes Web page 

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Re: [Emc-users] Grounding

[John Dammeyer]

So what happens when the equipment with the 24V supply is 30m long in multiple 
steel frames?  There would be a bonding wire from frame to frame since you 
wouldn't want to bond one end to one AC ground outlet and the other end to a 
different AC ground outlet.

What if you have 30A, 24V supplies at each end of the machine or in each 
module.If each 24V supply minus terminal is grounded to the frame and you 
run a common ground bus through the machine you now have the frame and the 
ground bus serving as the DC ground path.   You wouldn't want to run DC ground 
on the frame.  

I worked on a machine once that had I think 42 modules.  Each one was 
independent and inserted two advertisement flyers into newspapers.  A client 
would buy the number of modules they thought they would need for the number of 
insertions.   I don't think they ran 24V from the front end all the way through 
so probably AC to each module and a 24V supply for the motors and relays (and 
air valves).   The entire set of modules was also connected via CAN bus so we 
have the CAN signal ground in that match too.  It was a long time ago and I was 
brought in to solve CAN bus problems so I never really looked closely at the 
power.

What about if you have a vehicle instead.  Might have equipment mounted on 
frames  that need to be bonded together.  If they run an independent battery 
pack and/or genset then the DC ground doesn't need to touch the frame.  But 
what if the vehicle 12V battery which does have negative connected to the frame 
also provides some sort of vehicle connection.  Say a radio that has a modem 
that connects to a PC.  

Logic would dictate you want the DC ground of everything connected to the frame 
with some bond wires even if just for lightning protection.  But now you run 
risk of ground loops on the 12V circuits interfering with the system battery 
pack.  

Do the hybrid electric cars connect the negative DC of the high voltage battery 
pack to the frame?

I'm amazed at the can of worms this question raises.  We haven't even discussed 
the electrical noise issues coupled through the lowest impedance path.

John


> -Original Message-
> From: Dave Cole [mailto:linuxcncro...@gmail.com]
> Sent: July-12-18 2:57 PM
> To: emc-users@lists.sourceforge.net
> Subject: Re: [Emc-users] Grounding
> 
> I think you need to define what you mean by "grounding".
> 
> If you have a 24 volt DC powered control system, like an industrial
> control panel, typically the 24 volt DC power supply/s will tie the 0V
> terminal on the power supply to frame/panel ground.�� These are the big
> 10, 20, 40 amp 24 volt DC power supplies that power the control panel
> components.
> 
> There are some good reasons to do this.
> Many industrial control components have loose ties frame ground
> internally and if you don't tie 0V to frame ground they malfunction!
> Many of these components have specifications for the number of volts
> that the M, 0V terminal can be away from chassis ground.
> 
> The grounding is normally done by a single green wire from the power
> supply 0V terminal to the ground bus bar.�� That way if there are
> grounding/common issues you can lift that wire to aid in debugging the
> system.
> 
> When you get into 5V systems, breakout boards, etc, I tend to keep those
> isolated from frame/panel ground.��� I think there are only downsides to
> connecting the 0V terminal of a 5 volt power supply to frame ground.
> 
> If you look at industrial drives, they always separate the frame/safety
> ground from the signal "ground" or "reference" terminal.�� They are
> usually two different terminals.� One is oftentimes a cable lug or
> bolt-cable lug connection, and the other a small screw terminal.
> 
> FWIW, I am in the machine controls business.� PCs are common
> components
> in machine controls.
> 
> Dave
> 
> 
> On 7/12/2018 4:31 PM, John Dammeyer wrote:
> > Thanks,
> > I'm not concerned about the AC ground side of things.
> >
> > Internet searches on this subject generally seem to agree that DC ground
> > doesn't and shouldn't be connected to the metal frame earth ground at
> any
> > point.  If it is either through a capacitor  or a 100 ohm resistor.
> >
> > I remember many years ago working on Trim & Form Equipment in The
> > Netherlands we ran into problems with the PCs used for the User interface
> > (Pentium 386) had the power supply internally connect the DC ground to
> the
> > frame.  Caused all sorts of havoc.  I don't remember what the solution was.
> >
> > Jeff Birt also suggests not connecting DC ground to the frame on one
> group's
> > posting.   Obviously there may be Break Out Boards that break this rule but
> > then they may also be made by hobbiests who have gone into the
> machine
> > controls business and don't really know.
> >
> > John
> >
> >> -Original Message-
> >> From: Gene Heskett [mailto:ghesk...@shentel.net]
> >> Sent: July-12-18 1:16 PM
> >> To: emc-users@lists.sourceforge.net
> >> Subject: 

Re: [Emc-users] Grounding

[Dave Cole]

Agreed, I have never seen a high voltage DC drive bus leg connected to 
ground.  That could cause all kinds of problems!


Dave

On 7/12/2018 5:31 PM, andy pugh wrote:

On 12 July 2018 at 20:12, John Dammeyer  wrote:

Is it standard practice to connect the DC Servo and DC Instrumentation Bus
to the machine frame ground which is connected to power line earth?  Or is
it more normal practice to keep the DC isolated from the 'earth' ground.

I think it might be a good idea to keep the high voltage DC bus
separated from Signal Ground. I don't know this for a fact and I am
only mentioning it because the other replies seem to be glossing over
that part of the question.



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Re: [Emc-users] Grounding

[Dave Cole]

I think you need to define what you mean by "grounding".

If you have a 24 volt DC powered control system, like an industrial 
control panel, typically the 24 volt DC power supply/s will tie the 0V 
terminal on the power supply to frame/panel ground.   These are the big 
10, 20, 40 amp 24 volt DC power supplies that power the control panel 
components.


There are some good reasons to do this.
Many industrial control components have loose ties frame ground 
internally and if you don't tie 0V to frame ground they malfunction!
Many of these components have specifications for the number of volts 
that the M, 0V terminal can be away from chassis ground.


The grounding is normally done by a single green wire from the power 
supply 0V terminal to the ground bus bar.   That way if there are 
grounding/common issues you can lift that wire to aid in debugging the 
system.


When you get into 5V systems, breakout boards, etc, I tend to keep those 
isolated from frame/panel ground.    I think there are only downsides to 
connecting the 0V terminal of a 5 volt power supply to frame ground.


If you look at industrial drives, they always separate the frame/safety 
ground from the signal "ground" or "reference" terminal.   They are 
usually two different terminals.  One is oftentimes a cable lug or 
bolt-cable lug connection, and the other a small screw terminal.


FWIW, I am in the machine controls business.  PCs are common components 
in machine controls.


Dave


On 7/12/2018 4:31 PM, John Dammeyer wrote:

Thanks,
I'm not concerned about the AC ground side of things.

Internet searches on this subject generally seem to agree that DC ground
doesn't and shouldn't be connected to the metal frame earth ground at any
point.  If it is either through a capacitor  or a 100 ohm resistor.

I remember many years ago working on Trim & Form Equipment in The
Netherlands we ran into problems with the PCs used for the User interface
(Pentium 386) had the power supply internally connect the DC ground to the
frame.  Caused all sorts of havoc.  I don't remember what the solution was.

Jeff Birt also suggests not connecting DC ground to the frame on one group's
posting.   Obviously there may be Break Out Boards that break this rule but
then they may also be made by hobbiests who have gone into the machine
controls business and don't really know.

John


-Original Message-
From: Gene Heskett [mailto:ghesk...@shentel.net]
Sent: July-12-18 1:16 PM
To: emc-users@lists.sourceforge.net
Subject: Re: [Emc-users] Grounding

On Thursday 12 July 2018 15:12:40 John Dammeyer wrote:


Is it standard practice to connect the DC Servo and DC Instrumentation
Bus to the machine frame ground which is connected to power line
earth?  Or is it more normal practice to keep the DC isolated from the
'earth' ground.

John

Generally speaking its a good idea to have then all come together at a
common  bolt, also called a star ground.  The bolt is the star center
point and all other ground circuits radiate from it..  The machines
frame ground should connect to this common point, and it should be
ohm-meter verified that there is not another connection between that
bolt and the machine frame if the frame grounding wire is disconnected.

This means that its good practice to have shielded motor and sensor
cables, but the shield is cut short, not connected at the frame end of
the run.  If there is another connection, then you have a ground loop
which can inject several tens of volts of noise back into the interface
card, potentially damaging it. Or worse, inject noise into a stepper
drive resulting in a gradual drift of the homed point which=wrecked, out
of spec parts.

IOW, the motor power supplies should be the only circuit that connects to
the 3rd pin of the power cord, and that 3rd pin should be connected only
to that common bolt. Do not connect this 3rd wire to the supplies, but
to this bolt, and take a separate wire from the bolt back to the ground
symbol on the PSU's. And if that ground has continuity to the shell of
the PSU, mount it insulated to open that ground loop. A piece of pcb
material, glued to the chassis, and the PSU's glued to the pcb should do
it nicely.

IHTH.

--
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)
Genes Web page 




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Re: [Emc-users] Grounding

[andy pugh]

On 12 July 2018 at 20:12, John Dammeyer  wrote:
> Is it standard practice to connect the DC Servo and DC Instrumentation Bus
> to the machine frame ground which is connected to power line earth?  Or is
> it more normal practice to keep the DC isolated from the 'earth' ground.

I think it might be a good idea to keep the high voltage DC bus
separated from Signal Ground. I don't know this for a fact and I am
only mentioning it because the other replies seem to be glossing over
that part of the question.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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Re: [Emc-users] Grounding

[John Dammeyer]

HI Dave,
The problem comes in when some devices ground the DC to the frame internally.  
I don't see an issue with grounding the DC bus bar to earth ground at one 
point.  
I'm just looking at "standard practices" which all suggest no connection or at 
only one spot.
Thanks
John


> -Original Message-
> From: Dave Cole [mailto:linuxcncro...@gmail.com]
> Sent: July-12-18 1:26 PM
> To: emc-users@lists.sourceforge.net
> Subject: Re: [Emc-users] Grounding
> 
> Normally, a single ground point is established in the cabinet and all of
> the grounds tie to that one point.
> 
> The same point is also tied power line ground.
> 
> The multi hole bus bars they sell for use in a AC power breaker boxes
> work well for this.
> Every big box home store will have a selection of them.
> 
> I screw that to the panel back plane and run all of the ground wires to
> that block.� That grounds the steel panel, backplane, and everything in it.
> The incoming power ground wire is also connected to the same bus bar.
> 
> Dave
> 
> On 7/12/2018 3:12 PM, John Dammeyer wrote:
> > Is it standard practice to connect the DC Servo and DC Instrumentation Bus
> > to the machine frame ground which is connected to power line earth?  Or
> is
> > it more normal practice to keep the DC isolated from the 'earth' ground.
> >
> > John
> >
> >
> >
> > --
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[Emc-users] Parallel Port Docs revisited

[Joe Hildreth]

I think I done a poor job of explaining my question, although I believe Andy 
Pugh got it. I created a video demonstrating what I mean, although not the 
great. Was wondering if someone would correct my mis-information or confirm 
what I think to be true. If I am correct, can we get it changed in the 
documentation. 

Here is the video 

https://www.youtube.com/watch?v=QE6tW6W_5Po 

I am sorry if I am being a pain in the a$$ 

Regards, 

Joe 

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Re: [Emc-users] Grounding

[John Dammeyer]

Thanks,
I'm not concerned about the AC ground side of things.  

Internet searches on this subject generally seem to agree that DC ground
doesn't and shouldn't be connected to the metal frame earth ground at any
point.  If it is either through a capacitor  or a 100 ohm resistor.

I remember many years ago working on Trim & Form Equipment in The
Netherlands we ran into problems with the PCs used for the User interface
(Pentium 386) had the power supply internally connect the DC ground to the
frame.  Caused all sorts of havoc.  I don't remember what the solution was.

Jeff Birt also suggests not connecting DC ground to the frame on one group's
posting.   Obviously there may be Break Out Boards that break this rule but
then they may also be made by hobbiests who have gone into the machine
controls business and don't really know.

John

> -Original Message-
> From: Gene Heskett [mailto:ghesk...@shentel.net]
> Sent: July-12-18 1:16 PM
> To: emc-users@lists.sourceforge.net
> Subject: Re: [Emc-users] Grounding
> 
> On Thursday 12 July 2018 15:12:40 John Dammeyer wrote:
> 
> > Is it standard practice to connect the DC Servo and DC Instrumentation
> > Bus to the machine frame ground which is connected to power line
> > earth?  Or is it more normal practice to keep the DC isolated from the
> > 'earth' ground.
> >
> > John
> 
> Generally speaking its a good idea to have then all come together at a
> common  bolt, also called a star ground.  The bolt is the star center
> point and all other ground circuits radiate from it..  The machines
> frame ground should connect to this common point, and it should be
> ohm-meter verified that there is not another connection between that
> bolt and the machine frame if the frame grounding wire is disconnected.
> 
> This means that its good practice to have shielded motor and sensor
> cables, but the shield is cut short, not connected at the frame end of
> the run.  If there is another connection, then you have a ground loop
> which can inject several tens of volts of noise back into the interface
> card, potentially damaging it. Or worse, inject noise into a stepper
> drive resulting in a gradual drift of the homed point which=wrecked, out
> of spec parts.
> 
> IOW, the motor power supplies should be the only circuit that connects to
> the 3rd pin of the power cord, and that 3rd pin should be connected only
> to that common bolt. Do not connect this 3rd wire to the supplies, but
> to this bolt, and take a separate wire from the bolt back to the ground
> symbol on the PSU's. And if that ground has continuity to the shell of
> the PSU, mount it insulated to open that ground loop. A piece of pcb
> material, glued to the chassis, and the PSU's glued to the pcb should do
> it nicely.
> 
> IHTH.
> 
> --
> 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)
> Genes Web page 
> 
>

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Re: [Emc-users] So, how's Ethernet?

[Sven Wesley]

These little babies. I have a few of them already and my kids have the i7
version and they are fast. Linux just runs, no trouble. One Ethernet and
Wifi in the same box. Perfect.
https://www.dustin.se/product/5011010658/nuc-kaby-lake-wifi



On Wed, Jul 11, 2018 at 3:32 PM Eric Keller  wrote:

> Which Intel NUC did you get?  A couple of years ago I got a zotac box with
> dual ethernet ports thinking that I might use it as either a router or to
> drive an ethernet mesa board.  I think it will end up as a router.
> Eric Keller
> Boalsburg, Pennsylvania
>
> On Wed, Jul 11, 2018 at 4:05 AM Sven Wesley  wrote:
>
> > Yes, looks like your email with the link went to me and not to the list.
> > Anyway, the Mesa card looks promising. Intel NUC and Mesa boards on the
> > way!
> >
> > /S
> >
> > On Tue, Jul 10, 2018 at 5:14 PM Les Newell 
> > wrote:
> >
> > > I beat you to it with the same link but it looks like my email went
> > > directly to Sven, rather than to the list. For some reason when I reply
> > > to this list the replies usually end up going direct to the sender
> > > rather than to the list.
> > >
> > > Les
> > >
> > > On 10/07/2018 13:38, andy pugh wrote:
> > > > On 10 July 2018 at 11:47, Sven Wesley  wrote:
> > > >> You too late, Andy. ;)
> > > > Too late in the sense that you have already bought the UC400 ?
> > > >
> > >
> > >
> > >
> > >
> >
> --
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> > > engaging tech sites, Slashdot.org! http://sdm.link/slashdot
> > > ___
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> > > Emc-users@lists.sourceforge.net
> > > https://lists.sourceforge.net/lists/listinfo/emc-users
> > >
> >
> >
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> > https://lists.sourceforge.net/lists/listinfo/emc-users
> >
>
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Re: [Emc-users] Grounding

[Dave Cole]

Normally, a single ground point is established in the cabinet and all of 
the grounds tie to that one point.


The same point is also tied power line ground.

The multi hole bus bars they sell for use in a AC power breaker boxes 
work well for this.

Every big box home store will have a selection of them.

I screw that to the panel back plane and run all of the ground wires to 
that block.  That grounds the steel panel, backplane, and everything in it.

The incoming power ground wire is also connected to the same bus bar.

Dave

On 7/12/2018 3:12 PM, John Dammeyer wrote:

Is it standard practice to connect the DC Servo and DC Instrumentation Bus
to the machine frame ground which is connected to power line earth?  Or is
it more normal practice to keep the DC isolated from the 'earth' ground.
  
John
  
  
  
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Re: [Emc-users] Grounding

[Gene Heskett]

On Thursday 12 July 2018 15:12:40 John Dammeyer wrote:

> Is it standard practice to connect the DC Servo and DC Instrumentation
> Bus to the machine frame ground which is connected to power line
> earth?  Or is it more normal practice to keep the DC isolated from the
> 'earth' ground.
>
> John

Generally speaking its a good idea to have then all come together at a 
common  bolt, also called a star ground.  The bolt is the star center 
point and all other ground circuits radiate from it..  The machines 
frame ground should connect to this common point, and it should be 
ohm-meter verified that there is not another connection between that 
bolt and the machine frame if the frame grounding wire is disconnected.

This means that its good practice to have shielded motor and sensor 
cables, but the shield is cut short, not connected at the frame end of 
the run.  If there is another connection, then you have a ground loop 
which can inject several tens of volts of noise back into the interface 
card, potentially damaging it. Or worse, inject noise into a stepper 
drive resulting in a gradual drift of the homed point which=wrecked, out 
of spec parts.

IOW, the motor power supplies should be the only circuit that connects to 
the 3rd pin of the power cord, and that 3rd pin should be connected only 
to that common bolt. Do not connect this 3rd wire to the supplies, but 
to this bolt, and take a separate wire from the bolt back to the ground 
symbol on the PSU's. And if that ground has continuity to the shell of 
the PSU, mount it insulated to open that ground loop. A piece of pcb 
material, glued to the chassis, and the PSU's glued to the pcb should do 
it nicely.

IHTH.

-- 
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)
Genes Web page 

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[Emc-users] Grounding

[John Dammeyer]

Is it standard practice to connect the DC Servo and DC Instrumentation Bus
to the machine frame ground which is connected to power line earth?  Or is
it more normal practice to keep the DC isolated from the 'earth' ground.
 
John
 
 
 
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Re: [Emc-users] 7i92 bitfile programming problem

[Peter C. Wallace]

On Thu, 12 Jul 2018, Les Newell wrote:


Date: Thu, 12 Jul 2018 16:21:42 +0100
From: Les Newell 
Reply-To: "Enhanced Machine Controller (EMC)"

To: emc-users@lists.sourceforge.net
Subject: [Emc-users] 7i92 bitfile programming problem

I am trying to program a 7i92 using Mesaflash and I am having a problem:

mesaflash --device 7i92 --write 7i92_G540x2D.bit

Error: wrong bitfile destination device: 6slx9tqg144, should be xc6slx9

Looking at the board it does appear to have an xc6slx9. Has the 7i92 been 
redesigned recently? If so, where can I find suitable bitfiles? A few months 
back I used a 7i92 on another job and didn't have this problem.


Les



I think that means you have a old version of mesaflash




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Peter Wallace
Mesa Electronics

(\__/)
(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination.


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[Emc-users] 7i92 bitfile programming problem

[Les Newell]

I am trying to program a 7i92 using Mesaflash and I am having a problem:

mesaflash --device 7i92 --write 7i92_G540x2D.bit

Error: wrong bitfile destination device: 6slx9tqg144, should be xc6slx9

Looking at the board it does appear to have an xc6slx9. Has the 7i92 
been redesigned recently? If so, where can I find suitable bitfiles? A 
few months back I used a 7i92 on another job and didn't have this problem.


Les



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